Ultrasonic Vibration Assisted Grinding of Bio-ceramic Materials: Modeling, Simulation, and Experimental Investigations on Edge Chipping

Science.gov (United States)

Tesfay, Hayelom D.

Bio-ceramics are those engineered materials that find their applications in the field of biomedical engineering or medicine. They have been widely used in dental restorations, repairing bones, joint replacements, pacemakers, kidney dialysis machines, and respirators. etc. due to their physico-chemical properties, such as excellent corrosion resistance, good biocompatibility, high strength and high wear resistance. Because of their inherent brittleness and hardness nature they are difficult to machine to exact sizes and dimensions. Abrasive machining processes such as grinding is one of the most widely used manufacturing processes for bioceramics. However, the principal technical challenge resulted from these machining is edge chipping. Edge chipping is a common edge failure commonly observed during the machining of bio-ceramic materials. The presence of edge chipping on bio-ceramic products affects dimensional accuracy, increases manufacturing cost, hider their industrial applications and causes potential failure during service. To overcome these technological challenges, a new ultrasonic vibration-assisted grinding (UVAG) manufacturing method has been developed and employed in this research. The ultimate aim of this study is to develop a new cost-effective manufacturing process relevant to eliminate edge chippings in grinding of bio-ceramic materials. In this dissertation, comprehensive investigations will be carried out using experimental, theoretical, and numerical approaches to evaluate the effect of ultrasonic vibrations on edge chipping of bioceramics. Moreover, effects of nine input variables (static load, vibration frequency, grinding depth, spindle speed, grinding distance, tool speed, grain size, grain number, and vibration amplitude) on edge chipping will be studied based on the developed models. Following a description of previous research and existing approaches, a series of experimental tests on three bio-ceramic materials (Lava, partially fired Lava

Ceramic-bonded abrasive grinding tools

Science.gov (United States)

Holcombe, Jr., Cressie E.; Gorin, Andrew H.; Seals, Roland D.

1994-01-01

Abrasive grains such as boron carbide, silicon carbide, alumina, diamond, cubic boron nitride, and mullite are combined with a cement primarily comprised of zinc oxide and a reactive liquid setting agent and solidified into abrasive grinding tools. Such grinding tools are particularly suitable for grinding and polishing stone, such as marble and granite.

Ceramic-bonded abrasive grinding tools

Science.gov (United States)

Holcombe, C.E. Jr.; Gorin, A.H.; Seals, R.D.

1994-11-22

Abrasive grains such as boron carbide, silicon carbide, alumina, diamond, cubic boron nitride, and mullite are combined with a cement primarily comprised of zinc oxide and a reactive liquid setting agent and solidified into abrasive grinding tools. Such grinding tools are particularly suitable for grinding and polishing stone, such as marble and granite.

Grinding Parameter Optimization of Ultrasound-Aided Electrolytic in Process Dressing for Finishing Nanocomposite Ceramics

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Fan Chen

2016-01-01

Full Text Available In order to achieve the precision and efficient processing of nanocomposite ceramics, the ultrasound-aided electrolytic in process dressing method was proposed. But how to realize grinding parameter optimization, that is, the maximum processing efficiency, on the premise of the assurance of best workpiece quality is a problem that needs to be solved urgently. Firstly, this research investigated the influence of grinding parameters on material removal rate and critical ductile depth, and their mathematic models based on the existing models were developed to simulate the material removal process. Then, on the basis of parameter sensitivity analysis based on partial derivative, the sensitivity models of material removal rates on grinding parameter were established and computed quantitatively by MATLAB, and the key grinding parameter for optimal grinding process was found. Finally, the theoretical analyses were verified by experiments: the material removal rate increases with the increase of grinding parameters, including grinding depth (ap, axial feeding speed (fa, workpiece speed (Vw, and wheel speed (Vs; the parameter sensitivity of material removal rate was in a descending order as ap>fa>Vw>Vs; the most sensitive parameter (ap was optimized and it was found that the better machining result has been obtained when ap was about 3.73 μm.

Modification of surface texture by grinding and polishing lead zirconate titanate ceramics

International Nuclear Information System (INIS)

Cheng, S.; Lloyd, I.K.

1992-01-01

This paper reports that grinding and polishing affected the orientation of 90 degrees domains at the surface of lead zirconate titanate (PZT) ceramics. This was quantified by using changes in the intensity ratio of the (002) and (200) X-ray reflections. Grinding unpoled PZT with 600-grit SiC paper gave X-ray intensity ratios similar to those of poled material. This implies that 90 degrees domain realignments had occurred in the near surface region probed by the X-rays. Grinding poled samples with 600-grit SiC further increased the X-ray intensity ratio beyond that caused by poling, indicating that additional surface reorientation of 90 degrees domains had occurred. The effects of diamond polishing depended on the size of the diamond particles. The use of 6-μm diamond had no effect on the (002)/(200) intensity ratio of either poled or unpoled samples, while polishing with 15- or 45-μm diamond significantly enhanced the 90 degrees domain rotation. In unpoled samples, the increase in the X-ray intensity ratio then approached that induced by poling or grinding with 600-grit SiC paper. While the observed increase in X-ray intensity ratio upon grinding is attributed to the rotation of 90 degrees domains, the simultaneous formation of 180 degrees domains appears to minimize or reduce the increase in electrical polarization

Mechanical behavior of a Y-TZP ceramic for monolithic restorations: effect of grinding and low-temperature aging.

Science.gov (United States)

Pereira, G K R; Silvestri, T; Camargo, R; Rippe, M P; Amaral, M; Kleverlaan, C J; Valandro, L F

2016-06-01

This study aimed to investigate the effects of grinding with diamond burs and low-temperature aging on the mechanical behavior (biaxial flexural strength and structural reliability), surface topography, and phase transformation of a Y-TZP ceramic for monolithic dental restorations. Disc-shaped specimens (Zirlux FC, Ivoclar Vivadent) were manufactured according to ISO 6872 (2008) and divided in accordance with two factors: "grinding - 3 levels" and "LTD - 2 levels". Grinding was performed using a contra-angle handpiece under constant water-cooling with different grit-sizes (extra-fine and coarse diamond burs). LTD was simulated in an autoclave at 134°C, under a pressure of 2 bar, over a period of 20h. Surface topography analysis showed an increase in roughness based on surface treatment grit-size (Coarse>Xfine>Ctrl), LTD did not influence roughness values. Both grinding and LTD promoted an increase in the amount of m-phase, although different susceptibilities to degradation were observed. According to existing literature the increase of m-phase content is a direct indicative of Y-TZP degradation. Weibull analysis showed an increase in characteristic strength after grinding (Coarse=Xfine>Ctrl), while for LTD, distinct effects were observed (Ctrlgrinding showed not to be detrimental to the mechanical properties of Zirlux FC Y-TZP ceramic. Copyright © 2016 Elsevier B.V. All rights reserved.

The Influence of Tool Composite's Structure During Process of Diamond Grinding of Ceramic Materials

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Gawlik Józef

2014-12-01

Full Text Available This paper presents the results of the tests performed during the grinding process of the ceramic materials: – polycrystalline ceramics (Zirconium ZrO2 and mono-crystalline ceramics (sapphire α-Al2O3 by the diamond tools. Studies have shown that the concentration (thickening of the tool composite changes the tool's pore structure when using suitable wetted adamantine additives. Such modified composite has positive impact on tribological properties of the subsurface layer of the machined components. This is manifested by the reduction of the surface roughness and reduction of the vibration amplitude of the coefficient of friction. The possibilities of the positive effects when using wetted additives on the tool's composite during the pressing (briquetting stage confirm the study results.

Grinding damage assessment for CAD-CAM restorative materials.

Science.gov (United States)

Curran, Philippe; Cattani-Lorente, Maria; Anselm Wiskott, H W; Durual, Stéphane; Scherrer, Susanne S

2017-03-01

To assess surface/subsurface damage after grinding with diamond discs on five CAD-CAM restorative materials and to estimate potential losses in strength based on crack size measurements of the generated damage. The materials tested were: Lithium disilicate (LIT) glass-ceramic (e.max CAD), leucite glass-ceramic (LEU) (Empress CAD), feldspar ceramic (VM2) (Vita Mark II), feldspar ceramic-resin infiltrated (EN) (Enamic) and a composite reinforced with nano ceramics (LU) (Lava Ultimate). Specimens were cut from CAD-CAM blocs and pair-wise mirror polished for the bonded interface technique. Top surfaces were ground with diamond discs of respectively 75, 54 and 18μm. Chip damage was measured on the bonded interface using SEM. Fracture mechanics relationships were used to estimate fracture stresses based on average and maximum chip depths assuming these to represent strength limiting flaws subjected to tension and to calculate potential losses in strength compared to manufacturer's data. Grinding with a 75μm diamond disc induced on a bonded interface critical chips averaging 100μm with a potential strength loss estimated between 33% and 54% for all three glass-ceramics (LIT, LEU, VM2). The softer materials EN and LU were little damage susceptible with chips averaging respectively 26μm and 17μm with no loss in strength. Grinding with 18μm diamond discs was still quite detrimental for LIT with average chip sizes of 43μm and a potential strength loss of 42%. It is essential to understand that when grinding glass-ceramics or feldspar ceramics with diamond discs surface and subsurface damage are induced which have the potential of lowering the strength of the ceramic. Careful polishing steps should be carried out after grinding especially when dealing with glass-ceramics. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Effect of grinding and aging on subcritical crack growth of a Y-TZP ceramic.

Science.gov (United States)

Amaral, Marina; Weitzel, Isabela Sandim Souza Leite; Silvestri, Tais; Guilardi, Luis Felipe; Pereira, Gabriel Kalil Rocha; Valandro, Luiz Felipe

2018-01-01

This study aimed to investigate slow crack growth (SCG) behavior of a zirconia ceramic after grinding and simulated aging with low-temperature degradation (LTD). Complementary analysis of hardness, surface topography, crystalline phase transformation, and roughness were also measured. Disc-shaped specimens (15 mm Ø × 1.2 mm thick, n = 42) of a full-contour Y-TZP ceramic (Zirlux FC, Amherst) were manufactured according to ISO:6872-2008, and then divided into: Ctrl - as-sintered condition; Ctrl LTD - as-sintered after aging in autoclave (134°C, 2 bar, 20 h); G - ground with coarse diamond bur (grit size 181 μm); G LTD - ground and aged. The SCG parameters were measured by a dynamic biaxial flexural test, which determines the tensile stress versus stress rate under four different rates: 100, 10, 1 and 0.1 MPa/s. LTD led to m-phase content increase, as well as grinding (m-phase content: Ctrl - 0%; G - 12.3%; G LTD - 59.9%; Ctrl LTD - 81%). Surface topography and roughness analyses showed that grinding created an irregular surface (increased roughness) and aging did not promote any relevant surface change. There was no statistical difference on surface hardness among different conditions. The control group presented the lowest strength values in all tested rates. Regarding SCG, ground conditions were less susceptible to SCG, delaying its occurrence. Aging (LTD) caused an increase in SCG susceptibility for the as-sintered condition (i.e. G < G LTD < Ctrl < Ctrl LTD).

Effect of Ceramic Surface Treatments After Machine Grinding on the Biaxial Flexural Strength of Different CAD/CAM Dental Ceramics.

Science.gov (United States)

Bagheri, Hossein; Hooshmand, Tabassom; Aghajani, Farzaneh

2015-09-01

This study aimed to evaluate the effect of different ceramic surface treatments after machining grinding on the biaxial flexural strength (BFS) of machinable dental ceramics with different crystalline phases. Disk-shape specimens (10mm in diameter and 1.3mm in thickness) of machinable ceramic cores (two silica-based and one zirconia-based ceramics) were prepared. Each type of the ceramic surfaces was then randomly treated (n=15) with different treatments as follows: 1) machined finish as control, 2) machined finish and sandblasting with alumina, and 3) machined finish and hydrofluoric acid etching for the leucite and lithium disilicate-based ceramics, and for the zirconia; 1) machined finish and post-sintered as control, 2) machined finish, post-sintered, and sandblasting, and 3) machined finish, post-sintered, and Nd;YAG laser irradiation. The BFS were measured in a universal testing machine. Data based were analyzed by ANOVA and Tukey's multiple comparisons post-hoc test (α=0.05). The mean BFS of machined finish only surfaces for leucite ceramic was significantly higher than that of sandblasted (P=0.001) and acid etched surfaces (P=0.005). A significantly lower BFS was found after sandblasting for lithium disilicate compared with that of other groups (Pceramics was affected by the type of ceramic material and surface treatment method. Sandblasting with alumina was detrimental to the strength of only silica-based ceramics. Nd:YAG laser irradiation may lead to substantial strength degradation of zirconia.

Mechanical behavior of a Y-TZP ceramic for monolithic restorations: effect of grinding and low-temperature aging

NARCIS (Netherlands)

Pereira, G.K.R.; Silvestri, T.; Camargo, R.; Rippe, M.P.; Amaral, M.; Kleverlaan, C.J.; Valandro, L.F.

2016-01-01

This study aimed to investigate the effects of grinding with diamond burs and low-temperature aging on the mechanical behavior (biaxial flexural strength and structural reliability), surface topography, and phase transformation of a Y-TZP ceramic for monolithic dental restorations. Disc-shaped

The effect of grinding on the mechanical behavior of Y-TZP ceramics: A systematic review and meta-analyses.

Science.gov (United States)

Pereira, G K R; Fraga, S; Montagner, A F; Soares, F Z M; Kleverlaan, C J; Valandro, L F

2016-10-01

The aim of this study was to systematically review the literature to assess the effect of grinding on the mechanical properties, structural stability and superficial characteristics of Y-TZP ceramics. The MEDLINE via PubMed and Web of Science (ISI - Web of Knowledge) electronic databases were searched with included peer-reviewed publications in English language and with no publication year limit. From 342 potentially eligible studies, 73 were selected for full-text analysis, 30 were included in the systematic review with 20 considered in the meta-analysis. Two reviewers independently selected the studies, extracted the data, and assessed the risk of bias. Statistical analyses were performed using RevMan 5.1, with random effects model, at a significance level of 0.05. A descriptive analysis considering phase transformation, Y-TZP grain size, Vickers hardness, residual stress and aging of all included studies were executed. Four outcomes were considered in the meta-analyses (factor: grinding x as-sintered) in global and subgroups analyses (grinding tool, grit-size and cooling) for flexural strength and roughness (Ra) data. A significant difference (pgrinding; subgroup analyses revealed that different parameters also lead to different effects on roughness. High heterogeneity was found in some comparisons. Generally grinding promotes decrease in strength and increase in roughness of Y-TZP ceramics. However, the use of a grinding tool that allows greater accuracy of the movement (i.e. contra angle hand-pieces coupled to slowspeed turbines), small grit size (<50μm) and the use of plenty coolant seem to be the main factors to decrease the defect introduction and allow the occurrence of the toughening transformation mechanism, decreasing the risk of deleterious impact on Y-TZP mechanical properties. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of different grinding burs on the physical properties of zirconia.

Science.gov (United States)

Lee, Kyung-Rok; Choe, Han-Cheol; Heo, Yu-Ri; Lee, Jang-Jae; Son, Mee-Kyoung

2016-04-01

Grinding with less stress on 3Y-TZP through proper selection of methods and instruments can lead to a long-term success of prosthesis. The purpose of this study was to compare the phase transformation and physical properties after zirconia surface grinding with 3 different grinding burs. Forty disc-shaped zirconia specimens were fabricated. Each Ten specimens were ground with AllCeramic SuperMax (NTI, Kahla, Germany), Dura-Green DIA (Shofu Inc., Kyoto, Japan), and Dura-Green (Shofu Inc., Kyoto, Japan). Ten specimens were not ground and used as a control group. After the specimen grinding, XRD analysis, surface roughness test, FE-SEM imaging, and biaxial flexural strength test were performed. After surface grinding, small amount of monoclinic phase in all experimental groups was observed. The phase change was higher in specimens, which were ground with Dura-Green DIA and AllCeramic SuperMax burs. The roughness of surfaces increased in specimens, which were ground with Dura-Green DIA and AllCeramic SuperMax burs than control groups and ground with Dura-Green. All experimental groups showed lower flexural strength than control group, but there was no statistically significant difference between control group and ground with Dura-Green DIA and AllCeramic SuperMax burs. The specimens, which were ground with Dura- Green showed the lowest strength. The use of dedicated zirconia-specific grinding burs such as Dura-Green DIA and AllCeramic SuperMax burs decreases the grinding time and did not significantly affect the flexural strength of zirconia, and therefore, they may be recommended. However, a fine polishing process should be accompanied to reduce the surface roughness after grinding.

The effect of grinding on the mechanical behavior of Y-TZP ceramics: A systematic review and meta-analyses

NARCIS (Netherlands)

Pereira, G.K.R.; Fraga, S.; Montagner, A.F.; Soares, F.Z.M.; Kleverlaan, C.J.; Valandro, L.F.

2016-01-01

The aim of this study was to systematically review the literature to assess the effect of grinding on the mechanical properties, structural stability and superficial characteristics of Y-TZP ceramics. The MEDLINE via PubMed and Web of Science (ISI – Web of Knowledge) electronic databases were

Effects of grinding on properties of Mg-PSZ ceramics prepared by the surface enrichment of zirconia powders

International Nuclear Information System (INIS)

Deb, S.; Das, S.R.

1995-01-01

Commercial grade zirconia powders of mean particle size of 3.21 microns were super-ground in wet condition in alcoholic medium in a Planetary Ball-Mill for 12-hours using a zirconia pot as well as balls, in order to avoid contaminations from the grinding media. Sedigraph analysis data show the mean particle sizes within the range of 0.4 to 0.2 micron. The super-ground zirconia powders were then treated with appropriate acid and alkali solutions in order to enrich the surfaces of zirconia powders. The chemical analysis reports depict the enrichment phenomena of the processed zirconia powders. Magnesium oxide of different mole percentages (3 to 9%) have been incorporated to the above super-ground and enriched zirconia powder and green specimens were prepared by pressing with a suitable pressure of 200 MPa to yield the green compaction density of 3.06 gm/cm 3 . The compacted green specimens were sintered without pressure at 1,480 C in air followed by normal cooling. X-ray diffraction patterns of the above sintered and cooled specimens have confirmed the formation of Mg-PSZ ceramics with 40% tetragonal phase. The sintered PSZ-products have shown very good surface properties but at the cost of transverse rupture strength. The effects of grinding were observed on the above Mg-PSZ ceramics which exhibit very little change in the tetragonal phase even after 30-minutes of grinding with a 60-mesh diamond wheel at a normal pressure of 4 kg/cm 2

Effect of machining parameters on surface integrity of silicon carbide ceramic using end electric discharge milling and mechanical grinding hybrid machining

International Nuclear Information System (INIS)

Ji, Renjie; Liu, Yonghong; Zhang, Yanzhen; Cai, Baoping; Li, Xiaopeng; Zheng, Chao

2013-01-01

A novel hybrid process that integrates end electric discharge (ED) milling and mechanical grinding is proposed. The process is able to effectively machine a large surface area on SiC ceramic with good surface quality and fine working environmental practice. The polarity, pulse on-time, and peak current are varied to explore their effects on the surface integrity, such as surface morphology, surface roughness, micro-cracks, and composition on the machined surface. The results show that positive tool polarity, short pulse on-time, and low peak current cause a fine surface finish. During the hybrid machining of SiC ceramic, the material is mainly removed by end ED milling at rough machining mode, whereas it is mainly removed by mechanical grinding at finish machining mode. Moreover, the material from the tool can transfer to the workpiece, and a combination reaction takes place during machining.

An Experimental Study on Mechanical Modeling of Ceramics Based on Microstructure

Directory of Open Access Journals (Sweden)

Ya-Nan Zhang

2015-11-01

Full Text Available The actual grinding result of ceramics has not been well predicted by the present mechanical models. No allowance is made for direct effects of materials microstructure and almost all the mechanical models were obtained based on crystalline ceramics. In order to improve the mechanical models of ceramics, surface grinding experiments on crystalline ceramics and non-crystalline ceramics were conducted in this research. The normal and tangential grinding forces were measured to calculate single grit force and specific grinding energy. Grinding surfaces were observed. For crystalline alumina ceramics, the predictive modeling of normal force per grit fits well with the experimental result, when the maximum undeformed chip thickness is less than a critical depth, which turns out to be close to the grain size of alumina. Meanwhile, there is a negative correlation between the specific grinding energy and the maximum undeformed chip thickness. With the decreasing maximum undeformed chip thickness, the proportions of ductile removal and transgranular fracture increase. However, the grinding force models are not applicable for non-crystalline ceramic fused silica and the specific grinding energy fluctuates irregularly as a function of maximum undeformed chip thickness seen from the experiment.

Effect of grinding and heat treatment on the mechanical behavior of zirconia ceramic

Directory of Open Access Journals (Sweden)

Gabriela Freitas RAMOS

2016-01-01

Full Text Available Abstract The present study investigated the effect of grinding on roughness, flexural strength, and reliability of a zirconia ceramic before and after heat treatment. Seven groups were tested (n = 15: a control group (labeled CG, untreated, and six groups of samples ground with diamond discs, simulating diamond burs, with grits of 200 µm (G80; 160 µm (G120, and 25 µm (G600, either untreated or heat-treated at 1200°C for 2 h (labeled A. Yttria tetragonal zirconia polycrystal discs were manufactured, ground, and submitted to roughness and crystalline phase analyses before the biaxial flexural strength test. There was no correlation between roughness (Ra and Rz and flexural strength. The reliability of the materials was not affected by grinding or heat treatment, but the characteristic strength was higher after abrasion with diamond discs, irrespective of grit size. The X-ray diffraction data showed that grinding leads to a higher monoclinic (m phase content, whereas heat treatment produces reverse transformation, leading to a fraction of m-phase in ground samples similar to that observed in the control group. However, after heat treatment, only the G80A samples presented strength similar to that of the control group, while the other groups showed higher strength values. When zirconia pieces must be adjusted for clinical use, a smoother surface can be obtained by employing finer-grit diamond burs. Moreover, when the amount of monoclinic phase is related to the degradation of zirconia, the laboratory heat treatment of ground pieces is indicated for the reverse transformation of zirconia crystals.

Ceramic technology report. Semi-annual progress report, April 1994--September 1994

Energy Technology Data Exchange (ETDEWEB)

Johnson, D.R.

1995-06-01

The Ceramic Technology Project was originally developed by the Department of Energy`s Office of Transportation Systems (OTS) in Energy Efficiency and Renewable Energy. This project, part of the OTS`s Materials Development Program, was developed to meet the ceramic technology requirements of the OTS`s automotive technology programs. Significant accomplishments in fabricating ceramic components for the Department of Energy (DOE), National Aeronautics and Space Administration (NASA), and Department of Defense (DoD) advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. However, these programs have also demonstrated that additional research is needed in materials and processing development, design methodology, and data base and life prediction before industry will have a sufficient technology base from which to produce reliable cost-effective ceramic engine components commercially. In response to extensive input from industry, the plan is to extend the engine types which were previously supported (advanced gas turbine and low-heat-rejection diesel engines) to include near-term (5-10 years) applications in conventional automobile and diesel truck engines. To facilitate the rapid transfer of this technology to U.S. industry, the major portion of the work is being done in the ceramic industry, with technological support from government laboratories, other industrial laboratories, and universities. A systematic approach to reducing the cost of components is envisioned. The work elements are as follows: economic cost modeling, ceramic machining, powder synthesis, alternative forming and densification processes, yield improvement, system design studies, standards development, low-expansion ceramics, and testing and data base development.

Strength and residual stress of Mg-PSZ after grinding

NARCIS (Netherlands)

van den Berg, P.H.J.; With, de G.

1993-01-01

The influence of grinding with two grinding wheels, differing mainly in diamond-grain size, on the properties of MgO-partially stabilized ZrO2 ceramics (Mg-PSZ) was examd. The residual stress, the amt. of monoclinic zirconia, and the strength of the material were detd. From these measurements, depth

Towards High Productivity in Precision Grinding

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W. Brian Rowe

2018-04-01

Full Text Available Over the last century, substantial advances have been made, based on improved understanding of the requirements of grinding processes, machines, control systems, materials, abrasives, wheel preparation, coolants, lubricants, and coolant delivery. This paper reviews a selection of areas in which the application of scientific principles and engineering ingenuity has led to the development of new grinding processes, abrasives, tools, machines, and systems. Topics feature a selection of areas where relationships between scientific principles and new techniques are yielding improved productivity and better quality. These examples point towards further advances that can fruitfully be pursued. Applications in modern grinding technology range from high-precision kinematics for grinding very large lenses and reflectors through to medium size grinding machine processes and further down to grinding very small components used in micro electro-mechanical systems (MEMS devices. The importance of material issues is emphasized for the range of conventional engineering steels, through to aerospace materials, ceramics, and composites. It is suggested that future advances in productivity will include the wider application of artificial intelligence and robotics to improve precision, process efficiency, and features required to integrate grinding processes into wider manufacturing systems.

12 CFR 411.600 - Semi-annual compilation.

Science.gov (United States)

2010-01-01

... 12 Banks and Banking 4 2010-01-01 2010-01-01 false Semi-annual compilation. 411.600 Section 411.600 Banks and Banking EXPORT-IMPORT BANK OF THE UNITED STATES NEW RESTRICTIONS ON LOBBYING Agency Reports § 411.600 Semi-annual compilation. (a) The head of each agency shall collect and compile the...

Grinding Si3N4 Powder In Si3N4 Equipment

Science.gov (United States)

Herbell, Thomas P.; Freedman, Marc R.; Kiser, James D.

1989-01-01

Three methods of grinding compared. Report based on study of grinding silicon nitride powder in preparation for sintering into solid ceramic material. Attrition, vibratory, and ball mills lined with reaction-bonded silicon nitride tested. Rates of reduction of particle sizes and changes in chemical compositions of powders measured so grinding efficiences and increases in impurity contents from wear of mills and media evaluated for each technique.

Adhesive wear mechanism under combined electric diamond grinding

Directory of Open Access Journals (Sweden)

Popov Vyacheslav

2017-01-01

Full Text Available The article provides a scientific substantiation of loading of metal-bond diamond grinding wheels and describes the mechanism of contact interaction (interlocking of wheels with tool steel as well as its general properties having an influence on combined electric diamond grinding efficiency. The study concluded that a loaded layer can be formed in a few stages different by nature. It is known, that one of the causes of grinding degradation is a continuous loading of active grits (abrasive grinding tool by workpiece chips. It all affects the diamond grinding wheels efficiency and grinding ability with a result in increase of tool pressure, contact temperature and wheels specific removal rate. Science has partially identified some various methods to minimize grinding wheel loading, however, as to loading of metal-bond diamond grinding wheels the search is still in progress. Therefore, research people have to state, that in spite of the fact that the wheels made of cubic boron nitride are of little use as applied to ceramic, ultrahard, hard-alloyed hard-to-machine and nano-materials of the time, but manufactures have to apply cubic boron nitride wheels wherein diamond ones preferable.

Single Side Electrolytic In-Process Dressing (ELID) Grinding with Lapping Kinematics of Silicon Carbide

Science.gov (United States)

Khoshaim, Ahmed Bakr

The demand for Silicon Carbide ceramics (SiC) has increased significantly in the last decade due to its reliable physical and chemical properties. The silicon carbide is widely used for aerospace segments in addition to many uses in the industry. Sometimes, a single side grinding is preferable than conventional grinding, for it has the ability to produce flat ceramics. However, the manufacturing cost is still high because of the high tool wear and long machining time. Part of the solution is to use electrolytic in process dressing (ELID) to reduce the processing time. The study on ELID single side grinding of ceramics has never been attempted before. The study involves four variables with three levels each. One of the variables, which is the eccentricity, is being investigated for the first time on ceramics. A full factorial design, for both the surface roughness and material removal rate, guides to calculate mathematical models that can predict future results. Three grinding wheel mesh sizes are used. An investigation of the influence of different grain size on the results can then be evaluated. The kinematics of the process was studied based on eccentricity in order to optimize the pattern of the diamond grains. The experiment is performed with the assist of the proposed specialized ELID fluid, TRIM C270E.

Semi-annual Sq-variation in solar activity cycle

Science.gov (United States)

Pogrebnoy, V.; Malosiev, T.

The peculiarities of semi-annual variation in solar activity cycle have been studied. The data from observatories having long observational series and located in different latitude zones were used. The following observatories were selected: Huancayo (magnetic equator), from 1922 to 1959; Apia (low latitudes), from 1912 to 1961; Moscow (middle latitudes), from 1947 to 1965. Based on the hourly values of H-components, the average monthly diurnal amplitudes (a difference between midday and midnight values), according to five international quiet days, were computed. Obtained results were compared with R (relative sunspot numbers) in the ranges of 0-30R, 40-100R, and 140-190R. It was shown, that the amplitude of semi-annual variation increases with R, from minimum to maximum values, on average by 45%. At equatorial Huancayo observatory, the semi-annual Sq(H)-variation appears especially clearly: its maximums take place at periods of equinoxes (March-April, September-October), and minimums -- at periods of solstices (June-July, December-January). At low (Apia observatory) and middle (Moscow observatory) latitudes, the character of semi-annual variation is somewhat different: it appears during the periods of equinoxes, but considerably less than at equator. Besides, with the growth of R, semi-annual variation appears against a background of annual variation, in the form of second peaks (maximum in June). At observatories located in low and middle latitudes, second peaks become more appreciable with an increase of R (March-April and September-October). During the periods of low solar activity, they are insignificant. This work has been carried out with the support from International Scientific and Technology Center (Project #KR-214).

Ultrasonic grinding of optical materials

Science.gov (United States)

Cahill, Michael; Bechtold, Michael; Fess, Edward; Stephan, Thomas; Bechtold, Rob

2017-10-01

Hard ceramic optical materials such as sapphire, ALON, Spinel, PCA, or Silicon Carbide can present a significant challenge in manufacturing precision optical components due to their tough mechanical properties. These are also the same mechanical properties that make them desirable materials when used in harsh environments. Slow processing speeds, premature tool wear, and poor surface quality are common results of the tough mechanical properties of these materials. Often, as a preparatory stage for polishing, the finish of the ground surface greatly influences the polishing process and the resulting finished product. To overcome these challenges, OptiPro Systems has developed an ultrasonic assisted grinding technology, OptiSonic, which has been designed for the precision optics and ceramics industry. OptiSonic utilizes a custom tool holder designed to produce oscillations, in microns of amplitude, in line with the rotating spindle. A software package, IntelliSonic, is integral to the function of this platform. IntelliSonic can automatically characterize tooling during setup to identify and select the ideal resonant peak which to operate at. Then, while grinding, IntelliSonic continuously adjusts the output frequency for optimal grinding efficiency while in contact with the part. This helps maintain a highly consistent process under changing load conditions for a more precise surface. Utilizing a variety of instruments, tests have proven to show a reduction in force between tool and part by up to 50%, while increasing the surface quality and reducing tool wear. This paper will present the challenges associated with these materials and solutions created to overcome them.

Application of focus-variation Technique in Measurements of Ultrasonic Vibrations of Grinding pins

Directory of Open Access Journals (Sweden)

Wdowik Roman

2015-01-01

Full Text Available The paper presents the application of focus-variation technique in measurements of ultrasonic vibrations of grinding pins. Ultrasonic vibrations of tools are applied in ultrasonic assisted grinding. Their measurements are significant for development of this hybrid machining process. Alumina and zirconia ceramic materials in the final fired state were machined in experiments which are known as scratch tests. Diamond grinding pin was used as a tool to machine scratches. Marks of diamond grains, left on the surface of workpieces after machining process, were investigated using The Infinite Focus Real 3D optical microscope. Focus-variation is the principle of operation of this microscope. Investigations concerned possibilities of measurements of an amplitude of axial and radial vibrations in the case of two ceramic materials. Results of performed measurements are presented and discussed for selected machining parameters.

Grinding media of Zr O2-Y2 O3

International Nuclear Information System (INIS)

Ussui, V.; Leitao, F.; Paschoal, J.O.A.

1994-01-01

This paper describes an experiment carried out to test Yttria 3 mol% stabilized zirconia as a grinding media. The Powders were produced in experimental operations of a wet chemical coprecipitation process at the Zirconium Pilot Plant in IPEN. The stabilised zirconia powders obtained were cold pressed in to cylindrical shapes and sintered at 1500 0 C for hour. The ceramics produced presented good wear resistance and were found to be efficient as zirconia powders grinding media. (author)

Cylindrical plunge grinding of difficult to grind materials

International Nuclear Information System (INIS)

Nakajima, Toshikatsu; Uno, Yoshiyuki; Kayahara, Masayuki.

1983-01-01

Cylindrical plunge grinding processes of titanium alloy and nickel-base superalloys with various kinds of conventional grinding wheels, which are known as difficult to grind materials, are experimentally investigated, analyzing size generation process, grinding force, surface roughness, wheel wear, grinding ratio and so on. For grinding titanium alloy Ti-6Al-4V, GC grinding wheel yields most superior grinding results which leads to lower grinding force, smaller residual stock, less wheel wear and higher grinding ratio up to about 3 with GC 80 L 9 V wheel. Then, for grinding nickelbase superalloys Waspaloy and Rene 41, WA 150 L 9 V wheel yields better grinding results in surface roughness, wheel wear, grinding ratio without chatter vibration though grinding force is higher, and the grinding ratio about 3 is obtained. Furthermore, higher plunge speed and speed ratio result in higher grinding efficiency though grinding force, surface roughness, wheel wear increase for grinding titanium alloy and nickel-base superalloys. (author)

Comparison of different grinding procedures on the flexural strength of zirconia.

Science.gov (United States)

Işeri, Ufuk; Ozkurt, Zeynep; Yalnız, Ayşe; Kazazoğlu, Ender

2012-05-01

The surface of zirconia ceramic is damaged during grinding, which may affect the mechanical properties of the material. The purpose of this study was to compare the biaxial flexural strength of zirconia after different grinding procedures and to measure the temperature rise from grinding. Forty disk-shaped zirconia specimens (15 × 1.2 mm) with a smaller disk in the center of each disk (1 × 3 mm) were divided into 4 groups (n=10). The specimens were ground with a high-speed handpiece and micromotor with 2 different grinding protocols, continual grinding and periodic grinding (10 seconds grinding with 10 seconds duration), until the smaller disk was removed. Control specimens without the center disk (n=10) were analyzed without grinding. The biaxial flexural strengths of the disks were determined in a universal testing machine at a crosshead speed of 0.5 mm/min. The fracture strength (MPa) was recorded, and the results were analyzed using a 1-way ANOVA, Tukey HSD test, Student's t test, and Pearson correlation test (α=05). All grinding procedures significantly decreased flexural strength (Pmicromotor groups (718 MPa). The temperature values obtained from micromotor grinding (127°C) were significantly higher than those from high-speed handpiece grinding (63°C) (P<.01). Grinding zirconia decreased flexural strength. Zirconia material ground with a high-speed handpiece run continually caused the least reduction in flexural strength. Copyright © 2012 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

The Study on Grinding Ratio in Form Grinding with White Fused Alumina (WA) Grinding Wheels

Science.gov (United States)

Junming, Wang; Jiong, Wang; Deyuan, Lou

2018-03-01

The study is carried out based on an experiment of form grinding spur rack with white fused alumina (WA) grinding wheels. In the experiment, SOV-3020A type tri-axial image mapper is utilized to measure the profile of the tooth space in the rack, and the curve equations between the sectional area of the tooth space and the tooth sequence under different grinding depths are established by nonlinear curve regress using software of origin8.0. Then, it deduces the prediction equations for current grinding ratio and cumulative grinding ratio under different grinding depths. The result shows that the grinding ratio is exponential decline relationship with the increase of the number of the tooth to be ground under the same grinding depth, and the decline speed is fast in the initial stage. With the increase of grinding depth, the grinding ratio increases gradually. The cumulative grinding ratio is about twice as high as the current grinding ratio. Thus, large grinding depth is generally used in rough grinding to improve grinding efficiency.

16th semi annual report

International Nuclear Information System (INIS)

1980-08-01

The 16th semi-annual report 1979/2 is a description of work within the Nuclear Safety Project performed in the second six month of 1979 in the nuclear safety field by KfK institutes and departments and by external institutions on behalf of KfK. The chosen kind of this report is that of short summaries, containing the topics: work performed, results obtained, plans for future work. (orig.) [de

Grinding Wheel Profile

Science.gov (United States)

2004-01-01

This graphic dubbed by engineers as the 'Grinding Wheel Profile' is the detective's tool used by the Opportunity team to help them understand one of the processes that formed the interior of a rock called 'McKittrick.' Scientists are looking for clues as to how layers, grains and minerals helped create this rock, and the engineers who built the rock abrasion tool (RAT) wanted to ensure that their instrument's handiwork did not get confused with natural processes.In the original microscopic image underlaying the graphics, engineers and scientists noticed 'layers' or 'scratches' on the spherical object nicknamed 'blueberry' in the lower right part of the image. The designers of the rock abrasion tool noticed that the arc length and width of the scratches were similar to the shape and size of the rock abrasion tool's grinding wheel, which is made out of a pad of diamond teeth.The scrapes on the bottom right blueberry appear to be caused by the fact that the berry got dislodged slightly and its surface was scraped with the grinding pad. In this image, the largest yellow circle is the overall diameter of the hole ground by the rock abrasion tool and the largest yellow rectangular shape is the area of the grinding wheel bit. The smaller yellow semi-circle is the path that the center of the grinding tool follows. The orange arrow arcing around the solid yellow circle (center of grinding tool) indicates the direction that the grinding tool spins around its own center at 3,000 revolutions per minute. The tool simultaneously spins in an orbit around the center of the hole, indicated by the larger orange arrow to the left.The grinding tool is 22 millimeters (0.9 inches) in length and the actual grinding surface, which consists of the diamond pad, is 1.5 millimeters (0.06 inches) in length, indicated by the two smaller rectangles. You can see that the smaller bottom rectangle fits exactly the width of the scrape marks.The grooves on the blueberry are also the same as the

Strength characterization of tubular ceramic materials by flexure of semi-cylindrical specimens

DEFF Research Database (Denmark)

Kwok, Kawai; Kiesel, Lutz; Frandsen, Henrik Lund

2014-01-01

Mechanical strength at elevated temperatures and operating atmospheres needs to be characterized during development of tubular ceramic components for advanced energy technologies. Typical procedures are time-consuming because a large number of tests are required for a reliable statistical strength...... characterization and every specimen has to be subjected to the process conditions individually. This paper presents an efficient strength characterization methodology for tubular ceramics. The methodology employs flexure of semi-cylindrical specimens as the strength test and implements the tests within a facility...... conducted on oxygen transport membrane materials at room temperature and 850°C....

Surface quality prediction model of nano-composite ceramics in ultrasonic vibration-assisted ELID mirror grinding

Energy Technology Data Exchange (ETDEWEB)

Zhao, Bo; Chen, Fan; Jia, Xiao-feng; Zhao, Chong-yang; Wang, Xiao-bo [Henan Polytechnic University, Jiaozuo (China)

2017-04-15

Ultrasonic vibration-assisted Electrolytic in-process dressing (ELID) grinding is a highly efficient and highly precise machining method. The surface quality prediction model in ultrasonic vibration-assisted ELID mirror grinding was studied. First, the interaction between grits and workpiece surface was analyzed according to kinematic mechanics, and the surface roughness model was developed. The variations in surface roughness under different parameters was subsequently calculated and analyzed by MATLAB. Results indicate that compared with the ordinary ELID grinding, ultrasonic vibration-assisted ELID grinding is superior, because it has more stable and better surface quality and has an improved range of ductile machining.

The influence of grinding oil viscosity on grinding heat and burn damage in creep-feed grinding{copyright}

Energy Technology Data Exchange (ETDEWEB)

Zhen-Change Liu [Shandong Univ. of Technology, Jinan (China); Abe, Satoshi; Noda, Masahiro [Yushiro Chemical Industry Co. Ltd., Kanagawa (Japan)

1995-08-01

Grinding oils are widely used in precision grinding, such as tool grinding, thread grinding and gear grinding, during which processes grinding burn is the most prevalent damage affecting the integrity of ground surface. This paper discusses the influence of oil viscosity on grinding heat and burn damage in creep-feed-grinding. Experimental results indicated that, under lighter grinding conditions, the effects of oil viscosity was not observed, but under heavy grinding conditions grinding burn occurred when using low viscosity oil. When the viscosity of the oil was increased, grinding heat and burn damage tended to be reduced. As the viscosity was increased to a certain level, grinding burn reduction, by further increasing the viscosity, became less while other problems such as much higher oil pump noise and reduced oil flow occurred. It is clear that a viscosity limit exists for given grinding conditions. 5 refs., 4 figs., 3 tabs.

Ionospheric F2-Layer Semi-Annual Variation in Middle Latitude by Solar Activity

Directory of Open Access Journals (Sweden)

Yoon-Kyung Park

2010-12-01

Full Text Available We examine the ionospheric F2-layer electron density variation by solar activity in middle latitude by using foF2 observed at the Kokubunji ionosonde station in Japan for the period from 1997 to 2008. The semi-annual variation of foF2 shows obviously in high solar activity (2000-2002 than low solar activity (2006-2008. It seems that variation of geomagnetic activity by solar activity influences on the semi-annual variation of the ionospheric F2-layer electron density. According to the Lomb-Scargle periodogram analysis of foF2 and Ap index, interplanetary magnetic field (IMF Bs (IMF Bz <0 component, solar wind speed, solar wind number density and flow pressure which influence the geomagnetic activity, we examine how the geomagnetic activity affects the ionospheric F2-layer electron density variation. We find that the semi-annual variation of daily foF2, Ap index and IMF Bs appear clearly during the high solar activity. It suggests that the semi-annual variation of geomagnetic activity, caused by Russell-McPherron effect, contributes greatly to the ionospheric F2-layer semi-annual electron density variation, except dynamical effects in the thermosphere.

13 CFR 146.600 - Semi-annual compilation.

Science.gov (United States)

2010-01-01

... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Semi-annual compilation. 146.600 Section 146.600 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION NEW RESTRICTIONS ON LOBBYING.... (c) Information that involves intelligence matters shall be reported only to the Select Committee on...

Finishing procedures action on mechanical characteristics of pressed ceramics

Directory of Open Access Journals (Sweden)

Mohamed Abdel Moniem Ahmed

2018-06-01

Conclusions& significance: Grinding & finishing procedures of pressed ceramics showed significant effect Of drill speed and polishing technique over flexural strength, As Grinding with no finishing and polishing procedure showed lowest flexural Strength values followed by finishing and polishing procedure followed by finishing and polishing with polishing paste procedure.

2. Semi-annual progress report 1980, no 17

International Nuclear Information System (INIS)

1981-01-01

This semi-annual report deals with the experimental research carried out at the Departement de Recherche Fondamentale de Grenoble (fission, nuclear spectroscopy, heavy ion reactions, physical metallurgy, magnetism, organic molecules, theoretical chemistry, molecular physical chemistry, cellular biology, vegetal biology) [fr

Development of Advanced Ceramic Manufacturing Technology; FINAL

International Nuclear Information System (INIS)

Pujari, V.K.

2001-01-01

Advanced structural ceramics are enabling materials for new transportation engine systems that have the potential for significantly reducing energy consumption and pollution in automobiles and heavy vehicles. Ceramic component reliability and performance have been demonstrated in previous U.S. DOE initiatives, but high manufacturing cost was recognized as a major barrier to commercialization. Norton Advanced Ceramics (NAC), a division of Saint-Gobain Industrial Ceramics, Inc. (SGIC), was selected to perform a major Advanced Ceramics Manufacturing Technology (ACMT) Program. The overall objectives of NAC's program were to design, develop, and demonstrate advanced manufacturing technology for the production of ceramic exhaust valves for diesel engines. The specific objectives were (1) to reduce the manufacturing cost by an order of magnitude, (2) to develop and demonstrate process capability and reproducibility, and (3) to validate ceramic valve performance, durability, and reliability. I n order to achieve these objectives, NAC, a leading U.S. advanced ceramics component manufacturer, assembled a multidisciplinary, vertically integrated team. This team included: a major diesel engine builder, Detroit Diesel Corporation (DDC); a corporate ceramics research division, SGIC's Northboro R and D Center; intelligent processing system developers, BDM Federal/MATSYS; a furnace equipment company, Centorr/Vacuum Industries; a sintering expert, Wittmer Consultants; a production OEM, Deco-Grand; a wheel manufacturer and grinding operation developer, Norton Company's Higgins Grinding Technology Center (HGTC); a ceramic machine shop, Chand Kare Technical Ceramics; and a manufacturing cost consultant, IBIS Associates. The program was divided into four major tasks: Component Design and Specification, Component Manufacturing Technology Development, Inspection and Testing, and Process Demonstration

Is annual recharge coefficient a valid concept in arid and semi-arid regions?

Directory of Open Access Journals (Sweden)

Y. Cheng

2017-10-01

Full Text Available Deep soil recharge (DSR (at depth greater than 200 cm is an important part of water circulation in arid and semi-arid regions. Quantitative monitoring of DSR is of great importance to assess water resources and to study water balance in arid and semi-arid regions. This study used a typical bare land on the eastern margin of Mu Us Sandy Land in the Ordos Basin of China as an example to illustrate a new lysimeter method of measuring DSR to examine if the annual recharge coefficient is valid or not in the study site, where the annual recharge efficient is the ratio of annual DSR over annual total precipitation. Positioning monitoring was done on precipitation and DSR measurements underneath mobile sand dunes from 2013 to 2015 in the study area. Results showed that use of an annual recharge coefficient for estimating DSR in bare sand land in arid and semi-arid regions is questionable and could lead to considerable errors. It appeared that DSR in those regions was influenced by precipitation pattern and was closely correlated with spontaneous strong precipitation events (with precipitation greater than 10 mm other than the total precipitation. This study showed that as much as 42 % of precipitation in a single strong precipitation event can be transformed into DSR. During the observation period, the maximum annual DSR could make up 24.33 % of the annual precipitation. This study provided a reliable method of estimating DSR in sandy areas of arid and semi-arid regions, which is valuable for managing groundwater resources and ecological restoration in those regions. It also provided strong evidence that the annual recharge coefficient was invalid for calculating DSR in arid and semi-arid regions. This study shows that DSR is closely related to the strong precipitation events, rather than to the average annual precipitation, as well as the precipitation patterns.

modeling grinding modeling grinding processes as micro processes

African Journals Online (AJOL)

eobe

industrial precision grinding processes are cylindrical, center less and ... Several model shave been proposed and used to study grinding ..... grinding force for the two cases were 9.07237N/mm ..... International Journal of Machine Tools &.

The Influence of Wet Dressing of Grinding Wheel on the Grinding Performance

OpenAIRE

重松, 日出見; 冨田, 進

1989-01-01

Experiments on the relation between the form of working plane of grinding wheel which was formed by dressing, and the grinding performance of working plane of grinding wheel in the early stage of grinding, were carried out supplying the same grinding fluid in dressing time and grinding time. As a result, it was found that the difference of the action or the effect of grinding fluids on the working plane of grinding fluid were related to the grinding performance in the early stage of grinding....

Fabrication of a 40-inch diameter ceramic to metal seal for PLT

International Nuclear Information System (INIS)

Lewin, G.; Mullaney, D.

1976-01-01

The design and fabrication details for the ceramic to metal seal for PLT are presented. The method used for the successful casting and firing of the 90% Al 2 O 3 ceramic body and the subsequent grinding and brazing of the ceramic to 430 S.S. are discussed

Grinding assembly, grinding apparatus, weld joint defect repair system, and methods

Science.gov (United States)

Larsen, Eric D.; Watkins, Arthur D.; Bitsoi, Rodney J.; Pace, David P.

2005-09-27

A grinding assembly for grinding a weld joint of a workpiece includes a grinder apparatus, a grinder apparatus includes a grinding wheel configured to grind the weld joint, a member configured to receive the grinding wheel, the member being configured to be removably attached to the grinder apparatus, and a sensor assembly configured to detect a contact between the grinding wheel and the workpiece. The grinding assembly also includes a processing circuitry in communication with the grinder apparatus and configured to control operations of the grinder apparatus, the processing circuitry configured to receive weld defect information of the weld joint from an inspection assembly to create a contour grinding profile to grind the weld joint in a predetermined shape based on the received weld defect information, and a manipulator having an end configured to carry the grinder apparatus, the manipulator further configured to operate in multiple dimensions.

7th REGENT semi-annual report

International Nuclear Information System (INIS)

Schlechtendahl, E.G.

1975-08-01

The project REGENT (German acronym for CAD, computer aided design) was started early 1972 by the Institut fuer Reaktorentwicklung. The seventh semi-annual progress report summarizes the results achieved up to March 31, 1975, in particular with respect to the development of the REGENT system nucleus and its application for the first REGENT subsystems. The development of the REGENT nucleus and of a graphical subsystem has become a part of the project CAD since mid 1974. Other subsystems are being developed within the framework of the project PNS (Project Nuclear Safety). (orig.) [de

Tool grinding machine

Science.gov (United States)

Dial, Sr., Charles E.

1980-01-01

The present invention relates to an improved tool grinding mechanism for grinding single point diamond cutting tools to precise roundness and radius specifications. The present invention utilizes a tool holder which is longitudinally displaced with respect to the remainder of the grinding system due to contact of the tool with the grinding surface with this displacement being monitored so that any variation in the grinding of the cutting surface such as caused by crystal orientation or tool thickness may be compensated for during the grinding operation to assure the attainment of the desired cutting tool face specifications.

Grinding in lead-zinc concentrator Sasa – choice between different grinding media

OpenAIRE

Krstev, Boris

2004-01-01

In this paper will be present result obtained from investigation in the grinding circuit of the lead-zinc concentrator Sasa,using differen grindng media: • Litzkhun-Niederwipper Forged Steel grinding balls; • GSI LUCCHINI Moly-Cop Forged Steel grinding balls; • Cast steel grinding balls from Ukraina and Bulgaria; In the same time will be shown comparation between obtained parameters using different grinding balls specially: • Capacity of the grinding mill; • Particle size; ...

Crush Grinding

International Nuclear Information System (INIS)

Nguyen, T.Q.

2005-01-01

Crush Grinding is a special process used at the Kansas City Plant to finish stem sections of reservoir products. In this process, a precise profile of the desired product is formed on a tungsten carbide roll. This roll slowly transfers a mirror image of the profile onto the grinding surface of a wheel. The transfer rate of the profile is between 0.001 and 0.010 inches per minute. Crush grinding is desirable since it provides consistent surface finishes and thin walls at a high production rate. In addition, it generates very sharp fillet radii. However, crush grinding is a complex process since many variables affect the final product. Therefore, the process requires more attention and knowledge beyond basic metal removal practices. While the Kansas City Plant began using these machines in 1995, a formal study regarding crush grinding has not been conducted there. In addition, very little literature is available in the grinding industry regarding this process. As a result, new engineers at the Kansas City Plant must learn the process through trial and error. The purpose of this document is to address this literature deficit while specifically promoting a better understanding of the stem crush grinding process at the Kansas City Plant.

Testing method for ceramic armour and bare ceramic tiles

NARCIS (Netherlands)

Carton, E.P.; Roebroeks, G.H.J.J.

2016-01-01

TNO developed an alternative, more configuration independent ceramic test method than the Depth-of-Penetration test method. In this alternative test ceramic tiles and ceramic based armour are evaluated as target without a semi-infinite backing layer. An energy approach is chosen to evaluate and rank

Testing method for ceramic armor and bare ceramic tiles

NARCIS (Netherlands)

Carton, E.P.; Roebroeks, G.H.J.J.

2014-01-01

TNO has developed an alternative, more configuration independent ceramic test method than the standard Depth-of-Penetration test method. In this test ceramic tiles and ceramic based armor are evaluated as target without a semi-infinite backing layer. An energy approach is chosen to evaluate and rank

Conduit grinding apparatus

Science.gov (United States)

Nachbar, Henry D.; Korytkowski, Alfred S.

1991-01-01

A grinding apparatus for grinding the interior portion of a valve stem receiving area of a valve. The apparatus comprises a faceplate, a plurality of cams mounted to an interior face of the faceplate, a locking bolt to lock the faceplate at a predetermined position on the valve, a movable grinder and a guide tube for positioning an optical viewer proximate the area to be grinded. The apparatus can either be rotated about the valve for grinding an area of the inner diameter of a valve stem receiving area or locked at a predetermined position to grind a specific point in the receiving area.

Improved tool grinding machine

Science.gov (United States)

Dial, C.E. Sr.

The present invention relates to an improved tool grinding mechanism for grinding single point diamond cutting tools to precise roundness and radius specifications. The present invention utilizes a tool holder which is longitudinally displaced with respect to the remainder of the grinding system due to contact of the tool with the grinding surface with this displacement being monitored so that any variation in the grinding of the cutting surface such as caused by crystal orientation or tool thicknesses may be compensated for during the grinding operation to assure the attainment of the desired cutting tool face specifications.

Specific grinding energy and surface roughness of nanoparticle jet minimum quantity lubrication in grinding

Directory of Open Access Journals (Sweden)

Zhang Dongkun

2015-04-01

Full Text Available Nanoparticles with the anti-wear and friction reducing features were applied as cooling lubricant in the grinding fluid. Dry grinding, flood grinding, minimal quantity of lubrication (MQL, and nanoparticle jet MQL were used in the grinding experiments. The specific grinding energy of dry grinding, flood grinding and MQL were 84, 29.8, 45.5 J/mm3, respectively. The specific grinding energy significantly decreased to 32.7 J/mm3 in nanoparticle MQL. Compared with dry grinding, the surface roughness values of flood grinding, MQL, and nanoparticle jet MQL were significantly reduced with the surface topography profile values reduced by 11%, 2.5%, and 10%, respectively, and the ten point height of microcosmic unflatness values reduced by 1.5%, 0.5%, and 1.3%, respectively. These results verified the satisfactory lubrication effects of nanoparticle MQL. MoS2, carbon nanotube (CNT, and ZrO2 nanoparticles were also added in the grinding fluid of nanoparticle jet MQL to analyze their grinding surface lubrication effects. The specific grinding energy of MoS2 nanoparticle was only 32.7 J/mm3, which was 8.22% and 10.39% lower than those of the other two nanoparticles. Moreover, the surface roughness of workpiece was also smaller with MoS2 nanoparticle, which indicated its remarkable lubrication effects. Furthermore, the role of MoS2 particles in the grinding surface lubrication at different nanoparticle volume concentrations was analyzed. MoS2 volume concentrations of 1%, 2%, and 3% were used. Experimental results revealed that the specific grinding energy and the workpiece surface roughness initially increased and then decreased as MoS2 nanoparticle volume concentration increased. Satisfactory grinding surface lubrication effects were obtained with 2% MoS2 nanoparticle volume concentration.

Surface grinding characteristics of ferrous metals under high-speed and speed-stroke grinding conditions

International Nuclear Information System (INIS)

Ghani, A.K.; Choudhury, I.A.; Ahim, M.B.

1999-01-01

Some ferrous metals have been ground under different conditions with high-speed and speed-stroke in surface grinding operation. The paper describes experimental investigation of grinding forces in grinding some ferrous metals with the application of cutting fluids. Grinding tests have been carried out on mild steel, assab steel and stainless steel with different combinations of down feed and cross feed. The wheel speed was 27 m/sec while the table speed was maintained at the maximum possible 25 m/min. The grindability has been evaluated by measuring the grinding forces, grinding ratio, and surface finish. Grinding forces have been plotted against down feed of the grinding wheel and cross feed of the table. It has been observed that the radial and tangential grinding forces in stainless steel were higher than those in assab steel and mild steel

The Effects of Wear upon the Axial Profile of a Grinding Wheel in the Construction of Innovative Grinding Wheels for Internal Cylindrical Grinding

OpenAIRE

Nadolny, K.; Słowiński, B.

2011-01-01

The article describes the effects of wear upon the axial profile of a grinding wheel in the axial cylindrical grinding processes. This mechanism was used to develop a grinding wheel with zone diversified structure made of microcrystalline sintered corundum abrasive grains and vitrifies bond. Such a grinding wheel is characterized by the conical rough grinding zone that is made by grains of a relatively large size, and a cylindrical finish grinding zone with grains of a smaller size and can be...

Surface roughness of zirconia for full-contour crowns after clinically simulated grinding and polishing.

Science.gov (United States)

Hmaidouch, Rim; Müller, Wolf-Dieter; Lauer, Hans-Christoph; Weigl, Paul

2014-12-01

The aim of this study was to evaluate the effect of controlled intraoral grinding and polishing on the roughness of full-contour zirconia compared to classical veneered zirconia. Thirty bar-shaped zirconia specimens were fabricated and divided into two groups (n=15). Fifteen specimens (group 1) were glazed and 15 specimens (group 2) were veneered with feldspathic ceramic and then glazed. Prior to grinding, maximum roughness depth (Rmax) values were measured using a profilometer, 5 times per specimen. Simulated clinical grinding and polishing were performed on the specimens under water coolant for 15 s and 2 N pressure. For grinding, NTI diamonds burs with grain sizes of 20 µm, 10 µm, and 7.5 µm were used sequentially. The ground surfaces were polished using NTI kits with coarse, medium and fine polishers. After each step, Rmax values were determined. Differences between groups were examined using one-way analysis of variance (ANOVA). The roughness of group 1 was significantly lower than that of group 2. The roughness increased significantly after coarse grinding in both groups. The results after glazing were similar to those obtained after fine grinding for non-veneered zirconia. However, fine-ground veneered zirconia had significantly higher roughness than venerred, glazed zirconia. No significant difference was found between fine-polished and glazed zirconia, but after the fine polishing of veneered zirconia, the roughness was significantly higher than after glazing. It can be concluded that for full-contour zirconia, fewer defects and lower roughness values resulted after grinding and polishing compared to veneered zirconia. After polishing zirconia, lower roughness values were achieved compared to glazing; more interesting was that the grinding of glazed zirconia using the NTI three-step system could deliver smooth surfaces comparable to untreated glazed zirconia surfaces.

The study of grinding patterns and factors influencing the grinding areas during sleep bruxism.

Science.gov (United States)

Tao, Jianxiang; Liu, Weicai; Wu, Junhua; Zhang, Xuying; Zhang, Yongting

2015-10-01

The purpose of this study is to investigate the grinding patterns and discuss the factors influencing the position relationship between intercuspal position (ICP) and grinding area during sleep bruxism. Lateral condylar inclination, inclination of lateral incisal path and freedom in long centric of thirty subjects were measured. The grinding patterns during sleep bruxism were recorded with a bruxism recording device, BruxChecker. The position relationship between ICP and the grinding area was examined. Spearman's rank correlation coefficient was used for correlation analysis between grinding area and free factors (grinding patterns, freedom in long centric and discrepancy between lateral condylar inclination and inclination of lateral incisal path). All 12 subjects with 0mm-freedom in long centric exhibited that ICP of both sides located within the grinding areas. 4 subjects showed that ICP of both sides located outside the grinding areas. There is a significant correlation between 0mm-freedom in long centric and ICP within the grinding areas (p grinding area. Copyright © 2015 Elsevier Ltd. All rights reserved.

Processing, microstructure, and mechanical properties of large-grained zirconium diboride ceramics

Energy Technology Data Exchange (ETDEWEB)

Neuman, Eric W.; Hilmas, Gregory E., E-mail: ghilmas@mst.edu; Fahrenholtz, William G.

2016-07-18

Zirconium diboride ceramics produced using commercial ZrB{sub 2} powders, and milled with zirconium diboride grinding media, were fabricated by hot-pressing at temperatures of 2100–2200 °C with hold times of 30–120 min. This ZrB{sub 2} exhibits no additional impurities typically introduced by milling with grinding media of differing composition. Microstructure analysis revealed grain sizes ranging from ~25 to ~50 µm along with ~3 vol% porosity. Flexure strength ranged from 335 to 400 MPa, elastic modulus from 490 to 510 GPa, fracture toughness from 2.7 to 3.2 MPa m{sup ½}, and hardness from 13.0 to 14.4 GPa. Strength limiting flaws were identified as surface grain pullout induced by machining. Elastic modulus and hardness were found to increase with decreasing porosity. Compared to the fine grained ceramics typically reported, large grain zirconium diboride ceramics exhibit higher than expected room temperature strengths.

AFM Surface Roughness and Topography Analysis of Lithium Disilicate Glass Ceramic

Directory of Open Access Journals (Sweden)

M. Pantić

2015-12-01

Full Text Available The aim of this study is presenting AFM analysis of surface roughness of Lithium disilicate glass ceramic (IPS e.max CAD under different finishing procedure (techniques: polishing, glazing and grinding. Lithium disilicate glass ceramics is all-ceramic dental system which is characterized by high aesthetic quality and it can be freely said that properties of material provide all prosthetic requirements: function, biocompatibility and aesthetic. Experimental tests of surface roughness were investigated on 4 samples with dimensions: 18 mm length, 14 mm width and 12 mm height. Contact surfaces of three samples were treated with different finishing procedure (polishing, glazing and grinding, and the contact surface of the raw material is investigated as a fourth sample. Experimental measurements were done using the Atomic Force Microscopy (AFM of NT-MDT manufacturers, in the contact mode. All obtained results of different prepared samples are presented in the form of specific roughness parameters (Rа, Rz, Rmax, Rq and 3D surface topography.

Fabrication of a miniature diamond grinding tool using a hybrid process of micro-EDM and co-deposition

International Nuclear Information System (INIS)

Chen, Shun-Tong; Lai, Yun-Cheng; Liu, Ching-Chang

2008-01-01

A novel miniature diamond grinding tool usable for the precise micro-grinding of miniature parts is presented. A hybrid process that combines 'micro-EDM' with 'precision co-deposition' is proposed. The metal substrate is micro-EDMed to a 50 µm diameter and micro diamonds with 0–2 µm grains are 'electroformed' on the substrate surface, producing a miniature multilayered grinding tool. Nickel and diamond act as binders and cutters, respectively. A partition plate with an array of drilled holes is designed to ensure good convection in the electroforming solution. The dispersion of diamond grains and displacement of nickel ions are noticeably improved. A miniature funnel mould enables the diamond grains to converge towards the cathode to increase their deposition probability on the substrate, thereby improving their distribution on the substrate surface. A micro ZrO 2 ceramic ferrule is finely ground by the developed grinding tool and then yields a surface roughness of R a = 0.085 µm. The proposed approach is applied during the final machining process

Effects of Different Grinding Methods on Morphological, Textural Properties and Pasting Profiles of MR220 Rice Flour

International Nuclear Information System (INIS)

Noorlaila Ahmad; Asmeda Rajab; Norziah Mohd Hani

2016-01-01

Three different grinding techniques (dry, semi-wet, and wet) were employed in rice flour production. Investigation on the effects of the grinding techniques on starch damage percentage, particle size distribution, pasting profiles, morphological and textural properties of rice flours produced were evaluated. Wet grinding resulted in significantly (p<0.05) has lower percentage of damaged starch (3.24 %) than other grinding methods. Morphological studies (microscopy and particle size analysis) have reflected significant differences among rice flours granule shapes. The granules displaying different shapes of polygonal, round and angular forms, with some as an individual granule while others tend to attached together. Wet grinding technique also yielded flour that exhibit significantly (p<0.05) with higher gel hardness (16.62 g). Pasting profiles showed that pasting temperature for rice flour produce using these three grinding methods varied between 80.15 - 80.42 degree Celcius. Results revealed that the three grinding techniques clearly affected the physicochemical properties of rice flour. The results from this study play an important role in the selection criteria of rice flour with desirable pasting and textural properties for manufacturing rice-based product. (author)

Mechanical activation of ceramic powders and its influence on the quality of the refractory linings

International Nuclear Information System (INIS)

Ceganac, Z.; Acimovic, Z.; Andric, Lj.; Petrov, M.; Mihajlovic, S.

2003-01-01

In the paper we present results of the investigation of the influence of mechanical activation of ceramic powders-talc and alumina, on the quality of refractory linings for casting applications. It is shown that additional fine grinding of ceramic powders increases the quality of the refractory lining. Grinding and activation of the particles with various granulations contributes to the creation of the homogenous continuous layer of refractory lining on the sand moulds and cores, as well as on the evaporating polystyrene patterns for applications in the Lost foam casting process. Refractory linings obtained within the activation of particles procedure have better adherence to moulds, cores and evaporating patterns. (Original)

Observation of domain patterns on a ferroelectric ceramic

International Nuclear Information System (INIS)

Ibrahim, R.C.; Zavaglia, C.A.C.

1992-01-01

In this work ferroelectric domain patterns are observed on a PZT-like ceramic material produced in Brazil. This material has tetragonal unit cell composing a perovskite type structure. The samples, after grinding and polishing, were chemically etched and observed on optical microscope and scanning electron microscope. (author)

Development of a Laser-Guided Deep-Hole Internal-Grinding Tool (Series 1) : Grinding Forces

OpenAIRE

Katsuki, Akio; Onikura, Hiromichi; Sajima, Takao; Park, Hyunkoo

2005-01-01

The laser-guided deep-hole internal grinding tool is developed to bore accurate and straight deep-holes with high surface quality. The tool consists of a grinding head, the front and rear actuators mounted on an actuator holder and a laser diode set in the back end of the holder. The grinding head consists of a diamond or CBN wheel, an air motor, and the piezoelectric actuators for the compensation of tool diameter. The grinding wheel is located eccentrically at the grinding head. The grindin...

Effect of Two Polishing Systems on Surface Roughness, Topography, and Flexural Strength of a Monolithic Lithium Disilicate Ceramic.

Science.gov (United States)

Mohammadibassir, Mahshid; Rezvani, Mohammad Bagher; Golzari, Hossein; Moravej Salehi, Elham; Fahimi, Mohammad Amin; Kharazi Fard, Mohammad Javad

2017-03-08

To evaluate the effect of overglazing and two polishing procedures on flexural strength and quality and quantity of surface roughness of a monolithic lithium disilicate ceramic computer-aided design (CAD) after grinding. This in vitro study was conducted on 52 partially crystalized bar-shaped specimens (16 × 4 × 1.6 mm) of monolithic lithium disilicate ceramic. The specimens were wet polished with 600-, 800-, and 1200-grit silicon carbide papers for 15 seconds using a grinding/polishing machine at a speed of 300 rpm. Then, the specimens were crystalized and glaze-fired in one step simultaneously and randomly divided into four groups of 13: (I) Glazing group (control); (II) Grinding-glazing group, subjected to grinding with red band finishing diamond bur (46 μm) followed by glazing; (III) Grinding-D+Z group, subjected to grinding and then polishing by coarse, medium, and fine diamond rubber points (D+Z); and (IV) Grinding-OptraFine group, subjected to grinding and then polishing with a two-step diamond rubber polishing system followed by a final polishing step with an OptraFine HP brush and diamond polishing paste. The surface roughness (Ra and Rz) values (μm) were measured by a profilometer, and the mean values were compared using one-way ANOVA and Tamhane's test (post hoc comparison). One specimen of each group was evaluated under a scanning electron microscope (SEM) for surface topography. The three-point flexural strength values of the bars were measured using a universal testing machine at a 0.5 mm/min crosshead speed and recorded. The data were analyzed using one-way ANOVA and Tamhane's test (α = 0.05). Statistically significant differences were noted among the experimental groups for Ra, Rz (p SEM analysis of polished surfaces revealed regular morphology with some striations. The OptraFine system created smoother and more uniform surfaces in terms of quantity (p < 0.03 for Ra, p < 0.01 for Rz) and quality of roughness compared to glazing. The flexural

Characterization of Bi2/3Cu3Ti4O12 ceramics synthesized by semi-wet route

Directory of Open Access Journals (Sweden)

Pooja Gautam

2016-12-01

Full Text Available Bi2/3Cu3Ti4O12 (BCTO ceramic was synthesized by the semi-wet route using metal nitrate solutions and solid TiO2 powder in a stoichiometric ratio. Fourier transform infrared (FTIR study of BCTO precursor powder and calcined ceramic showed the presence of alcoholic functional groups and the stretching band of Ti-O and Cu-O respectively. X-ray diffraction (XRD, scanning electron microscope (SEM and energy dispersive x-ray spectroscopy (EDX were employed to characterize the structure, surface morphology and purity of the sintered BCTO ceramic respectively. X-ray diffraction study confirmed the single phase formation of BCTO ceramic at 1073 K. The average dimension of grains calculated by SEM and AFM was found to be in the range of 0.73±0.2 µm with clear grain boundaries. Magnetic property was investigated over a wide temperature range 2–300 K at a magnetic field of 7 tesla. The Curie temperature was calculated by zero field cooled (MZFC and field cooled (MFC magnetization at 100 Oe applied field which was found to be 125 K. The sintered BCTO ceramic shows high dielectric constant (ε'=2.9×104 at 323 K and 100 Hz.

Grinding and polishing of conformal windows and domes

Science.gov (United States)

Fess, Edward; Ross, James; Matthews, Greg

2017-05-01

Conformal optics require special manufacturing techniques to produce them to optical tolerances. In many cases the materials used are very hard optical ceramics that present additional manufacturing challenges due to their hardness and grain structure. OptiPro has developed grinding technologies such as OptiSonic grinding, as well as sub-aperture polishing technologies like UltraForm Finishing (UFF) to manufacture these challenging components. We have also developed a custom computer aided manufacturing (CAM) software package, ProSurf, to generate the complex tool paths for both grinding and polishing processes. One of the main advantages of ProSurf over traditional CAM software packages is that it uses metrology feedback for deterministic corrections. The metrology input can be obtained from OptiPro's 5-axis UltraSurf metrology system, which is capable of measuring these complex shapes to sub-micron accuracies. Through the development of these technologies much work has been performed in creating, measuring and analyzing the alignment fiducials or datum's used to qualify the location of the optical surfaces. Understanding the sensitivity of the optical surface to any datum misalignment is critical to knowing not only where the part is in space, but how good the optical surfaces are to each other. Working with the optical designer to properly tolerance surfaces to these datums is crucial. This paper will present the technologies developed by OptiPro to manufacture conformal windows as well as information related to the optical surfaces sensitivity to datums and how accurately those datums can be measured.

Characterization of Al2O3-Co ceramic composite obtained by high energy mill

International Nuclear Information System (INIS)

Souza, J.L.; Assis, R.B. de; Carlos, E.M.; Oliveira, T.P.; Costa, F.A. da

2014-01-01

This work aims to characterize the ceramic composite Al 2 O3-Co obtained by high energy grinding. The composites were obtained by milling Al 2 O 3 and Co in a high energy mill at a speed of 400 rpm, in proportions of 5 to 20% Cobalt (Co). Ceramic composites with 5 and 20% cobalt were sintered at 1200 and 1300 ° C, with a 60-minute plateau and a heating rate of 10 ° C / min. The samples were characterized by X-ray diffraction (XRD), thermogravimetry and differential scanning calorimetry (TG / DSC) and scanning electron microscopy (SEM). The results show the significant effect of cobalt percentage and high energy grinding on the final properties of the Al 2 O 3 - Co ceramic composite, presenting satisfactory values for the composite with a 20% cobalt percentage, showing to be a promising material for application in cutting tools

High Performance Grinding and Advanced Cutting Tools

CERN Document Server

Jackson, Mark J

2013-01-01

High Performance Grinding and Advanced Cutting Tools discusses the fundamentals and advances in high performance grinding processes, and provides a complete overview of newly-developing areas in the field. Topics covered are grinding tool formulation and structure, grinding wheel design and conditioning and applications using high performance grinding wheels. Also included are heat treatment strategies for grinding tools, using grinding tools for high speed applications, laser-based and diamond dressing techniques, high-efficiency deep grinding, VIPER grinding, and new grinding wheels.

The effect of abrading and cutting instruments on machinability of dental ceramics.

Science.gov (United States)

Sakoda, Satoshi; Nakao, Noriko; Watanabe, Ikuya

2018-03-16

The aim was to investigate the effect of machining instruments on machinability of dental ceramics. Four dental ceramics, including two zirconia ceramics were machined by three types (SiC, diamond vitrified, and diamond sintered) of wheels with a hand-piece engine and two types (diamond and carbide) of burs with a high-speed air turbine. The machining conditions used were abrading speeds of 10,000 and 15,000 r.p.m. with abrading force of 100 gf for the hand-piece engine, and a pressure of 200 kPa and a cutting force of 80 gf for the air-turbine hand-piece. The machinability efficiency was evaluated by volume losses after machining the ceramics. A high-abrading speed had high-abrading efficiency (high-volume loss) compared to low-abrading speed in all abrading instruments used. The diamond vitrified wheels demonstrated higher volume loss for two zirconia ceramics than those of SiC and diamond sintered wheels. When the high-speed air-turbine instruments were used, the diamond points showed higher volume losses compared to the carbide burs for one ceramic and two zirconia ceramics with high-mechanical properties. The results of this study indicated that the machinability of dental ceramics depends on the mechanical and physical properties of dental ceramics and machining instruments. The abrading wheels show autogenous action of abrasive grains, in which ground abrasive grains drop out from the binder during abrasion, then the binder follow to wear out, subsequently new abrasive grains come out onto the instrument surface (autogenous action) and increase the grinding amount (volume loss) of grinding materials.

Comparison of Grinding Characteristics of Converter Steel Slag with and without Pretreatment and Grinding Aids

Directory of Open Access Journals (Sweden)

Jihui Zhao

2016-10-01

Full Text Available The converter steel slag cannot be widely used in building materials for its poor grindability. In this paper, the grinding characteristics of untreated and pretreated (i.e., magnetic separation steel slag were compared. Additionally, the grinding property of pretreated steel slag was also studied after adding grinding aids. The results show that the residues (i.e., oversize substance that passed a 0.9 mm square-hole screen can be considered as the hardly grinding phases (HGP and its proportion is about 1.5%. After the initial 20 min grinding, the RO phase (RO phase is a continuous solid solution which is composed of some divalent metal oxides, such as FeO, MgO, MnO, CaO, etc., calcium ferrite, and metallic iron phase made up most of the proportion of the HGP, while the metallic iron made up the most component after 70 min grinding. The D50 of untreated steel slag could only reach 32.89 μm after 50 min grinding, but that of pretreated steel slag could reach 18.16 μm after the same grinding time. The grinding efficiency of steel slag was obviously increased and the particle characteristics were improved after using grinding aids (GA, especially the particle proportions of 3–32 μm were obviously increased by 7.24%, 7.22%, and 10.63% after 40 min, 50 min, and 60 min grinding, respectively. This is mainly because of the reduction of agglomeration and this effect of GA was evidenced by SEM (scanning electron microscope images.

Grinding Fluid Jet Characteristics and Their Effect on a Gear Profile Grinding Process

Directory of Open Access Journals (Sweden)

Philip Geilert

2017-10-01

Full Text Available Profile gear grinding is characterized by a high level of achievable process performance and workpiece quality. However, the wide contact length between the workpiece and the grinding wheel is disadvantageous for the fluid supply to the contact zone and leads to the risk of locally burning the workpiece surface. For the reduction of both the thermal load and the risk of thermo-mechanical damage, the usage of a grinding fluid needs to be investigated and optimized. For this purpose, different kinds of grinding fluid nozzles were tested, which provide different grinding fluid jet characteristics. Through a specific design of the nozzles, it is possible to control the fluid flow inside the nozzle. It was found that this internal fluid flow directly influences the breakup of the coolant fluid jet. There are three groups of jet breakup (“droplet”, “wave & droplet”, and “atomization”. The first experimental results show that the influence of the jet breakup on the process performance is significant. The “wave & droplet” jet breakup can achieve a high process performance, in contrast to the “atomization” jet breakup. It can therefore be assumed that the wetting of the grinding wheel by the grinding fluid jet is significantly influenced by the jet breakup.

Grinding kinetics and equilibrium states

Science.gov (United States)

Opoczky, L.; Farnady, F.

1984-01-01

The temporary and permanent equilibrium occurring during the initial stage of cement grinding does not indicate the end of comminution, but rather an increased energy consumption during grinding. The constant dynamic equilibrium occurs after a long grinding period indicating the end of comminution for a given particle size. Grinding equilibrium curves can be constructed to show the stages of comminution and agglomeration for certain particle sizes.

Multi-scale structures and pasting characteristics of starch in whole-wheat flour treated by superfine grinding.

Science.gov (United States)

Niu, Meng; Zhang, Binjia; Jia, Caihua; Zhao, Siming

2017-11-01

The multi-scale structures and pasting properties of starch in WWF were investigated after superfine grinding. Five particle size distributions of WWF and their corresponding starch were obtained. The grinding process reduced the particle size of WWF and starch. However, a slight increase of fragments from starch granules was observed with enhanced grinding strength because of the small decrease in starch particle size and the existence of other WWF components that undertook some of shearing force and friction during grinding. A prominent reduction in starch crystallinity was resulted due to the destruction of crystalline structure by grinding. Small-angle X-ray scattering analyses indicated the disordering in starch semi-crystalline lamellae with thinner lamellae thickness. Additionally, the 13 C Nuclear Magnetic Resonance spectra demonstrated the alterations in starch chain conformation by varying peak areas of starch carbons (C1 and C4). Along with these structural changes, Starch pasting characteristics showed substantial variations, indicating decreased viscosities and higher pasting stability. The results suggest that the grinding treatments influenced the structures and pasting properties of starch even at a non-separated state, the changes in starch structures were related to the variations in starch gelatinization characteristics. Copyright © 2017 Elsevier B.V. All rights reserved.

Kinetics of Grinding of Secondary Serpentine Raw Material at Cascade Operating Mode

Directory of Open Access Journals (Sweden)

Marek Matik

2004-12-01

Full Text Available The paper deals with the grinding of secondary serpentine material from the Dobšiná´s heap in a ball ceramic mill. The raw material was pre-sieved to prepare fraction of +250 –1,000 µm that was fed to the mill. During batch experiment an amount of oversize on the screen with a mesh size of 200 µm was observed as a function of time. Two speed modes were tested. Firstly, it was the mode designed by mill producer implicit from the structure of milling stand equipped by electromotor, friction gear onto driving shaft with given diameter. The speed of this original alignment attains 40 rmp. Secondly, it was cascade speed mode according to the Haase´s equation, namely 53 rmp, achieved by enlargement of driving shaft diameter. As to winning of required final product 90 % –200 µm, increased speed resulted in the shortening of grinding time from 17.5 to15.7 hour.

Force characteristics in continuous path controlled crankpin grinding

Science.gov (United States)

Zhang, Manchao; Yao, Zhenqiang

2015-03-01

Recent research on the grinding force involved in cylindrical plunge grinding has focused mainly on steady-state conditions. Unlike in conventional external cylindrical plunge grinding, the conditions between the grinding wheel and the crankpin change periodically in path controlled grinding because of the eccentricity of the crankpin and the constant rotational speed of the crankshaft. The objective of this study is to investigate the effects of various grinding conditions on the characteristics of the grinding force during continuous path controlled grinding. Path controlled plunge grinding is conducted at a constant rotational speed using a cubic boron nitride (CBN) wheel. The grinding force is determined by measuring the torque. The experimental results show that the force and torque vary sinusoidally during dry grinding and load grinding. The variations in the results reveal that the resultant grinding force and torque decrease with higher grinding speeds and increase with higher peripheral speeds of the pin and higher grinding depths. In path controlled grinding, unlike in conventional external cylindrical plunge grinding, the axial grinding force cannot be disregarded. The speeds and speed ratios of the workpiece and wheel are also analyzed, and the analysis results show that up-grinding and down-grinding occur during the grinding process. This paper proposes a method for describing the force behavior under varied process conditions during continuous path controlled grinding, which provides a beneficial reference for describing the material removal mechanism and for optimizing continuous controlled crankpin grinding.

Causes of the mid-latitudinal daytime NmF2 semi-annual anomaly at solar minimum

Science.gov (United States)

Pavlov, A. V.

2018-04-01

Ionospheric ionosonde and radar observations and theoretical calculations of the F2-layer peak altitude, hmF2, and number density, NmF2, over Millstone Hill during winter, spring, summer, and autumn geomagnetically quiet time periods at low solar activity are used to study the causes of the observed daytime NmF2 semi-annual anomaly. It follows from the model simulations that this anomalous phenomenon arises in the ionosphere mainly as a result of seasonal variations of the following atmospheric parameters: (1) the plasma drift along geomagnetic field lines due to corresponding changes in neutral wind components, (2) temperature and number densities of the neutral atmosphere, and (3) an optical thickness of the atmosphere caused by the dependence of the solar zenith angle on the day of the year for the same solar local time. Seasonal variations of the production rate unexcited O+ ions due to chemical reactions involving electronically excited O+ ions contribute to the formation of the NmF2 semi-annual anomaly during the predominant part of the existence time of this anomalous phenomenon. However, these seasonal variations are not significant, and this mechanism should be considered only as an additional source of the NmF2 semi-annual anomaly during its time of existence. The reactions of unexcited O+ ions with vibrationally excited N2 and O2 cause only weak changes of NmF2 and these changes are close in magnitude at a given solar local time during the winter, spring, summer, and autumn daytime conditions under consideration. Ignoring these reactions cannot produce a significant impact on the formation of the NmF2 semi-annual anomaly.

Repair of pathology of structure with mortar to reject the red ceramics

International Nuclear Information System (INIS)

Santana, Claudeir de Souza; Santos, Juzelia

2010-01-01

The aim of this research is the use of the reject of red ceramic from an industry of bricks and tiles from the region of Cuiaba as mortar for repair of structural pathology, looking for their application to replace the sand and gravel in the process. The mortar produced restores a park bench made of concrete which seat was made of red ceramic and legs of soil-cement bricks. The reject of red ceramic used is from an industry in the region of Cuiaba, discarded at the end of the production process, ground in an appropriate granulometry to simulate a generic type of sand and gravel. Grinding processes were developed and various granulometric curves were drawned. The aggregates produced were characterized from the deposit until the final grinding according to ABNT norms in force, the specific area by BET, was used for microanalysis X-ray diffraction. ABNT standards were used to characterize and compare the results. The mortar produced proved to be adequate for the proposal restoration, it was consistent and cohesive. It was concluded that the mortar produced with recycled aggregate of red ceramic can be used in structural restoration in civil construction to replace the natural aggregate, with cost and environmental benefits. (author)

Grinding Wheel System

Science.gov (United States)

Malkin, Stephen; Gao, Robert; Guo, Changsheng; Varghese, Biju; Pathare, Sumukh

2003-08-05

A grinding wheel system includes a grinding wheel with at least one embedded sensor. The system also includes an adapter disk containing electronics that process signals produced by each embedded sensor and that transmits sensor information to a data processing platform for further processing of the transmitted information.

Nanometer, submicron and micron sized aluminum powder prepared by semi-solid mechanical stirring method with addition of ceramic particles

International Nuclear Information System (INIS)

Qin, X.H.; Jiang, D.L.; Dong, S.M.

2004-01-01

Composite powder, which is a mixture of Al/Al 2 O 3 composite particles and nanometer, submicron and micron sized aluminum powder, was prepared by semi-solid mechanical stirring method with addition of Al 2 O 3 ceramic particles. The ceramic particles have an average diameter of 80 μm and a volume fraction of 15% in the slurry. The methods used to measure the size distribution of particles greater than 50 μm and less than 50 μm were sieve analysis and photosedimentation, respectively. The surface morphology and transverse sections of the composite powder of different sizes were examined by scanning electron microscope (SEM), optical microscope and auger electron spectroscopy (AES). The results indicate that the composite powder prepared in present work have a wide size distribution ranging from less than 50-900 μm, and the aluminum particles and Al/Al 2 O 3 composite particles are separated and isolated. The particles greater than 200 μm and less than 50 μm are almost pure aluminum powder. The rate of conversion of ingot aluminum into particles less than 1 μm containing nanometer and submicron sizes is 1.777 wt.% in this work. The aluminum powder of different sizes has different shape and surface morphology, quasi-spherical in shape with rough surface for aluminum particles of micron scale, irregular in shape for aluminum particles of submicron scale, and quite close to a globular or an excellent globular in shape for aluminum particles of nanometer size. On the other hand, the surface of ceramic particle was coated by aluminum particles with maximum thickness less than 10 μm containing nanometer and submicron sizes as a single layer. It is suggested that the surface of ceramic particles can provide more nucleation sites for solidification of liquid aluminum and the nucleation of liquid aluminum can take place readily, grow and adhere on the surface of ceramic particles, although it is poorly wetted by the liquid aluminum and the semi-solid slurry can

Grinding Away Microfissures

Science.gov (United States)

Booth, Gary N.; Malinzak, R. Michael

1990-01-01

Treatment similar to dental polishing used to remove microfissures from metal parts without reworking adjacent surfaces. Any variety of abrasive tips attached to small motor used to grind spot treated. Configuration of grinding head must be compatible with configurations of motor and workpiece. Devised to eliminate spurious marks on welded parts.

FY2015 ceramic fuels development annual highlights

Energy Technology Data Exchange (ETDEWEB)

Mcclellan, Kenneth James [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

2015-09-22

Key challenges for the Advanced Fuels Campaign are the development of fuel technologies to enable major increases in fuel performance (safety, reliability, power and burnup) beyond current technologies, and development of characterization methods and predictive fuel performance models to enable more efficient development and licensing of advanced fuels. Ceramic fuel development activities for fiscal year 2015 fell within the areas of 1) National and International Technical Integration, 2) Advanced Accident Tolerant Ceramic Fuel Development, 3) Advanced Techniques and Reference Materials Development, and 4) Fabrication of Enriched Ceramic Fuels. High uranium density fuels were the focus of the ceramic fuels efforts. Accomplishments for FY15 primarily reflect the prioritization of identification and assessment of new ceramic fuels for light water reactors which have enhanced accident tolerance while also maintaining or improving normal operation performance, and exploration of advanced post irradiation examination techniques which will support more efficient testing and qualification of new fuel systems.

FY2016 Ceramic Fuels Development Annual Highlights

Energy Technology Data Exchange (ETDEWEB)

Mcclellan, Kenneth James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-01-24

Key challenges for the Advanced Fuels Campaign are the development of fuel technologies to enable major increases in fuel performance (safety, reliability, power and burnup) beyond current technologies, and development of characterization methods and predictive fuel performance models to enable more efficient development and licensing of advanced fuels. Ceramic fuel development activities for fiscal year 2016 fell within the areas of 1) National and International Technical Integration, 2) Advanced Accident Tolerant Ceramic Fuel Development, 3) Advanced Techniques and Reference Materials Development, and 4) Fabrication of Enriched Ceramic Fuels. High uranium density fuels were the focus of the ceramic fuels efforts. Accomplishments for FY16 primarily reflect the prioritization of identification and assessment of new ceramic fuels for light water reactors which have enhanced accident tolerance while also maintaining or improving normal operation performance, and exploration of advanced post irradiation examination techniques which will support more efficient testing and qualification of new fuel systems.

Surface grinding of intermetallic titanium aluminides

CERN Document Server

Gröning, Holger Andreas

2014-01-01

A deductive kinematic model of creep-feed and speed-stroke grinding processes is developed to identify possibilities to reduce the energy introduced into the workpiece. By computer tomography analysis and tactile measurements of the grinding wheel the pore volume and the static cutting edge number are determined and included in the model. Based on the kinematic model and the grinding wheel characteristics an analytical evaluation of the specific grinding energy for speed-stroke and creep-feed grinding is carried out. The deducted process design is evaluated in experimental investigations. The

Influence of Cooling Condition on the Performance of Grinding Hardened Layer in Grind-hardening

Science.gov (United States)

Wang, G. C.; Chen, J.; Xu, G. Y.; Li, X.

2018-02-01

45# steel was grinded and hardened on a surface grinding machine to study the effect of three different cooling media, including emulsion, dry air and liquid nitrogen, on the microstructure and properties of the hardened layer. The results show that the microstructure of material surface hardened with emulsion is pearlite and no hardened layer. The surface roughness is small and the residual stress is compressive stress. With cooling condition of liquid nitrogen and dry air, the specimen surface are hardened, the organization is martensite, the surface roughness is also not changed, but high hardness of hardened layer and surface compressive stress were obtained when grinding using liquid nitrogen. The deeper hardened layer grinded with dry air was obtained and surface residual stress is tensile stress. This study provides an experimental basis for choosing the appropriate cooling mode to effectively control the performance of grinding hardened layer.

Analysis on the grinding quality of palm oil fibers by using combined grinding equipment

Science.gov (United States)

Gan, H. L.; Gan, L. M.; Law, H. C.

2015-12-01

As known, Malaysia is the second largest palm oil producer worldwide after Indonesia, therefore indicating the abundance of its wastes within the country. The plantation would be seen to increase to at least 5.2 million ha by 2020, and the waste generation would be 50-70 times the plantation. However, the efficiency of bulk density is reduced. This is one of the main reasons of the initiation of this size reduction/ grinding research. With appropriate parameters, grinding will be seen to be helping in enhancing the inter-particle bindings, subsequently increasing the quality of final products. This paper focuses on the grinding quality involving palm oil wastes by using the Scanning Electron Microscope (SEM). The samples would first be ground to powder at varying grinding speed and finally got the randomly chosen particles measured to obtain the size range. The grinding speed was manipulated from 15 Hz to 40 Hz. From the data obtained, it was found the particles fineness increased with increasing grinding speed. In general, the size ranged from 45 μm to about 600 μm, where the finest was recorded at the speed of 40 Hz. It was also found that the binding was not so encouraging at very low speeds. Therefore, the optimum grinding speed for oil palm residues lied in the range of 25 Hz to 30 Hz. However, there were still limitations to be overcome if the accuracy of the image clarity is to be enhanced.

Bearing restoration by grinding

Science.gov (United States)

Hanau, H.; Parker, R. J.; Zaretsky, E. V.; Chen, S. M.; Bull, H. L.

1976-01-01

A joint program was undertaken by the NASA Lewis Research Center and the Army Aviation Systems Command to restore by grinding those rolling-element bearings which are currently being discarded at aircraft engine and transmission overhaul. Three bearing types were selected from the UH-1 helicopter engine (T-53) and transmission for the pilot program. No bearing failures occurred related to the restoration by grinding process. The risk and cost of a bearing restoration by grinding programs was analyzed. A microeconomic impact analysis was performed.

Steel grinding media in production use

International Nuclear Information System (INIS)

Nass, D.E.

1975-01-01

This paper reviews the types of steel being used for grinding rods and balls by the mining industry in U. S. and Canada. Results of a Dec. 1973 grinding media survey of U. S. and Canadian mills are summarized. Common alloying elements (C, Mn, Cr, Mo, Cu, etc.) are discussed. Grinding balls and rods are discussed separately; wear tests using irradiated balls are described. Finally, defects in grinding media are discussed

Multifunctional centrifugal grinding unit

Science.gov (United States)

Sevostyanov, V. S.; Uralskij, V. I.; Uralskij, A. V.; Sinitsa, E. V.

2018-03-01

The article presents scientific and engineering developments of multifunctional centrifugal grinding unit in which the selective effect of grinding bodies on the crushing material is realized, depending on its physical and mechanical characteristics and various schemes for organizing the technological process

Effect of Grinding and Resintering on the Fatigue Limit and Surface Characterization of a Y-TZP Ceramic.

Science.gov (United States)

Polli, Gabriela Scatimburgo; Hatanaka, Gabriel Rodrigues; Abi-Rached, Filipe de Oliveira; Pinelli, Lígia Antunes Pereira; Góes, Márcio de Sousa; Cesar, Paulo Francisco; Reis, José Maurício Dos Santos Nunes

2016-01-01

This study evaluated the effect of grinding protocols and resintering on flexural fatigue limit and surface characterization of LavaTM Y-TZP. Bar-shaped specimens (20×4.0×1.2 mm, n=40; 20×4.0×1.5 mm, n=80) were obtained. Half of the thinner specimens (1.2 mm) constituted the as-sintered group (AS), while the thicker ones (1.5 mm) were ground with diamond burs under irrigation (WG) or not (G). The other half of thinner and half of ground specimens were resintered (1000 ºC, 30 min), forming the groups ASR, WGR and GR. Fatigue limit (500,000 cycles, 10 Hz) was evaluated by staircase method in a 4-point flexural fixture. Data were analyzed by 2-way ANOVA and Tukey's test (α=0.05). Surface topography (n=3) and fracture area (n=3) were evaluated by SEM. X-ray diffraction data (n=1) was analyzed by Rietveld refinement. ANOVA revealed significant differences (pgrinding protocol, resintering and their interaction. Grinding increased the fatigue limit of non-resintered groups. There was no significant difference among the resintered groups. Resintering significantly increased the fatigue limit of the AS group only. Both protocols created evident grooves on zirconia surface. The failures initiated at the tensile side of all specimens. The percentages (wt%) of monoclinic phase were AS (8.6), ASR (1.2), G (1.8), GR (0.0), WG (8.2), WGR (0.0) before, and AS (7.4), ASR (6.5), G (3.2), GR (0.2), WG (4.6), WGR (1.1) after cyclic loading. Grinding increased the fatigue limit of non-resintered Y-TZP and formed evident grooves on its surface. Resintering provided significant increase in the fatigue limit of as-sintered specimens. In general, grinding and resintering decreased or zeroed the monoclinic phase.

A study of grinding characteristic of ferrule

International Nuclear Information System (INIS)

Lee, S. W.; Choi, H. Z.; Choi, Y. J.; Ahn, G. J.

2003-01-01

As recently optical communication industry is developed, request of optical communication part is increased. Ferrule is very important part which determines transmission efficiency and quality of information in the optical communication part. Most of ferrule processes are grinding which request high processing precision. Particularly, concentricity and cylindricity of inner and outer diameter is very important. The co-axle grinding process of ferrule is to make its concentricity all of uniform before centerless grinding. Surface integrity of ferrule is affected by kind of grinding wheels, grinding conditions, and characteristic of workpiece and equipment. In this study, surface integrity of workpiece according to change of grinding wheel speed, feed rate, regulating wheel speed and grinding force is investigate to improve the concentricity and roundness of ferrule from many experiments

Grinding Inside A Toroidal Cavity

Science.gov (United States)

Mayer, Walter; Adams, James F.; Burley, Richard K.

1987-01-01

Weld lines ground smooth within about 0.001 in. Grinding tool for smoothing longitudinal weld lines inside toroidal cavity includes curved tunnel jig to guide grinding "mouse" along weld line. Curvature of tunnel jig matched to shape of toroid so grinding ball in mouse follows circular arc of correct radius as mouse is pushed along tunnel. Tool enables precise control of grindout shape, yet easy to use.

Experimental Setup for Diamond Grinding Using Electrochemical InProcess Controlled Dressing (ECD of Grinding Wheel

Directory of Open Access Journals (Sweden)

M. A. Shavva

2014-01-01

Full Text Available The most effective method for finish machining of hard-metals and alloys is to use the diamond grinding wheels for grinding. An application of diamond wheels significantly increases the employee output, reduces costs, and raises manufacturing efficiency with achieving the high performance properties of treated surfaces.During grinding a working surface of diamond wheel wears out. It adversely affects the cutting capability of the diamond grains, and depending on the grinding conditions can occur through different mechanisms. Wear of diamond wheel causes distortion of its shape and reduces cutting properties. However, dressing of diamond wheels is a complicated and time-consuming operation in terms of manufacturing technique.Methods to make dressing of diamond grinding wheel have different types of classification. Classification of dressing methods by the type of energy used is as follows: mechanical, chemical, electrophysical, electromechanical, and electrochemical. All these methods have their advantages and disadvantages.Electrochemical method of dressing is the most productive and efficient. Electrochemical method comprises anode-mechanical dressing and electrochemical (electrolytic one. The paper presents the electrochemical in-process dressing (ECD and the electrolytic in-process dressing (ELID.The source of energy, grinding a wheel with metal bond, and an electrode are necessary for providing ELID. The ELID consists of several stages. The first stage is preliminary electrolytic dressing of diamond wheel. The electrolyte is placed into the gap between the wheel and electrode. The bond of the wheel is oxidized. An insulating layer is formed. It reduces an electrical conductivity of the wheel and controls consumption of diamond grains, as well as polishes the surface of the work piece. Further, the insulating layer is destroyed. The cycle of dressing begins anew.The ECD proceeds in the same way as ELID. However during the ECD-process there

Characterisation and management of concrete grinding residuals.

Science.gov (United States)

Kluge, Matt; Gupta, Nautasha; Watts, Ben; Chadik, Paul A; Ferraro, Christopher; Townsend, Timothy G

2018-02-01

Concrete grinding residue is the waste product resulting from the grinding, cutting, and resurfacing of concrete pavement. Potential beneficial applications for concrete grinding residue include use as a soil amendment and as a construction material, including as an additive to Portland cement concrete. Concrete grinding residue exhibits a high pH, and though not hazardous, it is sufficiently elevated that precautions need to be taken around aquatic ecosystems. Best management practices and state regulations focus on reducing the impact on such aquatic environment. Heavy metals are present in concrete grinding residue, but concentrations are of the same magnitude as typically recycled concrete residuals. The chemical composition of concrete grinding residue makes it a useful product for some soil amendment purposes at appropriate land application rates. The presence of unreacted concrete in concrete grinding residue was examined for potential use as partial replacement of cement in new concrete. Testing of Florida concrete grinding residue revealed no dramatic reactivity or improvement in mortar strength.

AUTOMATION OF IN FEED CENTERLESS GRINDING MACHINE

OpenAIRE

Piyusha P. Jadhav*, Sachin V. Lomte, Sudhir Surve

2017-01-01

In-feed centerless grinding technique offers a major contribution to the industries. This is the alternative in-feed centerless grinding technique using regulating wheel. Mainly centerless grinding is divided in three types, and those are End feed, in-feed and through feed Centerless grinding. This paper mainly deals with low cost automation on in-feed Centerless grinding machine using regulating wheel suitable for multiple in-feed type jobs. It deals with the development of a Centerless grin...

Influence of different surface treatments on the fracture toughness of a commercial ZTA dental ceramic

Directory of Open Access Journals (Sweden)

Flavio Teixeira da Silva

2007-03-01

Full Text Available The objective of this study was to investigate how mechanical surface treatments performed for removal of excess of molten glass, influence the fracture toughness of a dental zirconia toughened alumina (In-Ceram® Zirconia. Infiltrated ZTA disks were submitted to three different surface treatments (grinding, sandblasting and grinding + sandblasting + annealing. Fracture toughness was accessed through indentation strength test (IS. X ray diffraction was used to investigate the metastability of tetragonal zirconia particles under all treatments proposed. Kruskall-Wallis non-parametrical test and Weibull statistics were used to analyze the results. Grinding (group 1 introduced defects which decreased the fracture toughness and reliability, presenting the lowest K IC. On the other hand, grinding followed by sandblasting and annealing (group 3 presented the highest K IC. Sandblasting (group 2 presented the highest reliability but lower K IC compared to group 3.

Nuclear fusion project. Semi-annual report of the Association KfK/EURATOM

International Nuclear Information System (INIS)

Kast, G.

1987-05-01

This semi-annual report gives 36 short descriptions of the work done in the framework of the Nuclear Fusion Project and outlines studies for NET/INTOR and for ECRH power sources at 150 GHz. Tables of fusion technology contracts, of NET contracts, of KfK departments contributing to the Fusion Project, and of the Fusion Project management staff complete this report. (GG)

Grinding temperature and energy ratio coefficient in MQL grinding of high-temperature nickel-base alloy by using different vegetable oils as base oil

Directory of Open Access Journals (Sweden)

Li Benkai

2016-08-01

Full Text Available Vegetable oil can be used as a base oil in minimal quantity of lubrication (MQL. This study compared the performances of MQL grinding by using castor oil, soybean oil, rapeseed oil, corn oil, sunflower oil, peanut oil, and palm oil as base oils. A K-P36 numerical-control precision surface grinder was used to perform plain grinding on a workpiece material with a high-temperature nickel base alloy. A YDM–III 99 three-dimensional dynamometer was used to measure grinding force, and a clip-type thermocouple was used to determine grinding temperature. The grinding force, grinding temperature, and energy ratio coefficient of MQL grinding were compared among the seven vegetable oil types. Results revealed that (1 castor oil-based MQL grinding yields the lowest grinding force but exhibits the highest grinding temperature and energy ratio coefficient; (2 palm oil-based MQL grinding generates the second lowest grinding force but shows the lowest grinding temperature and energy ratio coefficient; (3 MQL grinding based on the five other vegetable oils produces similar grinding forces, grinding temperatures, and energy ratio coefficients, with values ranging between those of castor oil and palm oil; (4 viscosity significantly influences grinding force and grinding temperature to a greater extent than fatty acid varieties and contents in vegetable oils; (5 although more viscous vegetable oil exhibits greater lubrication and significantly lower grinding force than less viscous vegetable oil, high viscosity reduces the heat exchange capability of vegetable oil and thus yields a high grinding temperature; (6 saturated fatty acid is a more efficient lubricant than unsaturated fatty acid; and (7 a short carbon chain transfers heat more effectively than a long carbon chain. Palm oil is the optimum base oil of MQL grinding, and this base oil yields 26.98 N tangential grinding force, 87.10 N normal grinding force, 119.6 °C grinding temperature, and 42.7% energy

76 FR 45862 - Agency Information Collection Activities: New Collection; Semi-Annual Progress Report for...

Science.gov (United States)

2011-08-01

... the Services, Training, Education and Policies to Reduce Domestic Violence, Dating Violence, Sexual... Collection; Semi- Annual Progress Report for Grantees From the Services, Training, Education and Policies To Reduce Domestic Violence, Dating Violence, Sexual Assault and Stalking in Secondary Schools Grant Program...

Manufacturing conditioned roughness and wear of biomedical oxide ceramics for all-ceramic knee implants.

Science.gov (United States)

Turger, Anke; Köhler, Jens; Denkena, Berend; Correa, Tomas A; Becher, Christoph; Hurschler, Christof

2013-08-29

Ceramic materials are used in a growing proportion of hip joint prostheses due to their wear resistance and biocompatibility properties. However, ceramics have not been applied successfully in total knee joint endoprostheses to date. One reason for this is that with strict surface quality requirements, there are significant challenges with regard to machining. High-toughness bioceramics can only be machined by grinding and polishing processes. The aim of this study was to develop an automated process chain for the manufacturing of an all-ceramic knee implant. A five-axis machining process was developed for all-ceramic implant components. These components were used in an investigation of the influence of surface conformity on wear behavior under simplified knee joint motion. The implant components showed considerably reduced wear compared to conventional material combinations. Contact area resulting from a variety of component surface shapes, with a variety of levels of surface conformity, greatly influenced wear rate. It is possible to realize an all-ceramic knee endoprosthesis device, with a precise and affordable manufacturing process. The shape accuracy of the component surfaces, as specified by the design and achieved during the manufacturing process, has a substantial influence on the wear behavior of the prosthesis. This result, if corroborated by results with a greater sample size, is likely to influence the design parameters of such devices.

Study on Effect of Ultrasonic Vibration on Grinding Force and Surface Quality in Ultrasonic Assisted Micro End Grinding of Silica Glass

Directory of Open Access Journals (Sweden)

Zhang Jianhua

2014-01-01

Full Text Available Ultrasonic vibration assisted micro end grinding (UAMEG is a promising processing method for micro parts made of hard and brittle materials. First, the influence of ultrasonic assistance on the mechanism of this processing technology is theoretically analyzed. Then, in order to reveal the effects of ultrasonic vibration and grinding parameters on grinding forces and surface quality, contrast grinding tests of silica glass with and without ultrasonic assistance using micro radial electroplated diamond wheel are conducted. The grinding forces are measured using a three-component dynamometer. The surface characteristics are detected using the scanning electron microscope. The experiment results demonstrate that grinding forces are significantly reduced by introducing ultrasonic vibration into conventional micro end grinding (CMEG of silica glass; ultrasonic assistance causes inhibiting effect on variation percentages of tangential grinding force with grinding parameters; ductile machining is easier to be achieved and surface quality is obviously improved due to ultrasonic assistance in UAMEG. Therefore, larger grinding depth and feed rate adopted in UAMEG can lead to the improvement of removal rate and machining efficiency compared with CMEG.

Nitramine Drying & Fine Grinding Facility

Data.gov (United States)

Federal Laboratory Consortium — The Nitramine Drying and Fine Grinding Facility provides TACOM-ARDEC with a state-of-the-art facility capable of drying and grinding high explosives (e.g., RDX and...

Rotating Beam Fatigue Testing and Hybrid Ceramic Bearings.

Science.gov (United States)

1994-07-01

Runout and Fast Fracture ......... 20 FIG.7 Stress-life Plots of Rotating Beam Fatigue Testing ............. 23 FIG.8 Fractograph of Rotating Beam...Chand-Kare Engineering Ceramics, Worcester, MA. Diamond wheels of 600 grits were used with longitudinal grinding applied for the final finishing of...stress in the range of 600-850 MPa. Three test completion modes were encountered, i.e. fast fracture at setup, fatigue fracture and runout (no failure

For production of ceramic plates coating using waste kaolin, granite and marble

International Nuclear Information System (INIS)

Sales, J.L.; Morais, C.R.S.; Lima, L.M.R.; Altidis, M.E.D.

2011-01-01

The objective is to benefit and characterize waste from kaolin, marble and granite studying their thermal properties and spectroscopic in employment perspective on ceramic production of flooring boards. The residues were benefited through the process of dry grinding mill in greyhounds and passed through sieve 0.074 mm (ABNT No. 200), observing their suitability for the formulation of ceramic pastes. Tests were performed physicochemical characterization (particle size analysis, X-ray fluorescence and X-ray diffraction) and thermal (differential thermal analysis and thermogravimetry). The results showed that these residues showed satisfactory properties for the purpose for which it proposes, and contribute to reducing environmental impacts, allowing the reuse of the production of ceramic plates (author)

Grinding arrangement for ball nose milling cutters

Science.gov (United States)

Burch, C. F. (Inventor)

1974-01-01

A grinding arrangement for spiral fluted ball nose end mills and like tools includes a tool holder for positioning the tool relative to a grinding wheel. The tool is mounted in a spindle within the tool holder for rotation about its centerline and the tool holder is pivotably mounted for angular movement about an axis which intersects that centerline. A follower arm of a cam follower secured to the spindle cooperates with a specially shaped cam to provide rotation of the tool during the angular movement of the tool holder during the grinding cycle, by an amount determined by the cam profile. In this way the surface of the cutting edge in contact with the grinding wheel is maintained at the same height on the grinding wheel throughout the angular movement of the tool holder during the grinding cycle.

Control of grinding polygonal surfaces

Directory of Open Access Journals (Sweden)

Юрій Володимирович Петраков

2017-12-01

Full Text Available Grinding of non-round surfaces, in particular polygonal surfaces of dies, is characterized by substantial non stationary. At different sections of the profile, the change in the main characteristic (Material Removal Rate – MRR process reaches tens of times. To stabilize the grinding process, it is recommended to control the spindle speed of the workpiece CNC grinding machine. Created software that allows to design the control program on the basis of mathematical model of the system. The determination of MRR is realized automatically in the simulation of the grinding process which uses the algorithm developed for solving problems in geometric interaction of the workpiece and the wheel. In forming the control program is possible takes into account the limitations on the maximum circumferential force of cutting, and the maximum allowable acceleration of the machine spindle. Practice has shown that full stabilization is not obtained, even though the performance is increased more than 2 times, while ensuring the quality of the surface. The developed block diagram of the grinding process can serve as a basis for further improvement in the solution of dynamic problems.

Energy requirement for fine grinding of torrefied wood

Energy Technology Data Exchange (ETDEWEB)

Repellin, Vincent; Govin, Alexandre; Guyonnet, Rene [Department of Powder and Multi-Components Materials (PMMC), SPIN Research Center, Ecole des Mines de Saint Etienne (EMSE), 158 Cours Fauriel, F-42023 Saint-Etienne (France); Rolland, Matthieu [Process Developments and Engineering Division, Chemical Engineering Department, Institut Francais du Petrole (IFP-Lyon), F-69390 Vernaison (France)

2010-07-15

The purpose of this study is to investigate the influence of torrefaction on wood grinding energy. Wood chips were torrefied at different temperatures and durations. The energy required to obtain fine powder was measured. Particle size analyses were carried out on each powder sample. It is showed that torrefaction decreases both grinding energy and particle size distribution. A criterion to compare grindability of natural and torrefied wood is proposed. It takes into account both grinding energy and particle size distribution. It accounts the energy required for grinding particles to sizes inferior to 200 {mu}m, for given grinding conditions. Torrefaction is characterised by the anhydrous weight loss (AWL) of wood. For AWL inferior to around 8%, grinding energy decreases fast. Over 8%, grinding energy decreases at a slow rate. Particle size distribution decreases linearly as the AWL increases. Both for spruce and beech, the grinding criterion is decreased of 93% when the AWL is around 28%. (author)

Investigation and characterization of densification, processing and mechanical properties of TiB2–SiC ceramics

International Nuclear Information System (INIS)

Chen, Hongbo; Wang, Zhi; Wu, Zhanjun

2014-01-01

Highlights: • This paper is first to use induction heating to densify TiB 2 –SiC ceramic. • The grinding parameters on microstructure and flexural strength were investigated. • The residual stress was measured using X-ray diffraction. • The high-frequency induction heating has more advantages over hot-pressing. - Abstract: In the present work, high-frequency induction heating was firstly used to densify TiB 2 –SiC ceramic, and the microstructure analysis indicated that the average grain size of the sample, which was sintered through induction heating, was smaller than that of the sample sintered through hot-pressing. The flexural strength and fracture toughness were improved after refining the grains and increasing the relative density. In order to characterize the densification behavior of TiB 2 –SiC ceramic sintered through induction heating, the typical curve of measured linear shrinkage of a sample was calculated and used. The tangential and normal grinding forces were substituted by the horizontal and vertical forces measured from the dynamometer in order to characterize intuitively the effect of grinding parameters on the microstructure and residual stress. The above-mentioned results revealed that the high-frequency induction heating has more advantages over hot-pressing. The results and way of these works can be applied to aid materials engineering design for the development of new materials, quality assurance, and characterization assessment of durability

Zirconia changes after grinding and regeneration firing.

Science.gov (United States)

Hatanaka, Gabriel R; Polli, Gabriela S; Fais, Laiza M G; Reis, José Maurício Dos S N; Pinelli, Lígia A P

2017-07-01

Despite improvements in computer-aided design and computer-aided manufacturing (CAD-CAM) systems, grinding during either laboratory procedures or clinical adjustments is often needed to modify the shape of 3 mol(%) yttria-tetragonal zirconia polycrystal (3Y-TZP) restorations. However, the best way to achieve adjustment is unclear. The purpose of this in vitro study was to evaluate the microstructural and crystallographic phase changes, flexural strength, and Weibull modulus of a 3Y-TZP zirconia after grinding with or without water cooling and regeneration firing. Ninety-six bar-shaped specimens were obtained and divided as follows: as-sintered, control; as-sintered with regeneration firing; grinding without water cooling; grinding and regeneration firing with water cooling; and grinding and regeneration firing. Grinding (0.3 mm) was performed with a 150-μm diamond rotary instrument in a high-speed handpiece. For regeneration firing, the specimens were annealed at 1000°C for 30 minutes. The crystalline phases were evaluated by using x-ray powder diffraction. A 4-point bending test was conducted (10 kN; 0.5 mm/min). The Weibull modulus was used to analyze strength reliability. The microstructure was analyzed by scanning electron microscopy. Data from the flexural strength test were evaluated using the Kruskal-Wallis and Dunn tests (α=.05). Tetragonal-to-monoclinic phase transformation was identified in the ground specimens; R regeneration firing groups showed only the tetragonal phase. The median flexural strength of as-sintered specimens was 642.0; 699.3 MPa for as-sintered specimens with regeneration firing; 770.1 MPa for grinding and water-cooled specimens; 727.3 MPa for specimens produced using water-cooled grinding and regeneration firing; 859.9 MPa for those produced by grinding; and 764.6 for those produced by grinding and regeneration firing; with statistically higher values for the ground groups. The regenerative firing did not affect the flexural

76 FR 30388 - Agency Information Collection Activities: New collection Semi-Annual Progress Report for Grantees...

Science.gov (United States)

2011-05-25

... Grantees from the Services, Training, Education and Policies to Reduce Domestic Violence, Dating Violence... collection Semi- Annual Progress Report for Grantees From the Services, Training, Education and Policies To Reduce Domestic Violence, Dating Violence, Sexual Assault and Stalking in Secondary Schools Grant Program...

Translucency of dental ceramics with different thicknesses.

Science.gov (United States)

Wang, Fu; Takahashi, Hidekazu; Iwasaki, Naohiko

2013-07-01

The increased use of esthetic restorations requires an improved understanding of the translucent characteristics of ceramic materials. Ceramic translucency has been considered to be dependent on composition and thickness, but less information is available about the translucent characteristics of these materials, especially at different thicknesses. The purpose of this study was to investigate the relationship between translucency and the thickness of different dental ceramics. Six disk-shaped specimens of 8 glass ceramics (IPS e.max Press HO, MO, LT, HT, IPS e.max CAD LT, MO, AvanteZ Dentin, and Trans) and 5 specimens of 5 zirconia ceramics (Cercon Base, Zenotec Zr Bridge, Lava Standard, Lava Standard FS3, and Lava Plus High Translucency) were prepared following the manufacturers' instructions and ground to a predetermined thickness with a grinding machine. A spectrophotometer was used to measure the translucency parameters (TP) of the glass ceramics, which ranged from 2.0 to 0.6 mm, and of the zirconia ceramics, which ranged from 1.0 to 0.4 mm. The relationship between the thickness and TP of each material was evaluated using a regression analysis (α=.05). The TP values of the glass ceramics ranged from 2.2 to 25.3 and the zirconia ceramics from 5.5 to 15.1. There was an increase in the TP with a decrease in thickness, but the amount of change was material dependent. An exponential relationship with statistical significance (Pceramics and zirconia ceramics. The translucency of dental ceramics was significantly influenced by both material and thickness. The translucency of all materials increased exponentially as the thickness decreased. All of the zirconia ceramics evaluated in the present study showed some degree of translucency, which was less sensitive to thickness compared to that of the glass ceramics. Copyright © 2013 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

Grinding temperature and energy ratio coe cient in MQL grinding of high-temperature nickel-base alloy by using di erent vegetable oils as base oil

Institute of Scientific and Technical Information of China (English)

Li Benkai; Li Changhe; Zhang Yanbin; Wang Yaogang; Jia Dongzhou; Yang Min

2016-01-01

Vegetable oil can be used as a base oil in minimal quantity of lubrication (MQL). This study compared the performances of MQL grinding by using castor oil, soybean oil, rapeseed oil, corn oil, sunflower oil, peanut oil, and palm oil as base oils. A K-P36 numerical-control precision surface grinder was used to perform plain grinding on a workpiece material with a high-temperature nickel base alloy. A YDM–III 99 three-dimensional dynamometer was used to measure grinding force, and a clip-type thermocouple was used to determine grinding temperature. The grinding force, grind-ing temperature, and energy ratio coefficient of MQL grinding were compared among the seven veg-etable oil types. Results revealed that (1) castor oil-based MQL grinding yields the lowest grinding force but exhibits the highest grinding temperature and energy ratio coefficient;(2) palm oil-based MQL grinding generates the second lowest grinding force but shows the lowest grinding temperature and energy ratio coefficient;(3) MQL grinding based on the five other vegetable oils produces similar grinding forces, grinding temperatures, and energy ratio coefficients, with values ranging between those of castor oil and palm oil;(4) viscosity significantly influences grinding force and grinding tem-perature to a greater extent than fatty acid varieties and contents in vegetable oils;(5) although more viscous vegetable oil exhibits greater lubrication and significantly lower grinding force than less vis-cous vegetable oil, high viscosity reduces the heat exchange capability of vegetable oil and thus yields a high grinding temperature;(6) saturated fatty acid is a more efficient lubricant than unsaturated fatty acid;and (7) a short carbon chain transfers heat more effectively than a long carbon chain. Palm oil is the optimum base oil of MQL grinding, and this base oil yields 26.98 N tangential grinding force, 87.10 N normal grinding force, 119.6 °C grinding temperature, and 42.7%energy ratio coefficient

Automatic grinding apparatus to control uniform specimen thicknesses

Science.gov (United States)

Bryner, Joseph S.

1982-01-01

This invention is directed to a new and improved grinding apparatus comprising (1) a movable grinding surface, (2) a specimen holder, (3) a displacing device for moving the holder and/or grinding surface toward one another, and (4) at least three devices for limiting displacement of the holder to the grinding surface.

The grinding of uranium dioxide from fluidized beds

International Nuclear Information System (INIS)

Alonso Folgueras, J. A.

1974-01-01

This work deals with the UO 2 vibratory grinding, the UO 2 obtained from fluidized beds. In this study the grinding time has been correlated with surface area, stoichiometry, granulometry and grinded product contamination. The efficiency losses in the grinding of moisten UO 2 are outlined. Finally it is made a brief study of the granulate obtained from the grinded UO 2 as well as the green pellets resulting from it, taking into consideration the dispersion of its density and height. (Author)

30 CFR 57.14115 - Stationary grinding machines.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Stationary grinding machines. 57.14115 Section... and Equipment Safety Devices and Maintenance Requirements § 57.14115 Stationary grinding machines. Stationary grinding machines, other than special bit grinders, shall be equipped with— (a) Peripheral hoods...

Numerical Simulation of a Grinding Process for the Spatial Work-pieces: a Model of the Workpiece and Grinding Wheel

Directory of Open Access Journals (Sweden)

I. A. Kiselev

2015-01-01

Full Text Available The paper describes a spatial grinding dynamics mathematical model. This model includes a grinding wheel dynamics model, a work-piece dynamics model, and a numerical algorithm of geometric modeling as well. The geometric modeling algorithm is based on the Z-buffer method with author’s modifications. This algorithm allows us to simulate the formation of a new workpiece surface when removing material and as well as to determine the cutting layer thickness for each abrasive grain of the grinding wheel. The use of the surface cell bilinear approximation and the simultaneous use of multiple projection directions are the special features of the algorithm. These features improve modeling quality of machined surface. The grinding wheel model is represented as cutting micro-edges (grains set. Abrasive grains are randomly distributed on the wheel outer surface. Grains size, shape, wheel structure and graininess are taken into account. To determine the uncut chip thickness, which is cut off by each grain of the grinding wheel is used the algorithm, which finds intersection point of uncut work-piece surface with radial ray passing through the grain cutting edge. Grinding forces for each grain are defined based on the cutting layer thickness value using the phenomenological models described in the literature. Using transformations described in the article, grinding forces determined for each grain are reduced to the total grinding force, which acts on the tool and machined work-piece in the appropriate coordinate systems. Work-piece dynamics is modeled with the help of the finite element method using quadratic tetrahedral elements. The described model of spatial grinding dynamics makes it possible to evaluate the level of vibration and grinding forces, as well as the shape errors and surface quality of machined work-piece.

30 CFR 56.14115 - Stationary grinding machines.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Stationary grinding machines. 56.14115 Section... Equipment Safety Devices and Maintenance Requirements § 56.14115 Stationary grinding machines. Stationary grinding machines, other than special bit grinders, shall be equipped with— (a) Peripheral hoods capable of...

Mechanical properties of silicon in subsurface damage layer from nano-grinding studied by atomistic simulation

Science.gov (United States)

Zhang, Zhiwei; Chen, Pei; Qin, Fei; An, Tong; Yu, Huiping

2018-05-01

Ultra-thin silicon wafer is highly demanded by semi-conductor industry. During wafer thinning process, the grinding technology will inevitably induce damage to the surface and subsurface of silicon wafer. To understand the mechanism of subsurface damage (SSD) layer formation and mechanical properties of SSD layer, atomistic simulation is the effective tool to perform the study, since the SSD layer is in the scale of nanometer and hardly to be separated from underneath undamaged silicon. This paper is devoted to understand the formation of SSD layer, and the difference between mechanical properties of damaged silicon in SSD layer and ideal silicon. With the atomistic model, the nano-grinding process could be performed between a silicon workpiece and diamond tool under different grinding speed. To reach a thinnest SSD layer, nano-grinding speed will be optimized in the range of 50-400 m/s. Mechanical properties of six damaged silicon workpieces with different depths of cut will be studied. The SSD layer from each workpiece will be isolated, and a quasi-static tensile test is simulated to perform on the isolated SSD layer. The obtained stress-strain curve is an illustration of overall mechanical properties of SSD layer. By comparing the stress-strain curves of damaged silicon and ideal silicon, a degradation of Young's modulus, ultimate tensile strength (UTS), and strain at fracture is observed.

Mechanical properties of silicon in subsurface damage layer from nano-grinding studied by atomistic simulation

Directory of Open Access Journals (Sweden)

Zhiwei Zhang

2018-05-01

Full Text Available Ultra-thin silicon wafer is highly demanded by semi-conductor industry. During wafer thinning process, the grinding technology will inevitably induce damage to the surface and subsurface of silicon wafer. To understand the mechanism of subsurface damage (SSD layer formation and mechanical properties of SSD layer, atomistic simulation is the effective tool to perform the study, since the SSD layer is in the scale of nanometer and hardly to be separated from underneath undamaged silicon. This paper is devoted to understand the formation of SSD layer, and the difference between mechanical properties of damaged silicon in SSD layer and ideal silicon. With the atomistic model, the nano-grinding process could be performed between a silicon workpiece and diamond tool under different grinding speed. To reach a thinnest SSD layer, nano-grinding speed will be optimized in the range of 50-400 m/s. Mechanical properties of six damaged silicon workpieces with different depths of cut will be studied. The SSD layer from each workpiece will be isolated, and a quasi-static tensile test is simulated to perform on the isolated SSD layer. The obtained stress-strain curve is an illustration of overall mechanical properties of SSD layer. By comparing the stress-strain curves of damaged silicon and ideal silicon, a degradation of Young’s modulus, ultimate tensile strength (UTS, and strain at fracture is observed.

THE MECHANOCHEMICAL SYNTHESIS OF NEW FIREPROOF CERAMIC MATERIALS WITH THE USE OF SECOND MINERAL RESOURSES

Directory of Open Access Journals (Sweden)

M. V. Lukhanin

2016-04-01

Full Text Available Possibility of receipt from the natural resources of Kuzbas and wastes of industry by means of mechanochemical method of grind of the mixtures, new mullite-kordierite kompozits, suitable for the production of wide line of fireproof and ceramic products is set in the work.

Simulation of the infiltration process of a ceramic open-pore body with a metal alloy in semi-solid state to design the manufacturing of interpenetrating phase composites

Science.gov (United States)

Schomer, Laura; Liewald, Mathias; Riedmüller, Kim Rouven

2018-05-01

Metal-ceramic Interpenetrating Phase Composites (IPC) belong to a special subcategory of composite materials and reveal enhanced properties compared to conventional composite materials. Currently, IPC are produced by infiltration of a ceramic open-pore body with liquid metal applying high pressure and I or high temperature to avoid residual porosity. However, these IPC are not able to gain their complete potential, because of structural damages and interface reactions occurring during the manufacturing process. Compared to this, the manufacturing of IPC using the semi-solid forming technology offers great perspectives due to relative low processing temperatures and reduced mechanical pressure. In this context, this paper is focusing on numerical investigations conducted by using the FLOW-3D software for gaining a deeper understanding of the infiltration of open-pore bodies with semi-solid materials. For flow simulation analysis, a geometric model and different porous media drag models have been used. They have been adjusted and compared to get a precise description of the infiltration process. Based on these fundamental numerical investigations, this paper also shows numerical investigations that were used for basically designing a semi-solid forming tool. Thereby, the development of the flow front and the pressure during the infiltration represent the basis of the evaluation. The use of an open and closed tool cavity combined with various geometries of the upper die shows different results relating to these evaluation arguments. Furthermore, different overflows were designed and its effects on the pressure at the end of the infiltration process were investigated. Thus, this paper provides a general guideline for a tool design for manufacturing of metal-ceramic IPC using semi-solid forming.

30 CFR 75.1723 - Stationary grinding machines; protective devices.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Stationary grinding machines; protective....1723 Stationary grinding machines; protective devices. (a) Stationary grinding machines other than... the wheel. (3) Safety washers. (b) Grinding wheels shall be operated within the specifications of the...

Experimental Investigation on the Performance of Grinding Assisted Electrochemical Discharge Drilling of Glass

Directory of Open Access Journals (Sweden)

Ladeesh V G

2016-01-01

Full Text Available Grinding assisted electrochemical discharge drilling (G-ECDD is a novel technique for producing micro and macro holes in brittle materials including advanced ceramics and glass, both efficiently and economically. G-ECDD involves the use of a rotating diamond core drill as the tool in a normal electrochemical discharge machine setup. The material removal happens by a combination of thermal melting due to electric discharges, followed by grinding action of diamond grits and chemical etching action. In this study, the effect of process parameters like voltage, duty cycle, cycle time and electrolyte concentration on material removed (MR was investigated systematically using response surface methodology. Analysis of variance was performed to identify the significant factors and their percentage contribution. The most significant factor was found to be duty cycle followed by voltage, cycle time and concentration. A quadratic mathematical model was developed to predict MR. Tool wear was found for different frequencies and voltages. Higher tool wear was observed for high frequency above 5kHz pulsed DC supply at high voltage of 110V. Tool wear at the end face of the tool was found to be a significant problem affecting the tool life.

17 CFR 270.30b1-1 - Semi-annual report for registered management investment companies.

Science.gov (United States)

2010-04-01

... registered management investment companies. 270.30b1-1 Section 270.30b1-1 Commodity and Securities Exchanges....30b1-1 Semi-annual report for registered management investment companies. Every registered management... management investment company that has filed a registration statement with the Commission registering its...

Preparation and properties of bisphenol-F based boron-phenolic resin/modified silicon nitride composites and their usage as binders for grinding wheels

International Nuclear Information System (INIS)

Lin, Chun-Te; Lee, Hsun-Tsing; Chen, Jem-Kun

2015-01-01

Highlights: • Bisphenol-F based boron-phenolic resins (B-BPF) with B−O bonds were synthesized. • The modified silicon nitride (m-SiN) was well dispersed and adhered in the B-BPF. • B-BPF/m-SiN composites have good thermal resistance and mechanical properties. • The grinding wheels bound by B-BPF/m-SiN have excellent grinding quality. - Abstract: In this study, phenolic resins based on bisphenol-F (BPF) were synthesized. Besides, ammonium borate was added in the synthesis process of BPF to form the bisphenol-F based boron-phenolic resins (B-BPF). The glass transition temperature, thermal resistance, flexural strength and hardness of B-BPF are respectively higher than those of BPF. This is due to the presence of new cross-link B−O bonds in the B-BPF. In addition, the 3-aminopropyltriethoxysilane modified silicon nitride powders (m-SiN) were fully mixed with B-BPF to form the B-BPF/m-SiN composites. The thermal resistance and mechanical properties of the B-BPF/m-SiN are promoted by the well-dispersed and well-adhered m-SiN in these novel polymer/ceramics composites. The results of grinding experiments indicate that the grinding wheels bound by the B-BPF/m-SiN have better grinding quality than those bound by the BPF. Thus the B-BPF/m-SiN composites are better binding media than the BPF resins

A Review of Literature on analysis of JIG Grinding Process

DEFF Research Database (Denmark)

Sudheesh, P. K.; Puthumana, Govindan

2016-01-01

Jig grinding is a process practically used by tool and die makers in the creation of jigs or mating holes and pegs on dies.The abrasives normally used in jig grinding are divided into Natural Abrasives and Artificial Abrasives. Artificial Abrasiveare preferred in manufacturing of grinding wheels...... in jig grinding, because of their uniformity and purity. In this paper, abrief review of the analysis of jig grinding process considering various research trends is presented. The areas highlighted are: optimization, selection of abrasives, selection of processing conditions and practical considerations....... The optimization of parameters in jig grinding process is important to maximize productivity and to improve quality. The abrasives of hard jig grinding wheels get blunt quickly so these are recommended to grind workpiece of low hardness and soft grinding wheels are recommended for hard material workpieces. The jig...

Spectroscopic Properties of Neodymium and Erbium-Doped Magnesium Oxide Ceramics

Science.gov (United States)

2015-09-01

universally >99% of theoretical. Powder x-ray diffraction (XRD) analysis was employed to determine the crystalline phases in doped MgO ceramics after the...different sintering steps. Powders of sintered pellets were prepared by grinding fragments in a glass mortar and pestle to avoid crystalline...than anticipated for the doped MgO. Somewhat more conclusive information on the extent of successful RE doping was derived from the XRD analysis

Elucidating Grinding Mechanism by Theoretical and Experimental Investigations.

Science.gov (United States)

Ullah, Amm Sharif; Caggiano, Alessandra; Kubo, Akihiko; Chowdhury, M A K

2018-02-09

Grinding is one of the essential manufacturing processes for producing brittle or hard materials-based precision parts (e.g., optical lenses). In grinding, a grinding wheel removes the desired amount of material by passing the same area on the workpiece surface multiple times. How the topography of a workpiece surface evolves with these passes is thus an important research issue, which has not yet been addressed elaborately. The present paper tackles this issue from both the theoretical and the experimental points of view. In particular, this paper presents the results of experimental and theoretical investigations on the multi-pass surface grinding operations where the workpiece surface is made of glass and the grinding wheel consists of cBN abrasive grains. Both investigations confirm that a great deal of stochasticity is involved in the grinding mechanism, and the complexity of the workpiece surface gradually increases along with the number of passes.

13 CFR 307.14 - Revolving Loan Fund semi-annual report and Income and Expense Statement.

Science.gov (United States)

2010-01-01

... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Revolving Loan Fund semi-annual report and Income and Expense Statement. 307.14 Section 307.14 Business Credit and Assistance ECONOMIC...) any modifications to the RLF Plan to ensure effective use of the RLF as a strategic financing tool. (c...

Progress in abrasive and grinding technology

CERN Document Server

Xu, Xipeng

2009-01-01

The grinding and abrasive processing of materials are machining techniques which use bonded or loose abrasives to remove material from workpieces. Due to the well-known advantages of grinding and abrasive processes, advances in abrasive and grinding technology are always of great import in enhancing both productivity and component quality. In order to highlight the recent progress made in this field, the editor invited 21 world-wide contributions with the aim of gathering together all of the achievements of leading researchers into a single publication. The authors of the 21 invited papers, of

Effect of coarse grinding, overglazing, and 2 polishing systems on the flexural strength, surface roughness, and phase transformation of yttrium-stabilized tetragonal zirconia.

Science.gov (United States)

Mohammadi-Bassir, Mahshid; Babasafari, Mansoure; Rezvani, Mohammad Bagher; Jamshidian, Mahdieh

2017-11-01

Limited information is available for the best polishing systems and methods to obtain minimally abrasive monolithic zirconia surfaces after contouring and occlusal adjustment. The purpose of this in vitro study was to evaluate the effect of grinding and polishing procedures on the flexural strength, quality and quantity of surface roughness, topography, and phase transformation of a zirconia-based ceramic system. Fifty bar-shaped yttrium-stabilized zirconium oxide specimens (20×4×2 mm) were cut from presintered zirconia blanks. The specimens were wet-polished and divided into 5 groups (n=10): standard polishing without any surface treatment (group SP); grinding with a diamond rotary instrument (group Gr); grinding with a diamond rotary instrument (DRI) and over-glazing (group Gl); grinding with a DRI and polishing with an intraoral zirconia polishing kit in a 2-step procedure (group BP); and grinding with a DRI and polishing with an intraoral polishing kit (group MP). The Ra and Rz surface roughness values (μm) were measured with a profilometer. One specimen of each group was subjected to x-ray diffraction (XRD) to estimate the monoclinic phase and evaluated using scanning electron microscopy (SEM) for surface topography. The 3-point flexural strength of the bars was measured in a universal testing machine at a crosshead speed of 0.5 mm/min. The mean flexural strength (MPa) and surface roughness values were calculated, and the results were analyzed using 1-way ANOVA and Tukey honest significant difference tests (α=.05). Statistically significant differences were noted among the experimental groups for Ra, Rz (Pgrinding that were smoothened by glazing and polishing. Roughness increased significantly after grinding, but polishing and glazing similarly diminished it. Glazing after grinding significantly decreased the flexural strength values, but polishing did not. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier

System Analysis of Flat Grinding Process with Wheel Face

Directory of Open Access Journals (Sweden)

T. N. Ivanova

2014-01-01

Full Text Available The paper presents a conducted system analysis of the flat grinding wheel face, considers the state parameters, input and output variables of subsystems, namely: machine tool, workpiece, grinding wheel, cutting fluids, and the contact area. It reveals the factors influencing the temperature and power conditions for the grinding process.Aim: conducting the system analysis of the flat grinding process with wheel face expects to enable a development of the system of grinding process parameters as a technical system, which will make it possible to evaluate each parameter individually and implement optimization of the entire system.One of the most important criteria in defining the optimal process conditions is the grinding temperature, which, to avoid defects appearance of on the surface of component, should not exceed the critical temperature values to be experimentally determined. The temperature criterion can be useful for choosing the conditions for the maximum defect-free performance of the mechanical face grinding. To define the maximum performance of defect-free grinding can also use other criteria such as a critical power density, indirectly reflecting the allowable thermal stress grinding process; the structure of the ground surface, which reflects the presence or absence of a defect layer, which is determined after the large number of experiments; flow range of the diamond layer.Optimal conditions should not exceed those of defect-free grinding. It is found that a maximum performance depends on the characteristics of circles and grade of processed material, as well as on the contact area and grinding conditions. Optimal performance depends on the diamond value (cost and specific consumption of diamonds in a circle.Above criteria require formalization as a function of the variable parameters of the grinding process. There is an option for the compromise of inter-criteria optimality, thereby providing a set of acceptable solutions, from

Development of a grinding-specific performance test set-up

DEFF Research Database (Denmark)

Olesen, C. G.; Larsen, B. H.; Andresen, E. L.

2015-01-01

The aim of this study was to develop a performance test set-up for America's Cup grinders. The test set-up had to mimic the on-boat grinding activity and be capable of collecting data for analysis and evaluation of grinding performance. This study included a literature-based analysis of grinding...... demands and a test protocol developed to accommodate the necessary physiological loads. This study resulted in a test protocol consisting of 10 intervals of 20 revolutions each interspersed with active resting periods of 50 s. The 20 revolutions are a combination of both forward and backward grinding...... and an exponentially rising resistance. A custom-made grinding ergometer was developed with computer-controlled resistance and capable of collecting data during the test. The data collected can be used to find measures of grinding performance such as peak power, time to complete and the decline in repeated grinding...

Development of a grinding-specific performance test set-up.

Science.gov (United States)

Olesen, C G; Larsen, B H; Andresen, E L; de Zee, M

2015-01-01

The aim of this study was to develop a performance test set-up for America's Cup grinders. The test set-up had to mimic the on-boat grinding activity and be capable of collecting data for analysis and evaluation of grinding performance. This study included a literature-based analysis of grinding demands and a test protocol developed to accommodate the necessary physiological loads. This study resulted in a test protocol consisting of 10 intervals of 20 revolutions each interspersed with active resting periods of 50 s. The 20 revolutions are a combination of both forward and backward grinding and an exponentially rising resistance. A custom-made grinding ergometer was developed with computer-controlled resistance and capable of collecting data during the test. The data collected can be used to find measures of grinding performance such as peak power, time to complete and the decline in repeated grinding performance.

Elucidating Grinding Mechanism by Theoretical and Experimental Investigations

Directory of Open Access Journals (Sweden)

AMM Sharif Ullah

2018-02-01

Full Text Available Grinding is one of the essential manufacturing processes for producing brittle or hard materials-based precision parts (e.g., optical lenses. In grinding, a grinding wheel removes the desired amount of material by passing the same area on the workpiece surface multiple times. How the topography of a workpiece surface evolves with these passes is thus an important research issue, which has not yet been addressed elaborately. The present paper tackles this issue from both the theoretical and the experimental points of view. In particular, this paper presents the results of experimental and theoretical investigations on the multi-pass surface grinding operations where the workpiece surface is made of glass and the grinding wheel consists of cBN abrasive grains. Both investigations confirm that a great deal of stochasticity is involved in the grinding mechanism, and the complexity of the workpiece surface gradually increases along with the number of passes.

Lathe converted for grinding aspheric surfaces

Science.gov (United States)

Larmer, J. W.; Levinsohn, M.; Mc Craw, D.; Pessagno, E. H.; Taub, F. J.

1964-01-01

A standard overarm tracing lathe converted by the addition of an independently driven diamond grinding wheel is used for grinding aspheric surfaces. The motion of the wheel is controlled by the lathe air tracer following the template which produces the desired aspheric profile.

Laser-assisted turning of components made of silicon-nitride ceramics

International Nuclear Information System (INIS)

Klocke, F.; Bausch, S.

2001-01-01

The manufacture of high-precision parts made of silicon-nitride ceramic, such as roller bearing rings or valves, currently involves finishing in the form of time and cost intensive grinding operations. This has resulted in demands for the development of more efficient machining techniques and for the subsequent provision of these within a manufacturing environment. A prototype of a precision lathe with an integrated high power diode laser for laser-assisted turning has been developed at the Fraunhofer IPT in close co-operation with industrial partners. When the workpiece is heated continuously by the laser, the resultant localized material softening enables the ceramic to be machined using a defined cutting edge. The application of this technique allows complex silicon nitride ceramic parts with surface qualities of up to R a = 0.3 μm to be produced considerably more flexibly than before, with no requirement for cooling lubricant. (author)

A Review of Literature on analysis of JIG Grinding Process

DEFF Research Database (Denmark)

Sudheesh, P. K.; Puthumana, Govindan

2016-01-01

in jig grinding, because of their uniformity and purity. In this paper, abrief review of the analysis of jig grinding process considering various research trends is presented. The areas highlighted are: optimization, selection of abrasives, selection of processing conditions and practical considerations....... The optimization of parameters in jig grinding process is important to maximize productivity and to improve quality. The abrasives of hard jig grinding wheels get blunt quickly so these are recommended to grind workpiece of low hardness and soft grinding wheels are recommended for hard material workpieces. The jig...

Dynamic Effects of the Earth's Rotation Caused by the Annual and Semi-Annual Cyclic Mass Redistribution of the Planet

Directory of Open Access Journals (Sweden)

M. Yu. Barkin

2016-01-01

Full Text Available The paper deals with development of the theory of perturbed rotational motion of a celestial body with variable geometry of the masses. Its main task is to study the impact of annual and semi-annual variations of the Earth's mass geometry (a component of its inertia tensor, as well as a component of its relative angular momentum, on the movement of the Earth's poles and its axial rotation. The body is considered to be a free (isolated, and the problem formulation corresponds to the classical Liouville problem on rotation of a variable body. Euler conical movement of the axially symmetric body with an arbitrary constant half-angle  is assumed as the unperturbed motion. In the classical theory of the Earth's rotation this angle is usually assumed to be zero.In the last 20 years, accuracy to determine the Earth rotation parameters owing to using methods of space geodesy and method of Very Long Baseline Interferometry (VLBI has increased by about three orders of magnitude and has made about  i.e., in angle measure it is about 10 - 20 arc-microseconds. According to experts, the theory of the Earth's rotation with such precision is not created yet. The paper is focused just on the new dynamic studies of the Earth rotation at a higher level of accuracy than has been done in previous studies, using a new approach to the problem, based on the new forms of the equations of motion (in the Andoyer variables and the analytical methods of perturbation theory (small parameter method.The problem of perturbed rotational motion with variable geometry and variable mass relative angular momentum in the first approximation is solved in Andoyer variables and projections of the angular velocity of the planet rotation. The analytical solution allows us to run applications to study dynamic effects from above factors for various bodies in the solar system, including the Earth. The solution allowed us to obtain the following parameters of the fundamental effects in the

Experimental verification of nanoparticle jet minimum quantity lubrication effectiveness in grinding

International Nuclear Information System (INIS)

Jia, Dongzhou; Li, Changhe; Zhang, Dongkun; Zhang, Yanbin; Zhang, Xiaowei

2014-01-01

In our experiment, K-P36 precision numerical control surface grinder was used for dry grinding, minimum quantity lubrication (MQL) grinding, nanoparticle jet MQL grinding, and traditional flood grinding of hardened 45 steel. A three-dimensional dynamometer was used to measure grinding force in the experiment. In this research, experiments were conducted to measure and calculate specific tangential grinding force, frictional coefficient, and specific grinding energy, thus verifying the lubrication performance of nanoparticles in surface grinding. Findings present that compared with dry grinding, the specific tangential grinding force of MQL grinding, nanoparticle jet MQL grinding, and flood grinding decreased by 45.88, 62.34, and 69.33 %, respectively. Their frictional coefficient was reduced by 11.22, 29.21, and 32.18 %, and the specific grinding energy declined by 45.89, 62.34, and 69.45 %, respectively. Nanoparticle jet MQL presented ideal lubrication effectiveness, which was attributed to the friction oil film with strong antifriction and anti-wear features formed by nanoparticles on the grinding wheel/workpiece interface. Moreover, lubricating properties of nanoparticles of the same size (50 nm) but different types were verified through experimentation. In our experiment, ZrO 2 nanoparticles, polycrystal diamond (PCD) nanoparticles, and MoS 2 nanoparticles were used in the comparison of nanoparticle jet MQL grinding. The experimental results manifest that MoS 2 nanoparticles exhibited the optimal lubricating effectiveness, followed by PCD nanoparticles. Our research also integrated the properties of different nanoparticles to analyze the lubrication mechanisms of different nanoparticles. The experiment further verified the impact of nanoparticle concentration on the effectiveness of nanoparticle jet MQL in grinding. The experimental results demonstrate that when the nanoparticle mass fraction was 6 %, the minimum specific tangential grinding force

Fundamentals of grinding : surface conditions of ground WC-Co systems

NARCIS (Netherlands)

Hegeman, JBJW; De Hosson, JTM; Shulepov, SY; Lousberg, N; de With, G; Brebbia, CA; Kenny, JM

1999-01-01

This paper concentrates on the fundamentals of grinding of inorganic materials. A statistical grinding model was developed based on the topography of the grinding wheel. The results of the model are compared with the results of grinding experiments on WC-Co hardmetals. The calculated profiles and

Manufacturing processes 2 grinding, honing, lapping

CERN Document Server

Klocke, Fritz

2009-01-01

Presents a view of the most common machining and non-machining manufacturing processes. This volume describes the characteristics of abrasive tools, their design and manufacturing, followed by the fundamentals of grinding fluids. It also discusses grinding of different materials (steel, cast iron, hard and brittle materials, nickel and titanium).

Modeling and simulation for fewer-axis grinding of complex surface

Science.gov (United States)

Li, Zhengjian; Peng, Xiaoqiang; Song, Ci

2017-10-01

As the basis of fewer-axis grinding of complex surface, the grinding mathematical model is of great importance. A mathematical model of the grinding wheel was established, and then coordinate and normal vector of the wheel profile could be calculated. Through normal vector matching at the cutter contact point and the coordinate system transformation, the grinding mathematical model was established to work out the coordinate of the cutter location point. Based on the model, interference analysis was simulated to find out the right position and posture of workpiece for grinding. Then positioning errors of the workpiece including the translation positioning error and the rotation positioning error were analyzed respectively, and the main locating datum was obtained. According to the analysis results, the grinding tool path was planned and generated to grind the complex surface, and good form accuracy was obtained. The grinding mathematical model is simple, feasible and can be widely applied.

Metallography and thermal analysis of ceramic nuclear fuels

International Nuclear Information System (INIS)

Tebaldi, V.

1988-01-01

The book contains two parts: the ceramography laboratory and the thermal treatment laboratory. After general remarks on sintering the first part includes sample preparation for ceramography (grinding, polishing, etching), microscopic examination and quantitative image analysis. The second part deals with temperature measurement, oxide/metal ratio determination, thermogravimetry, differential thermal analysis (DTA), melting point determination and constitution of phase diagrams. Installation of a Pu laboratory, sample decontamination, and research with a microprobe are described. 188 photomicrographs present the microstructure of ceramics based on U, Pu and higher actinides

Energy-effective Grinding of Inorganic Solids Using Organic Additives.

Science.gov (United States)

Mishra, Ratan K; Weibel, Martin; Müller, Thomas; Heinz, Hendrik; Flatt, Robert J

2017-08-09

We present our research findings related to new formulations of the organic additives (grinding aids) needed for the efficient grinding of inorganic solids. Even though the size reduction phenomena of the inorganic solid particles in a ball mill is purely a physical process, the addition of grinding aids in milling media introduces a complex physicochemical process. In addition to further gain in productivity, the organic additive helps to reduce the energy needed for grinding, which in the case of cement clinker has major environmental implications worldwide. This is primarily due to the tremendous amounts of cement produced and almost 30% of the associated electrical energy is consumed for grinding. In this paper, we examine the question of how to optimize these grinding aids linking molecular insight into their working mechanisms, and also how to design chemical additives of improved performance for industrial comminution.

Dynamic fatigue of a lithia-alumina-silica glass-ceramic

Science.gov (United States)

Tucker, Dennis S.

1990-01-01

A dynamic fatigue study was performed on a Li2O-Al2O3-SiO2 glass-ceramic in order to assess its susceptibility to delayed failure. Fracture mechanics techniques were used to analyze the results for the purpose of making lifetime predictions for optical elements made from this material. The material has reasonably good resistance (N = 20) to stress corrosion in ambient conditions. Analysis also indicated the elements should survive applied stresses incurred during grinding and polishing operations.

Machinability of IPS Empress 2 framework ceramic.

Science.gov (United States)

Schmidt, C; Weigl, P

2000-01-01

Using ceramic materials for an automatic production of ceramic dentures by CAD/CAM is a challenge, because many technological, medical, and optical demands must be considered. The IPS Empress 2 framework ceramic meets most of them. This study shows the possibilities for machining this ceramic with economical parameters. The long life-time requirement for ceramic dentures requires a ductile machined surface to avoid the well-known subsurface damages of brittle materials caused by machining. Slow and rapid damage propagation begins at break outs and cracks, and limits life-time significantly. Therefore, ductile machined surfaces are an important demand for machine dental ceramics. The machining tests were performed with various parameters such as tool grain size and feed speed. Denture ceramics were machined by jig grinding on a 5-axis CNC milling machine (Maho HGF 500) with a high-speed spindle up to 120,000 rpm. The results of the wear test indicate low tool wear. With one tool, you can machine eight occlusal surfaces including roughing and finishing. One occlusal surface takes about 60 min machining time. Recommended parameters for roughing are middle diamond grain size (D107), cutting speed v(c) = 4.7 m/s, feed speed v(ft) = 1000 mm/min, depth of cut a(e) = 0.06 mm, width of contact a(p) = 0.8 mm, and for finishing ultra fine diamond grain size (D46), cutting speed v(c) = 4.7 m/s, feed speed v(ft) = 100 mm/min, depth of cut a(e) = 0.02 mm, width of contact a(p) = 0.8 mm. The results of the machining tests give a reference for using IPS Empress(R) 2 framework ceramic in CAD/CAM systems. Copyright 2000 John Wiley & Sons, Inc.

Structure and properties of hot-pressed boron carbide ceramics

Energy Technology Data Exchange (ETDEWEB)

Koval' chenko, M S; Tkachenko, IU G; Koval' chuk, V V; Iurchenko, D Z; Satanin, S V [Institut Problem Materialovedeniia, Kiev (Ukrainian SSR)

1990-07-01

The microstructure and strength of B4C-TiB2-TiO{sub 2} ceramics samples, hot-compacted from a mixture of two types of B4C-TiO2-C powder, are examined. The two types are obtained by combining boric acid with either sucrose or carbon black. The grain-sizes of the two powders are found to be distinctly different from one another both before and after the grinding procedure and the degree of dispersion is not high. The strength tests show 600 MPa, the Vicker's hardness is 34.5 GPa, and the crack resistance coefficient of ceramics containing 15 percent TiB2 by mass is 5 MPa m exp 1/2. The use of soluble boron carbide powder helps achieve higher levels of strength and crack resistance. 5 refs.

Ceramic transactions: Environmental and waste management issues in the ceramic industry. Volume 39

International Nuclear Information System (INIS)

Mellinger, G.B.

1994-01-01

A symposium on environmental and waste management issues in the ceramic industry took place in Cincinnati, Ohio, April 19-22, 1993. The symposium was held in conjunction with the 95th Annual Meeting of the American Ceramic Society and was sponsored by the Ceramic Manufacturing Council, Legislative and Regulatory Affairs Committee with the Glass and Optical Materials, Basic Science, Cements, Nuclear, Refractory Ceramics, Structural Clay Products, Whitewares, Design, Electronics, Engineering Ceramics, and Materials and Equipment Divisions. This volume documents several of the papers that were presented at the symposium. Papers presented in this volume are categorized under the following headings: vitrification of hazardous and mixed wastes; waste glass properties and microstructure; processing of nuclear waste disposal glasses; waste form qualification; glass dissolution: modeling and mechanisms; systems and field testing of waste forms

Mechanism and experimental research on ultra-precision grinding of ferrite

Science.gov (United States)

Ban, Xinxing; Zhao, Huiying; Dong, Longchao; Zhu, Xueliang; Zhang, Chupeng; Gu, Yawen

2017-02-01

Ultra-precision grinding of ferrite is conducted to investigate the removal mechanism. Effect of the accuracy of machine tool key components on grinding surface quality is analyzed. The surface generation model of ferrite ultra-precision grinding machining is established. In order to reveal the surface formation mechanism of ferrite in the process of ultraprecision grinding, furthermore, the scientific and accurate of the calculation model are taken into account to verify the grinding surface roughness, which is proposed. Orthogonal experiment is designed using the high precision aerostatic turntable and aerostatic spindle for ferrite which is a typical hard brittle materials. Based on the experimental results, the influence factors and laws of ultra-precision grinding surface of ferrite are discussed through the analysis of the surface roughness. The results show that the quality of ferrite grinding surface is the optimal parameters, when the wheel speed of 20000r/mm, feed rate of 10mm/min, grinding depth of 0.005mm, and turntable rotary speed of 5r/min, the surface roughness Ra can up to 75nm.

Bruxism (Teeth Grinding or Clenching) (For Parents)

Science.gov (United States)

... Staying Safe Videos for Educators Search English Español Bruxism (Teeth Grinding or Clenching) KidsHealth / For Parents / Bruxism ( ... called bruxism , which is common in kids. About Bruxism Bruxism is the medical term for the grinding ...

Performing in-feed type centerless grinding process on a surface grinder

International Nuclear Information System (INIS)

Xu, W.; Wu, Y.; Sato, T.; Lin, W.

2011-01-01

In our previous study, a new centerless grinding method using surface grinder was proposed. In this method, centerless grinding operations are performed by installing a compact centerless grinding unit, consisting mainly of an ultrasonic elliptic-vibration shoe, a blade and their respective holders, on the worktable of a surface grinder. During grinding, the cylindrical workpiece is held on the ultrasonic shoe and the blade, and its rotational motion is controlled by the elliptic motion of the shoe end-face. An actual unit had been produced and its performance in tangential-feed type centerless grinding using a surface grinder had been confirmed in the previous workd. In this paper, the performance of the grinding unit in in-feed centerless grinding operation was confirmed, and the effects of the main process parameter, i.e., eccentric angle, on the workpiece roundness was investigated experimentally. The obtained results showed that: (1) the centerless grinding unit performed well in in-feed type centerless grinding; (2) the eccentric angle affects roundness significantly, and its optimal angle is 6 deg.; (3) the workpiece roundness can be further improved by varying the eccentric angle during grinding, and the final roundness reached 0.65 μm after grinding as the eccentric angle varied from 9 deg. to 6 deg. and to 3 deg.

30 CFR 77.401 - Stationary grinding machines; protective devices.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Stationary grinding machines; protective... OF UNDERGROUND COAL MINES Safeguards for Mechanical Equipment § 77.401 Stationary grinding machines; protective devices. (a) Stationary grinding machines other than special bit grinders shall be equipped with...

Occlusal Grinding Pattern during Sleep Bruxism and Temporomandibular Disorder

Directory of Open Access Journals (Sweden)

Yeni Wijaya

2013-09-01

Full Text Available Sleep Bruxism is a significant etiology of temporomandibular disorder (TMD and causes many dental or oral problems such as tooth wear or facet. There is no study analyzing the relationship between sleep bruxism and TMD. Objective: To investigate any relationship between occlusal grinding pattern during sleep bruxism and temporomandibular disorder. Methods: A cross-sectional study involving 30 sleep bruxism patients attended the Faculty Dentistry Universitas Indonesia Teaching Hospital (RSGMP FKG UI. Completion of 2 forms of ID-TMD index and questionnaire from American Academy of Sleep Medicine were done. BruxChecker was fabricated and used for two nights to record the occlusal grinding pattern. The occlusal grinding pattern was categorized into laterotrusive grinding (LG and mediotrusive side. Further divisons of LG were: incisor-canine (IC, incisor-caninepremolar (ICP and incisor-canine-premolar-molar (ICPM. Mediotrusive side was classified as mediotrusive contact (MC and mediotrusive grinding (MG. Results: It was found that occlusal grinding pattern in non-TMD subjects were IC+MC, in subjects with mild TMD were ICP+MG and in subjects with moderate TMD were ICP+MG and ICPM+MG. TMJ was more significantly affected by ICP and ICPM grinding pattern than that of IC. Conclusion: There was a significant relationship between occlusal grinding pattern during sleep bruxism and TMD.DOI: 10.14693/jdi.v20i2.149

Experimental Study of Tool Wear and Grinding Forces During BK-7 Glass Micro-grinding with Modified PCD Tool

Science.gov (United States)

Pratap, A.; Sahoo, P.; Patra, K.; Dyakonov, A. A.

2017-09-01

This study focuses on the improvement in grinding performance of BK-7 glass using polycrystalline diamond micro-tool. Micro-tools are modified using wire EDM and performance of modified tools is compared with that of as received tool. Tool wear of different types of tools are observed. To quantify the tool wear, a method based on weight loss of tool is introduced in this study. Modified tools significantly reduce tool wear in comparison to the normal tool. Grinding forces increase with machining time due to tool wear. However, modified tools produce lesser forces thus can improve life of the PCD micro-grinding tool.

Development of Hi-Tech ceramics fabrication technologies - Development of advanced nuclear materials

Energy Technology Data Exchange (ETDEWEB)

Kang, Thae Kap; Park, Ji Youn; Kim, Sun Jae; Kim, Kyong Ho; Jung, Choong Hwan; Oh, Seok Jin [Korea Atomic Energy Res. Inst., Taejon (Korea, Republic of)

1994-07-15

The objective of the present work is to prepare the foundation of hi-tech ceramics fabrication technologies through developing important processes i.e., tape casting, sol-gel, single crystal growing, compacting and sintering, and grinding and machining processes. Tape casting process is essential to manufacture hard and functional thin plates and structural elements for some composite materials. For the fabrication of spherical mono-sized micropowders of oxides, sol-gel process has widely been used. Piezoelectric elements that are the core parts of the sensors of LPMS (loose part monitoring system) and ALMS (acoustic leakage monitoring system) are used in single crystal forms. Compacting and sintering processes are general methods for fabricating structural parts using powders. Grinding and machining processes are important to achieve the final dimensions and surface properties of the parts. (Author).

Fatigue Tests on Welded Joints Improved by Grinding

DEFF Research Database (Denmark)

Agerskov, Henning; Bjørnbak-Hansen, Jørgen; Olesen, John Forbes

The present project is a part of an investigation on the fatigue life of the welded structure of large two-stroke diesel engines. Of special interest has been a study of the improvement in fatigue life, due to grinding of the weld toes. The test series carried through showed a significant increase...... without grinding to approx. 6.4 for the test series with grinding. In one of the test series (No. 7), the crack initiation in most tests moved from the weld toe to the non-ground surface between the ground areas at the weld toes, due to the grinding....... in fatigue life due to the grinding, ranging from a factor of approx. 2.8 to infinity, depending on the load level. With the limited number of tests carried out, S-N lines have not been determined. However, the results obtained indicate a change in slope of the S-N line from approx. 3.0 for the test series...

Research on operation mode of abrasive grain during grinding

Science.gov (United States)

Ivanova, T. N.; Dement’ev, V. B.; Nikitina, O. V.

2018-03-01

The processing of materials by cutting with an abrasive tool is carried out by means of thousands of grains bonded together as a single whole. The quality of the abrasive tool is defined by cutting properties of abrasive grains and depends on features of spreading the temperature field in time and in the abrasive grain volume. Grains are exposed to heating and cooling during work. It leads to undesired effects such as a decrease of durability of grain retention in the binder, hardness, intensification of diffusion and oxidation processes between the binder and the grain, the occurrence of considerable temperature stresses in the grain itself. The obtained equation which allows calculation of temperature field of grain for one rotation of grinding wheel shows that the temperature of the wheel depends on grinding modes and thermophysical properties of abrasive material. Thus, as the time of contact of grain with processed material increases, the temperature in the cutting area rises. As thermophysical properties increase, the temperature in cutting area decreases. Thermal working conditions are determined to be different from each other depending on contact time of the grain and the material. For example, in case of creep-feed grinding, the peak value of temperature is higher than during multistep grinding; the depth of expansion is greater. While the speed of the thermal process in creep-feed grinding is 2-3 times lower than in multistep grinding, the gradient reduces 3-4 times. The analysis of machining methods shows that creep-feed grinding ensures greater depth of grain heating, a smaller heating rate and a reduced velocity gradient. It causes a decrease of probable allotropic modifications and prevents from occurring of heat strokes - cracking of grains due to high temperature falls. Consequently, it is necessary to employ creep-feed grinding to increase the efficiency of abrasive tool employing. Three operation modes of grinding wheel including blunting, full

CMIP5 land surface models systematically underestimate inter-annual variability of net ecosystem exchange in semi-arid southwestern North America.

Science.gov (United States)

MacBean, N.; Scott, R. L.; Biederman, J. A.; Vuichard, N.; Hudson, A.; Barnes, M.; Fox, A. M.; Smith, W. K.; Peylin, P. P.; Maignan, F.; Moore, D. J.

2017-12-01

Recent studies based on analysis of atmospheric CO2 inversions, satellite data and terrestrial biosphere model simulations have suggested that semi-arid ecosystems play a dominant role in the interannual variability and long-term trend in the global carbon sink. These studies have largely cited the response of vegetation activity to changing moisture availability as the primary mechanism of variability. However, some land surface models (LSMs) used in these studies have performed poorly in comparison to satellite-based observations of vegetation dynamics in semi-arid regions. Further analysis is therefore needed to ensure semi-arid carbon cycle processes are well represented in global scale LSMs before we can fully establish their contribution to the global carbon cycle. In this study, we evaluated annual net ecosystem exchange (NEE) simulated by CMIP5 land surface models using observations from 20 Ameriflux sites across semi-arid southwestern North America. We found that CMIP5 models systematically underestimate the magnitude and sign of NEE inter-annual variability; therefore, the true role of semi-arid regions in the global carbon cycle may be even more important than previously thought. To diagnose the factors responsible for this bias, we used the ORCHIDEE LSM to test different climate forcing data, prescribed vegetation fractions and model structures. Climate and prescribed vegetation do contribute to uncertainty in annual NEE simulations, but the bias is primarily caused by incorrect timing and magnitude of peak gross carbon fluxes. Modifications to the hydrology scheme improved simulations of soil moisture in comparison to data. This in turn improved the seasonal cycle of carbon uptake due to a more realistic limitation on photosynthesis during water stress. However, the peak fluxes are still too low, and phenology is poorly represented for desert shrubs and grasses. We provide suggestions on model developments needed to tackle these issues in the future.

Ductile mode grinding of reaction-bonded silicon carbide mirrors.

Science.gov (United States)

Dong, Zhichao; Cheng, Haobo

2017-09-10

The demand for reaction-bonded silicon carbide (RB-SiC) mirrors has escalated recently with the rapid development of space optical remote sensors used in astronomy or Earth observation. However, RB-SiC is difficult to machine due to its high hardness. This study intends to perform ductile mode grinding to RB-SiC, which produces superior surface integrity and fewer subsurface damages, thus minimizing the workload of subsequent lapping and polishing. For this purpose, a modified theoretical model for grain depth of cut of grinding wheels is presented, which correlates various processing parameters and the material characteristics (i.e., elastic module) of a wheel's bonding matrix and workpiece. Ductile mode grinding can be achieved as the grain depth of cut of wheels decreases to be less than the critical cut depth of workpieces. The theoretical model gives a roadmap to optimize the grinding parameters for ductile mode grinding of RB-SiC and other ultra-hard brittle materials. Its feasibility was validated by experiments. With the optimized grinding parameters for RB-SiC, the ductile mode grinding produced highly specular surfaces (with roughness of ∼2.2-2.8  nm Ra), which means the material removal mechanism of RB-SiC is dominated by plastic deformation rather than brittle fracture. Contrast experiments were also conducted on fused silica, using the same grinding parameters; this produced only very rough surfaces, which further validated the feasibility of the proposed model.

Exploration on Wire Discharge Machining Added Powder for Metal-Based Diamond Grinding Wheel on Wire EDM Dressing and Truing of Grinding Tungsten Carbide Material

Science.gov (United States)

Chow, H. M.; Yang, L. D.; Lin, Y. C.; Lin, C. L.

2017-12-01

In this paper, the effects of material removal rate and abrasive grain protrusion on the metal-based diamond grinding wheel were studied to find the optimal parameters for adding powder and wire discharge. In addition, this kind of electric discharge method to add powder on the metal-based diamond grinding wheel on line after dressing and truing will be applied on tungsten carbide to study the grinding material removal rate, grinding wheel wear, surface roughness, and surface micro-hardness.

Workpiece Temperature Variations During Flat Peripheral Grinding

Science.gov (United States)

Smirnov, Vitalii A.; Repko, Aleksandr V.

2018-06-01

The paper presents the results of researches of temperature variations during flat peripheral grinding. It is shown that the temperature variations of the workpiece can reach 25...30% of the average values, which can lead to some thermal defects. A nonlinear two-dimensional thermophysical grinding model is suggested. It takes into account local changes in the cutting conditions: the fluctuation of the cut layer and the cutting force, the thermal impact of the cutting grains, and the presence of surface cavities in the intermittent wheel. For the numerical solution of the problem, the method of finite differences is adapted. Researches of the method stability and convergence are made, taking into account the specific nature of the problem. A high accuracy of the approximation of the boundary conditions and the nonlinear heat equation is provided. An experimental verification of the proposed thermophysical model was carried out with the use of installation for simultaneous measurement of the grinding force and temperature. It is shown that the discrepancy between the theoretical and experimental values of the grinding temperature does not exceed 5%. The proposed thermophysical model makes it possible to predict with high accuracy the temperature variations during grinding by the wheel periphery.

Grinding as a method of meat texture evaluation.

Science.gov (United States)

Kenmegne Kamdem, A T; Hardy, J

1995-01-01

An electric grinder equipped with a torque/speed sensor was used to evaluate maximum grinding torque (T(max)) and total energy (TE) necessary to grind 150 g of uncooked meat. Texture profile analysis (TPA), relaxation and cutting tests were carried out and sample compositions were also determined. The degree of dependence between grinding, TPA, relaxation, cutting parameters and sample composition was checked. Results showed that grinding parameters (T(max) and TE) correlated better with TPA, relaxation and cutting parameters than with composition. In particular correlation coefficient of -0·92, -0·92 and 0·97 were obtained, respectively, between T(max) and relaxation percentage (%R), T(max) and destructuring coefficient at 25% conmpression (De(25)) and between T(max) and maximum cutting force (F(c)).

Machining variability impacts on the strength of a 'chair-side' CAD-CAM ceramic.

LENUS (Irish Health Repository)

Addison, Owen

2012-08-01

To develop a novel methodology to generate specimens for bi-axial flexure strength (BFS) determination from a \\'chair-side\\' CAD-CAM feldspathic ceramic with surface defect integrals analogous to the clinical state. The hypotheses tested were: BFS and surface roughness (R(a)) are independent of machining variability introduced by the renewal or deterioration of form-grinding tools and that a post-machining annealing cycle would significantly modify BFS.

Grinding Parts For Automatic Welding

Science.gov (United States)

Burley, Richard K.; Hoult, William S.

1989-01-01

Rollers guide grinding tool along prospective welding path. Skatelike fixture holds rotary grinder or file for machining large-diameter rings or ring segments in preparation for welding. Operator grasps handles to push rolling fixture along part. Rollers maintain precise dimensional relationship so grinding wheel cuts precise depth. Fixture-mounted grinder machines surface to quality sufficient for automatic welding; manual welding with attendant variations and distortion not necessary. Developed to enable automatic welding of parts, manual welding of which resulted in weld bead permeated with microscopic fissures.

ADM guidance-Ceramics: all-ceramic multilayer interfaces in dentistry.

Science.gov (United States)

Lohbauer, Ulrich; Scherrer, Susanne S; Della Bona, Alvaro; Tholey, Michael; van Noort, Richard; Vichi, Alessandro; Kelly, J Robert; Cesar, Paulo F

2017-06-01

This guidance document describes the specific issues involved in dental multilayer ceramic systems. The material interactions with regard to specific thermal and mechanical properties are reviewed and the characteristics of dental tooth-shaped processing parameters (sintering, geometry, thickness ratio, etc.) are discussed. Several techniques for the measurement of bond quality and residual stresses are presented with a detailed discussion of advantages and disadvantages. In essence no single technique is able to describe adequately the all-ceramic interface. Invasive or semi-invasive methods have been shown to distort the information regarding the residual stress state while non-invasive methods are limited due to resolution, field of focus or working depth. This guidance document has endeavored to provide a scientific basis for future research aimed at characterizing the ceramic interface of dental restorations. Along with the methodological discussion it is seeking to provide an introduction and guidance to relatively inexperienced researchers. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

7 CFR 58.726 - Cutting and grinding.

Science.gov (United States)

2010-01-01

... 7 Agriculture 3 2010-01-01 2010-01-01 false Cutting and grinding. 58.726 Section 58.726 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards... Procedures § 58.726 Cutting and grinding. The trimmed and cleaned cheese should be cut into sections of...

Microwave-assisted grinding of metallurgical coke

International Nuclear Information System (INIS)

Ruisanchez, E.; Juarez-Perez, E. J.; Arenillas, A.; Bermudez, J. M.; Menendez, J. A.

2014-01-01

Metallurgical cokes are composed of graphitic carbon (s2p2) and different inorganic compounds with very different capacities to absorb microwave radiation. Moreover, due to the electric conductivity shown by the metallurgical cokes, microwave radiation produces electric arcs or microplasmas, which gives rise to hot spots. Therefore, when these cokes are irradiated with microwaves some parts of the particle experiment a rapid heating, while some others do not heat at all. As a result of the different expansion and stress caused by thermal the shock, small cracks and micro-fissures are produced in the particle. The weakening of the coke particles, and therefore an improvement of its grind ability, is produced. This paper studies the microwave-assisted grinding of metallurgical coke and evaluates the grinding improvement and energy saving. (Author)

Twyman effect mechanics in grinding and microgrinding.

Science.gov (United States)

Lambropoulos, J C; Xu, S; Fang, T; Golini, D

1996-10-01

In the Twyman effect (1905), when one side of a thin plate with both sides polished is ground, the plate bends: The ground side becomes convex and is in a state of compressive residual stress, described in terms of force per unit length (Newtons per meter) induced by grinding, the stress (Newtons per square meter) induced by grinding, and the depth of the compressive layer (micrometers). We describe and correlate experiments on optical glasses from the literature in conditions of loose abrasive grinding (lapping at fixed nominal pressure, with abrasives 4-400 μm in size) and deterministic microgrinding experiments (at a fixed infeed rate) conducted at the Center for Optics Manufacturing with bound diamond abrasive tools (with a diamond size of 3-40 μm, embedded in metallic bond) and loose abrasive microgrinding (abrasives of less than 3 μm in size). In brittle grinding conditions, the grinding force and the depth of the compressive layer correlate well with glass mechanical properties describing the fracture process, such as indentation crack size. The maximum surface residual compressive stress decreases, and the depth of the compressive layer increases with increasing abrasive size. In lapping conditions the depth of the abrasive grain penetration into the glass surface scales with the surface roughness, and both are determined primarily by glass hardness and secondarily by Young's modulus for various abrasive sizes and coolants. In the limit of small abrasive size (ductile-mode grinding), the maximum surface compressive stress achieved is near the yield stress of the glass, in agreement with finite-element simulations of indentation in elastic-plastic solids.

A critical study of high efficiency deep grinding

International Nuclear Information System (INIS)

Johnstone, Iain

2002-01-01

The recent years, the aerospace industry in particular has embraced and actively pursued the development of stronger high performance materials, namely nickel based superalloys and hardwearing steels. This has resulted in a need for a more efficient method of machining, and this need was answered with the advent of High Efficiency Deep Grinding (HEDG). This relatively new process using Cubic Boron Nitride (CBN) electroplated grinding wheels has been investigated through experimental and theoretical means applied to two widely used materials, M50 bearing steel and IN718 nickel based superalloy. It has been shown that this grinding method using a stiff grinding centre such as the Edgetek 5-axis machine is a viable process. Using a number of experimental designs, produced results which were analysed using a variety of methods including visual assessment, sub-surface microscopy and surface analysis using a Scanning Electron Microscope (SEM), residual stress measurement using X-Ray Diffraction (XRD) techniques, Barkhausen Noise Amplitude (BNA) measurements, surface roughness and Vickers micro-hardness appraisal. It has been shown that the fundamentals of the HEDG process have been understood through experimental as well as theoretical means and that through the various thermal models used, grinding temperatures can be predicted to give more control over this dynamic process. The main contributions to knowledge are made up of a number of elements within the grinding environment, the most important being the demonstration of the HEDG effect, explanation of the phenomenon and the ability to model the process. It has also been shown that grinding is a dynamic process and factors such as wheel wear will result in a continuous change in the optimum grinding conditions for a given material and wheel combination. With the significance of these factors recognised, they can be accounted for within an industrial adaptive control scenario with the process engineer confident of a

Eco-efficiency of grinding processes and systems

CERN Document Server

Winter, Marius

2016-01-01

This research monograph aims at presenting an integrated assessment approach to describe, model, evaluate and improve the eco-efficiency of existing and new grinding processes and systems. Various combinations of grinding process parameters and system configurations can be evaluated based on the eco-efficiency. The book presents the novel concept of empirical and physical modeling of technological, economic and environmental impact indicators. This includes the integrated evaluation of different grinding process and system scenarios. The book is a valuable read for research experts and practitioners in the field of eco-efficiency of manufacturing processes but the book may also be beneficial for graduate students.

Metastable structure formation during high velocity grinding

International Nuclear Information System (INIS)

Samarin, A.N.; Klyuev, M.M.

1984-01-01

Metastable structures in surface layers of samples are; investigated during force high-velocity abrasive grinding. Samples of martensitic (40Kh13), austenitic (12Kh18N10T), ferritic (05Kh23Yu5) steels and some alloys, in particular KhN77TYuR (EhI437B), were grinded for one pass at treatment depth from 0.17 up to 2.6 mm. It is established that processes of homogenizing, recrystallization and coagulation are; developed during force high-velocity grinding along with polymorphic transformations in the zone of thermomechanical effect, that leads to changes of physical and mechanical properties of the surface

17 CFR 270.30b1-2 - Semi-annual report for totally-owned registered management investment company subsidiary of...

Science.gov (United States)

2010-04-01

...-owned registered management investment company subsidiary of registered management investment company...-owned registered management investment company subsidiary of registered management investment company... subsidiary of a registered management investment company need not file a semi-annual report on Form N-SAR if...

Grinding tool for making hemispherical bores in hard materials

Science.gov (United States)

Duran, E.L.

1985-04-03

A grinding tool for forming hemispherical bores in hard materials such as boron carbide. The tool comprises a hemicircular grinding bit, formed of a metal bond diamond matrix, which is mounted transversely on one end of a tubular tool shaft. The bit includes a spherically curved outer edge surface which is the active grinding surface of the tool. Two coolant fluid ports on opposite sides of the bit enable introduction of coolant fluid through the bore of the tool shaft so as to be emitted adjacent the opposite sides of the grinding bit, thereby providing optimum cooling of both the workpiece and the bit.

Study of the distribution of magnesium in zirconia-magnesia ceramic solid electrolytes

International Nuclear Information System (INIS)

Muccillo, R.; Nogueira, R.A.

1988-01-01

ZrO 2 : 3%MgO ceramic samples have been prepared according to three different experimental procedures in order to find out the best method for processing powders for the conformation of solid electrolytes for disposable oxygen sensors. These procedures were I) simple mechanical mixing, II) homogeneization in liquid medium, and III) homogeneization of the ceramic pellet by grinding, pressing and sintering. All samples have been analysed by electron microprobe and electrical resistivity measurements. The main results show the same degree of homogeneity and electrical resistivity are obtained for the specimens of the 2nd and 3rd group, whereas the specimens of the 1st group have non-homogeneous distribution of magnesium and scattered values of electrical resistivity. (author) [pt

Origin and type of flaws in heat engine ceramic materials and components

International Nuclear Information System (INIS)

Govila, R.K.

1995-01-01

A number of ceramic materials such as Silicon Nitrides and Carbides, Sialons, Whisker-Reinforced Ceramic Composites and Partially-Stabilized Zirconias (PSZs) have been developed for use as structural components in heat engine applications. The reliability and durability of a structural engine component is critically dependent on the size, density of distribution and location of flaws. This information is critical for the processing and design engineers in order to design structural components using suitable materials and thus minimize stress intensity. In general, the failure initiating flaws are associated or produced due to material impurity, processing methods and parameters, and fabrication techniques (machining and grinding). Examples of each type of flaws associated with material impurity, processing methods and fabrication techniques are illustrated

30 CFR 57.15014 - Eye protection when operating grinding wheels.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Eye protection when operating grinding wheels. 57.15014 Section 57.15014 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF... grinding wheels. Face shields or goggles in good condition shall be worn when operating a grinding wheel...

Electro-chemical grinding

Science.gov (United States)

Feagans, P. L.

1972-01-01

Electro-chemical grinding technique has rotation speed control, constant feed rates, and contour control. Hypersonic engine parts of nickel alloys can be almost 100% machined, keeping tool pressure at virtual zero. Technique eliminates galling and permits constant surface finish and burr-free interrupted cutting.

Mandibular condylar morphology for bruxers with different grinding patterns.

Science.gov (United States)

Tao, Jianxiang; Wu, Junhua; Zhang, Xuying

2016-07-01

The purpose of this study was to investigate the mandibular condylar morphology for bruxers with different grinding patterns. Condylar sectional morphology and condylar position of 30 subjects were determined by two viewers using cone beam computed tomography (CBCT) image data sets. The grinding patterns during sleep bruxism (SB) were determined objectively using a Brux-checker device.Chi-square tests were used for statistical analysis for the condylar morphology type between different tooth grinding patterns. Spearman's rank correlation coefficient was used for correlation analysis between condylar position and the canine guidance area during SB. Theincidence of condylarmorphologicaldivergence from idealwas35%.There isa significant difference in distribution of condylar morphology type between the group grinding (GG) and GG combined with mediotrusive side grinding (MG) (p < 0.05). There was no significant correlation between condylar position and canine guidance area during bruxism. MG during SB is associated with condylar morphology that is considered not to be ideal.

Design and experimental study of a micro-groove grinding wheel with spray cooling effect

Directory of Open Access Journals (Sweden)

Shi Chaofeng

2014-04-01

Full Text Available The effectiveness of grinding fluid supply has a crucial impact on grinding quality and efficiency in high speed grinding. In order to improve the cooling and lubrication, through in-depth research of self-inhaling internal cooling method and intermittent grinding mechanism, a new spray cooling method used in high speed grinding is proposed. By referring to the structure of bowl-shaped dispersion disk, the grinding wheel matrix with atomization ability is designed; through studying heat transfer of droplet collision and the influence of micro-groove on the boiling heat transfer, grinding segment with micro-groove is designed to enhance the heat flux of coolant and achieve maximum heat transfer between droplets and grinding contact zone. High-speed grinding experiments on GH4169 with the developed grinding wheel are carried out. The results show that with the micro-groove grinding wheel just 5.4% of pump outlet flow rate and 0.5% of spindle energy is needed to reduce the grinding temperature to 200 °C, which means the developed grinding wheel makes cooling high efficient and low energy consuming.

Fragmentation process of vitrified ceramic waste (VCW) aiming its incorporation in silico-aluminous refractory concrete for production of refractory bricks

International Nuclear Information System (INIS)

Gomes, L.B.; Brandalise, R.N.; Santos, V. dos; Bergmann, C.P.

2012-01-01

Ceramic industry generates large amounts of waste, usually disposed in landfills. Reuse could minimize their generation and provides sustainable solutions. However, the energy cost of grinding these waste becomes a hindrance to their reuse. This work aims to obtain particle sizes of vitrified ceramic waste (VCW) using a fast, efficient and low cost fragmentation process as well as its use in refractory concrete. The results shows a wide range of particle size of VCW, which can be used as a promising source of raw material for production of refractory concrete. (author)

30 CFR 56.15014 - Eye protection when operating grinding wheels.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Eye protection when operating grinding wheels... MINES Personal Protection § 56.15014 Eye protection when operating grinding wheels. Face shields or goggles in good condition shall be worn when operating a grinding wheel. [53 FR 32526, Aug. 25, 1988] ...

A Review: The Effect of Grinded Coal Bottom Ash on Concrete

Directory of Open Access Journals (Sweden)

Basirun Nurul Fasihah

2017-01-01

Full Text Available This paper offers a review on the use of grinded coal bottom ash (CBA on the concrete properties as demonstrated by strength test and microstructure test. Amount of CBA from power plant station was disposed in landfill because of the particle shape had a rough particles. By finding an alternative way to gain its surface area by grinding and used as replacement material as cement replacement may give a good side feedback on the strength and morphology of concrete. Most of the prior works studied on the grinded fly ash and grinded rice husk ash. The study on the influence of grinded CBA on the properties of concrete still limited and need more attention Therefore, the review on the effect of grinded CBA on the strength and microstructure of concrete are discussed.

Advanced ceramics: evaluation of the ground surface Cerâmicas avançadas: avaliação da superfície polida

Directory of Open Access Journals (Sweden)

E. C. Bianchi

2003-09-01

Full Text Available The aim of this research is to evaluate the influence of grinding and cutting conditions on surfaces of advanced ceramics ground with diamond grinding wheels containing a binding resin bond. The quality surface was analyzed by Scanning Electron Microscopy (SEM.O objetivo desta pesquisa é a avaliação da influência das condições de usinagem na superfície gerada de cerâmicas avançadas retificadas com rebolo diamantado com ligante resinóide. A qualidade superficial foi analisada utilizando-se a Microscopia Eletrônica de Varredura (MEV

A 6-DOF parallel bone-grinding robot for cervical disc replacement surgery.

Science.gov (United States)

Tian, Heqiang; Wang, Chenchen; Dang, Xiaoqing; Sun, Lining

2017-12-01

Artificial cervical disc replacement surgery has become an effective and main treatment method for cervical disease, which has become a more common and serious problem for people with sedentary work. To improve cervical disc replacement surgery significantly, a 6-DOF parallel bone-grinding robot is developed for cervical bone-grinding by image navigation and surgical plan. The bone-grinding robot including mechanical design and low level control is designed. The bone-grinding robot navigation is realized by optical positioning with spatial registration coordinate system defined. And a parametric robot bone-grinding plan and high level control have been developed for plane grinding for cervical top endplate and tail endplate grinding by a cylindrical grinding drill and spherical grinding for two articular surfaces of bones by a ball grinding drill. Finally, the surgical flow for a robot-assisted cervical disc replacement surgery procedure is present. The final experiments results verified the key technologies and performance of the robot-assisted surgery system concept excellently, which points out a promising clinical application with higher operability. Finally, study innovations, study limitations, and future works of this present study are discussed, and conclusions of this paper are also summarized further. This bone-grinding robot is still in the initial stage, and there are many problems to be solved from a clinical point of view. Moreover, the technique is promising and can give a good support for surgeons in future clinical work.

12 CFR 502.26 - How does OTS calculate the semi-annual assessment for savings and loan holding companies?

Science.gov (United States)

2010-01-01

... assessment for savings and loan holding companies? 502.26 Section 502.26 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY ASSESSMENTS AND FEES Assessments Savings and Loan Holding Companies-Calculation of Assessments § 502.26 How does OTS calculate the semi-annual assessment for savings and loan...

Technics study on high accuracy crush dressing and sharpening of diamond grinding wheel

Science.gov (United States)

Jia, Yunhai; Lu, Xuejun; Li, Jiangang; Zhu, Lixin; Song, Yingjie

2011-05-01

Mechanical grinding of artificial diamond grinding wheel was traditional wheel dressing process. The rotate speed and infeed depth of tool wheel were main technics parameters. The suitable technics parameters of metals-bonded diamond grinding wheel and resin-bonded diamond grinding wheel high accuracy crush dressing were obtained by a mount of experiment in super-hard material wheel dressing grind machine and by analysis of grinding force. In the same time, the effect of machine sharpening and sprinkle granule sharpening was contrasted. These analyses and lots of experiments had extent instruction significance to artificial diamond grinding wheel accuracy crush dressing.

National Institute for Global Environmental Change. Semi-annual report, July 1, 1991--December 31, 1991

Energy Technology Data Exchange (ETDEWEB)

Werth, G.C.

1992-04-01

This document is the Semi-Annual Report of the National Institute for Global Environmental Change for the reporting period July 1 to December 31, 1991. The report is in two parts. Part I presents the mission of the Institute, examples of progress toward that mission, a brief description of the revised management plan, and the financial report. Part II presents the statements of the Regional Center Directors along with progress reports of the projects written by the researchers themselves.

Characterization of Al{sub 2}O{sub 3}-Co ceramic composite obtained by high energy mill; Caracterizacao de composito ceramico Al{sub 2}O{sub 3}-CO obtido por moagem de alta energia (MAE)

Energy Technology Data Exchange (ETDEWEB)

Souza, J.L.; Assis, R.B. de; Carlos, E.M.; Oliveira, T.P.; Costa, F.A. da, E-mail: leonaldojs@hotmail.com [Universidade Federal do Rio Grande do Norte (PPGCEM/UFRN), Natal, RN (Brazil). Programa de Pos-Graduacao em Engenharia Mecanica

2014-07-01

This work aims to characterize the ceramic composite Al{sub 2}O3-Co obtained by high energy grinding. The composites were obtained by milling Al{sub 2}O{sub 3} and Co in a high energy mill at a speed of 400 rpm, in proportions of 5 to 20% Cobalt (Co). Ceramic composites with 5 and 20% cobalt were sintered at 1200 and 1300 ° C, with a 60-minute plateau and a heating rate of 10 ° C / min. The samples were characterized by X-ray diffraction (XRD), thermogravimetry and differential scanning calorimetry (TG / DSC) and scanning electron microscopy (SEM). The results show the significant effect of cobalt percentage and high energy grinding on the final properties of the Al{sub 2}O{sub 3} - Co ceramic composite, presenting satisfactory values for the composite with a 20% cobalt percentage, showing to be a promising material for application in cutting tools.

Assessment of Metallic Contaminants in Grinded Millet using ...

African Journals Online (AJOL)

OLUWASOGO

Separate grinding discs were used for different millet forms, while the same quantity of millet ... have bad effects on human health (Normayo et al, 2010, Edem et al, 2012 .... grinding discs to have close contact due to the hardness of the millet.

ZI-annual 1991. Annual for the brick and tile, structural ceramics and clay pipe industries. ZI-Jahrbuch 1991. Jahrbuch fuer die Ziegel-, Baukeramik- und Steinzeugroehren-Industrie

Energy Technology Data Exchange (ETDEWEB)

Schellbach, G [ed.

1991-01-01

This annual appearing in German and English gives information on important results of research development projects in Germany and the rest of Europe, and reports on technical innovations in plant and machinery for these industries. The content of the technical articles is concentrated on following main subjects: Drying of ceramic products, testing and improving the frost resistance of clay roofing tiles, improved static design and thermal insulation of brick structures. Subjects also dealt with in the field of environmental protection are fluorine binding and changes in the salts content of the brick/mortar system. (BWI).

Recognition of diamond grains on surface of fine diamond grinding wheel

Institute of Scientific and Technical Information of China (English)

Fengwei HUO; Zhuji JIN; Renke KANG; Dongming GUO; Chun YANG

2008-01-01

The accurate evaluation of grinding wheel sur-face topography, which is necessary for the investigation of the grinding principle, optimism, modeling, and simu-lation of a grinding process, significantly depends on the accurate recognition of abrasive grains from the measured wheel surface. A detailed analysis of the grain size distri-bution characteristics and grain profile wavelength of the fine diamond grinding wheel used for ultra-precision grinding is presented. The requirements of the spatial sampling interval and sampling area for instruments to measure the surface topography of a diamond grinding wheel are discussed. To recognize diamond grains, digital filtering is used to eliminate the high frequency disturb-ance from the measured 3D digital surface of the grinding wheel, the geometric features of diamond grains are then extracted from the filtered 3D digital surface, and a method based on the grain profile frequency characteris-tics, diamond grain curvature, and distance between two adjacent diamond grains is proposed. A 3D surface pro-filer based on scanning white light interferometry is used to measure the 3D surface topography of a #3000 mesh resin bonded diamond grinding wheel, and the diamond grains are then recognized from the 3D digital surface. The experimental result shows that the proposed method is reasonable and effective.

Evaluation of minimum quantity lubrication grinding with nano-particles and recent related patents.

Science.gov (United States)

Li, Changhe; Wang, Sheng; Zhang, Qiang; Jia, Dongzhou

2013-06-01

In recent years, a large number of patents have been devoted to developing minimum quantity lubrication (MQL) grinding techniques that can significantly improve both environmentally conscious and energy saving and costeffective sustainable grinding fluid alternatives. Among them, one patent is about a supply system for the grinding fluid in nano-particle jet MQL, which produced MQL lubricant by adding solid nano-particles in degradable grinding fluid. The MQL supply device turns the lubricant to the pulse drops with fixed pressure, unchanged pulse frequency and the same drop diameter. The drops will be produced and injected in the grinding zone in the form of jet flow under high pressure gas and air seal. As people become increasingly demanding on our environment, minimum quantity lubrication has been widely used in the grinding and processing. Yet, it presents the defect of insufficient cooling performance, which confines its development. To improve the heat transfer efficiency of MQL, nano-particles of a certain mass fraction can be added in the minimum quantity of lubricant oil, which concomitantly will improve the lubrication effects in the processing. In this study, the grinding experiment corroborated the effect of nano-particles in surface grinding. In addition, compared with other forms of lubrication, the results presented that the grinding force, the friction coefficient and specific grinding energy of MQL grinding have been significantly weakened, while G ratio greatly rose. These are attributed to the friction oil-film with excellent anti-friction and anti-wear performance, which is generated nano-particles at the wheel/workpiece interface. In this research, the cooling performance of nano-particle jet MQL was analyzed. Based on tests and experiments, the surface temperature was assayed from different methods, including flood lubricating oil, dry grinding, MQL grinding and nano-particle jet MQL grinding. Because of the outstanding heat transfer

The Y2BaCuO5 oxide as green pigment in ceramics

International Nuclear Information System (INIS)

Fernandez, F.; Colon, C.; Duran, A.; Barajas, R.; Llopis, J.; Paje, S.E.; Saez-Puche, R.; Julian, I.

1998-01-01

Fine particles of green yttrium-barium-copper-oxide pigments Y 2 BaCuO 5 have been prepared using two different synthesis methods. The process of combustion of mixed nitrates and urea needs a maximal temperature of 900 C and provides samples formed by aggregates of homogeneous small particles with a size of about 0.3 μm. However, the ceramic method requires 1050 C as synthesis temperature, and yields rather higher particle sizes. Even after grinding, these samples are formed by heterogeneous particles with mean sizes of about 3 μm. Diffuse reflectance spectra reveal that the samples obtained using the former method present a higher brilliancy, so they have been selected to be tested as green pigment in ceramics with good results. (orig.)

Grinding Method and Error Analysis of Eccentric Shaft Parts

Science.gov (United States)

Wang, Zhiming; Han, Qiushi; Li, Qiguang; Peng, Baoying; Li, Weihua

2017-12-01

RV reducer and various mechanical transmission parts are widely used in eccentric shaft parts, The demand of precision grinding technology for eccentric shaft parts now, In this paper, the model of X-C linkage relation of eccentric shaft grinding is studied; By inversion method, the contour curve of the wheel envelope is deduced, and the distance from the center of eccentric circle is constant. The simulation software of eccentric shaft grinding is developed, the correctness of the model is proved, the influence of the X-axis feed error, the C-axis feed error and the wheel radius error on the grinding process is analyzed, and the corresponding error calculation model is proposed. The simulation analysis is carried out to provide the basis for the contour error compensation.

Comparison of Wet and Dry Grinding in Electromagnetic Mill

Directory of Open Access Journals (Sweden)

Szymon Ogonowski

2018-03-01

Full Text Available Comparison of dry and wet grinding process in an electromagnetic mill is presented in this paper. The research was conducted in a batch copper ore grinding. Batch mode allows for precise parametrization and constant repetitive conditions of the experiments. The following key aspects were tested: processing time, feed size, size of the grinding media, mass of the material and graining media, and density of the pulp. The particles size distribution of the product samples was analyzed in the laboratory after each experiment. The paper discusses the experimental results as well as the concept of dry and wet grinding and classification circuits for the electromagnetic mill. The main points of the discussion are the size reduction effectiveness and power consumption of the entire system.

A dynamic model of cylindrical plunge grinding process for chatter phenomena investigation

Directory of Open Access Journals (Sweden)

Lajmert Paweł

2018-01-01

Full Text Available In the paper, chatter vibrations in the cylindrical plunge grinding process are investigated. An improved model of the grinding process was developed which is able to simulate self-excited vibrations due to a regenerative effect on the workpiece and the grinding wheel surface. The model includes a finite-element model of the workpiece, two degrees of freedom model of the grinding wheel headstock and a model of wheel-workpiece geometrical interferences. The model allows to studying the influence of different factors, i.e. workpiece and machine parameters as well as grinding conditions on the stability limit and a chatter vibration growth rate. At the end, simulation results are shown and compared with exemplified real grinding results.

Learning Activity Packets for Grinding Machines. Unit I--Grinding Machines.

Science.gov (United States)

Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

This learning activity packet (LAP) is one of three that accompany the curriculum guide on grinding machines. It outlines the study activities and performance tasks for the first unit of this curriculum guide. Its purpose is to aid the student in attaining a working knowledge of this area of training and in achieving a skilled or moderately…

Learning Activity Packets for Grinding Machines. Unit II--Surface Grinding.

Science.gov (United States)

Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

This learning activity packet (LAP) is one of three that accompany the curriculum guide on grinding machines. It outlines the study activities and performance tasks for the second unit of this curriculum guide. Its purpose is to aid the student in attaining a working knowledge of this area of training and in achieving a skilled or moderately…

Learning Activity Packets for Grinding Machines. Unit III--Cylindrical Grinding.

Science.gov (United States)

Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

This learning activity packet (LAP) is one of three that accompany the curriculum guide on grinding machines. It outlines the study activities and performance tasks for the third unit of this curriculum guide. Its purpose is to aid the student in attaining a working knowledge of this area of training and in achieving a skilled or moderately…

Safety of stationary grinding machines - impact resistance of work zone enclosures.

Science.gov (United States)

Mewes, Detlef; Adler, Christian

2017-09-01

Guards on machine tools are intended to protect persons from being injured by parts ejected with high kinetic energy from the work zone of the machine. Stationary grinding machines are a typical example. Generally such machines are provided with abrasive product guards closely enveloping the grinding wheel. However, many machining tasks do not allow the use of abrasive product guards. In such cases, the work zone enclosure has to be dimensioned so that, in case of failure, grinding wheel fragments remain inside the machine's working zone. To obtain data for the dimensioning of work zone enclosures on stationary grinding machines, which must be operated without an abrasive product guard, burst tests were conducted with vitrified grinding wheels. The studies show that, contrary to widely held opinion, narrower grinding wheels can be more critical concerning the impact resistance than wider wheels although their fragment energy is smaller.

Intra-pulp temperature increase of equine cheek teeth during treatment with motorized grinding systems: influence of grinding head position and rotational speed.

Science.gov (United States)

Haeussler, Silvia; Luepke, Matthias; Seifert, Hermann; Staszyk, Carsten

2014-02-21

In equine practice, teeth corrections by means of motorized grinding systems are standard procedure. The heat resulting from that treatment may cause irreparable damage to the dental pulp. It has been shown that a 5.5°C temperature rise may cause severe destruction in pulp cells. Hence, the capability to continuously form secondary dentine is lost, and may lead, due to equine-typical occlusal tooth abrasion, to an opening of the pulp cavity.To obtain reliable data on the intra-pulp increase in temperature during corrective treatments, equine cheek teeth (CT) were modified in a way (occlusal surface smoothed, apical parts detached, pulp horns standardized) that had been qualified in own former published studies. All parameters influencing the grinding process were standardized (force applied, initial temperatures, dimensions of pulp horns, positioning of grinding disk, rotational speed). During grinding experiments, imitating real dental treatments, the time span for an intra-pulp temperature increase of 5.5°C was determined. The minimum time recorded for an intra-pulp temperature increase of 5.5°C was 38 s in mandibular CT (buccal grinding, 12,000 rpm) and 70 s in maxillary CT (flat occlusal grinding, 12,000 rpm). The data obtained showed that doubling the rotational speed of the disk results in halving the time span after which the critical intra-pulp temperature increase in maxillary CT is reached. For mandibular CT, the time span even drops by two thirds. The use of standardized hypsodont CT enabled comparative studies of intra-pulp heating during the grinding of occlusal tooth surfaces using different tools and techniques. The anatomical structure of the natural vital hypsodont tooth must be kept in mind, so that the findings of this study do not create a deceptive sense of security with regard to the time-dependent heating of the native pulp.

Optimum condition determination of Rirang uranium ores grinding using ball mill

International Nuclear Information System (INIS)

Affandi, Kosim; Waluyo, Sugeng; Sarono, Budi; Sujono; Muhammad

2002-01-01

The grinding experiment on Rirang Uranium ore has been carried out with the aim is to find out the optimum condition of wet grinding using ball mill to produce particle size -325, -200 and -100 mesh. This will be used for decomposition feed the test was done by examine the parameters comparison of ore's weight against ball's weight and time of grinding. The test shown that the product of particle size -325 meshes was achieved optimum condition at the comparison ore's weight: ball = 1:3, grinding time 150 minutes, % solid 60, speed rotation of ball mill 60 rpm and recovery of grinding was 93.51 % of -325 mesh. The product of particle size -200 mesh was achieved optimum condition at comparison ore's weight: ball = 1:2, time of grinding 60 minutes, the fraction of + 200 mesh was regrind, the recovery of grinding 6.82% at particle size of (-200 + 250) mesh, 5.75 % at (-250 + 325)m mesh and, 47.93 % -325 mesh. The product of particle size -100 mesh was achieved the optimum condition at comparison ore's weight: ball = 1:2, time of grinding at 30 minutes particle size +100 mesh regrinding using mortar grinder, recovery of grinding 30.10% at particle size (-100 + 150) m, 12.28 % at (-150 + 200) mesh, 15.92 % at (-200 + 250) mesh, 12.44 % at (-250 + 325) mesh and 29.26 % -325 mesh. The determination of specific gravity of Rirang uranium ore was between 4.15 - 4.55 g/cm 3

Improving the plunge grinding technology efficiency through a rigid scheme use

Directory of Open Access Journals (Sweden)

І. О. Рябенков

2016-07-01

Full Text Available Theoretical bases of grinding technology researches results form the basis of this work. It has been shown that grinding efficiency increase can be achieved through the use of new kinematic grinding schemes and progressive designs of abrasive tools. However, not enough attention is paid to the calculation of the main technological machining parameters with due regard to separate processes of cutting and friction at grinding, thus restricting the effective application of these kinematic grinding schemes and scientifically grounded selection of optimal processing conditions. In this paper a mathematical model has been developed for determining the material removal rate and cutting force at plunge grinding, what made it possible to substantiate reducing the power strength at grinding and to increase productivity. Calculations revealed that the cutting force at plunge grinding is conditioned by the disk bond friction against the material being processed, the intensity of which in the course of processing time increases proportionally due to an increase of elastic movements in the technological system. Proceeding from these results the optimum grinding conditions based on the use of the abrasive disk that works under self-sharpening conditions, thus eliminating the disk bond friction against the material being processed, have been grounded. In this case, the abrasive disk provides complete removal of the processed material supplied to the cutting zone at the nominal speed of a workpiece movement. Also the ability to reduce cutting forces through the increase of the disk speed and the workpiece speed ratio has been shown

Preparation of Grinding Aid Using Waste Acid Residue from Plasticizer Plant

Science.gov (United States)

Li, Lingxiao; Feng, Yanchao; Liu, Manchao; Zhao, Fengqing

2017-09-01

The grinding aid for granulated blast-furnace slag were prepared from waste acid residue from plasticizer plant through neutralization, de-methanol and granulation process. In this process, sulfuric acid was transformed into gypsum which has much contribution for grinding effect by combined use with the glycerol and poly glycerin in the waste. Fly ash was used for granulation for the composite grinding aid. Methanol can be recycled in the process. The result showed that the suitable addition of grinding aid is 0.03 % of granulated blast-furnace slag (mass). In this case, the specific surface area is 14% higher than that of the blank. Compared with the common grinding aids, it has excellent performance and low cost.

Measurement of radiant properties of ceramic foam

International Nuclear Information System (INIS)

Hoornstra, J.; Turecky, M.; Maatman, D.

1994-07-01

An experimental facility is described for the measurement of the normal spectral and total emissivity and transmissivity of semi-transparent materials in the temperature range of 600 C to 1200 C. The set-up was used for the measurement of radiation properties of highly porous ceramic foam which is used in low NO x radiant burners. Emissivity and transmissivity data were measured and are presented for coated and uncoated ceramic foam of different thicknesses. (orig.)

Analysis of the influence of process conditions on the surface finish of ceramic materials manufactured by EDM

International Nuclear Information System (INIS)

Puertas-Arbizu, I.; Luis-Perez, C. J.

2004-01-01

Electrical discharge machining (EDM) is an emerging alternative versus some other manufacturing processes of conductive ceramic materials, such as: laser machining, electrochemical machining, abrasive water jet, ultrasonic machining and diamond wheel grinding. Due to its interest in the industrial field, in this work a study of the influence of process conditions on the surface aspect of three conductive ceramic materials: hot-pressed boron carbide (B 4 C), reaction-bonded silicon carbide (SiSiC) and cobalt-bonded tungsten carbide (WC-Co) is carried out. These materials are to be electrical discharge machined under different machining conditions and in the particular case of finish stages (Ra≤ 1 μm). (Author)

Development of ELID mirror surface grinding by cast iron bond grinding wheel. Ohkochi memorial technology prize; Chutetsu bond toishi ni yoru denkai inpurosesu doresshingu (ELID) kyomen kensakuho no kaihatsu. Okochi kinen gijutsusho jusho ni yosete

Energy Technology Data Exchange (ETDEWEB)

Omori, H.; Takahashi, I. [Institute of Physical and Chemical Research, Tokyo (Japan); Nakagawa, T. [The University of Tokyo, Tokyo (Japan). Institute of Industrial Science; Hagiuda, Y.; Karikome, K. [Tokyo Metropolitan College of Aeronautical Engineering, Tokyo (Japan)

1997-08-01

Development was accomplished on the electrolytic in-process dressing (ELID) mirror surface grinding process using a cast iron bonded grinding wheel. This paper describes the history of the development, which may be summarized as follows: a study was begun on powder forging of cutting chips in 1970; a research was started on powder forging of decarburized cast iron powder; developments were made on powder metallurgy of cast irons and cast iron bonded lapping tools in 1980, and cast iron bonded diamond grinding wheels were put on the market; a high-efficiency grinding process using MC and cast iron fiber-bonded grinding wheels were developed in 1985 and the grinding wheels made therefrom were put on the market; and a study was begun on the ELID grinding in 1987, and marketing was started on power supply, grinding liquid and tools for the ELID grinding process in 1990. Discussions on converting raw materials for the powder forging into cutting chips have triggered developing the cast iron bonded grinding wheel. The cast iron bonded diamond grinding wheel improves dressability and sharpness of conventional grinding wheels. The grinding wheel is fabricated by mixing carbonyl iron powder, diamond grinding grains and cast iron powder, pressing the mixture in a die, sintering it at 1140 degC, and assembling and dressing the sinter. The grinding stone can grind high-tech materials. 4 figs.

21 CFR 888.3410 - Hip joint metal/polymer or ceramic/polymer semiconstrained resurfacing cemented prosthesis.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Hip joint metal/polymer or ceramic/polymer... Devices § 888.3410 Hip joint metal/polymer or ceramic/polymer semiconstrained resurfacing cemented prosthesis. (a) Identification. A hip joint metal/polymer or ceramic/polymer semi-constrained resurfacing...

Critical study of high efficiency deep grinding

OpenAIRE

Johnstone, lain

2002-01-01

The recent years, the aerospace industry in particular has embraced and actively pursued the development of stronger high performance materials, namely nickel based superalloys and hardwearing steels. This has resulted in a need for a more efficient method of machining, and this need was answered with the advent of High Efficiency Deep Grinding (HEDG). This relatively new process using Cubic Boron Nitride (CBN) electroplated grinding wheels has been investigated through experim...

Decapsulation Method for Flip Chips with Ceramics in Microelectronic Packaging

Science.gov (United States)

Shih, T. I.; Duh, J. G.

2008-06-01

The decapsulation of flip chips bonded to ceramic substrates is a challenging task in the packaging industry owing to the vulnerability of the chip surface during the process. In conventional methods, such as manual grinding and polishing, the solder bumps are easily damaged during the removal of underfill, and the thin chip may even be crushed due to mechanical stress. An efficient and reliable decapsulation method consisting of thermal and chemical processes was developed in this study. The surface quality of chips after solder removal is satisfactory for the existing solder rework procedure as well as for die-level failure analysis. The innovative processes included heat-sink and ceramic substrate removal, solder bump separation, and solder residue cleaning from the chip surface. In the last stage, particular temperatures were selected for the removal of eutectic Pb-Sn, high-lead, and lead-free solders considering their respective melting points.

Four Mile Creek semi-annual sampling report, January 1993 sampling event

International Nuclear Information System (INIS)

1993-05-01

From 1955 to 1988 low-level radioactive wastewater generated by chemical separation processes within the General Separations Area (GSA) was discharged to seepage basins in the F and H Areas of the Savannah River Site (SRS). These basins were designed to permit the infiltration of the process wastewaters. As wastewater percolated downward through the basins, chemical and radioactive constituents were retained or sequestered in the subsoils. An extensive study aimed at characterizing the groundwater seeping into Four Mile Creek and its associated seepline was conducted in 1988 and 1989 (Haselow et al. 1990). Results of this study suggested that contaminants leaching from the F and H Area seepage basins were impacting the Four Mile Creek wetland system. The seepage basins were closed in 1988 and capped and sealed in 1990. This effectively eliminated the source of the contaminants and the hydraulic head driving the migration of contaminants from the basins. It has been hypothesized that, after the elimination of the source and head, annual rainfall amounts would be sufficient to dilute and flush out contaminants remaining in the subsoils and groundwaters beneath the basins. Westinghouse Savannah River Company has designed a semi-annual sampling and analytical program for the Four Mile Creek (FMC) seepline and stream water to test the hypothesis. This report summarizes field monitoring activities from January 25, 1993 to February 4, 1993

Grinding temperature and energy ratio coefficient in MQL grinding of high-temperature nickel-base alloy by using different vegetable oils as base oil

OpenAIRE

Li Benkai; Li Changhe; Zhang Yanbin; Wang Yaogang; Jia Dongzhou; Yang Min

2016-01-01

Vegetable oil can be used as a base oil in minimal quantity of lubrication (MQL). This study compared the performances of MQL grinding by using castor oil, soybean oil, rapeseed oil, corn oil, sunflower oil, peanut oil, and palm oil as base oils. A K-P36 numerical-control precision surface grinder was used to perform plain grinding on a workpiece material with a high-temperature nickel base alloy. A YDM–III 99 three-dimensional dynamometer was used to measure grinding force, and a clip-type t...

Gemstone Grinding Process Improvement by using Impedance Force Control

Directory of Open Access Journals (Sweden)

Hamprommarat Chumpol

2015-01-01

Full Text Available Chula Automatic Faceting Machine has been developed by The Advance Manufacturing Research Lab, Chulalongkorn University to support Thailand Gems-Industry. The machine has high precision motion control by using position and force control. A contact stiffness model is used to estimate grinding force. Although polished gems from the Faceting Machine have uniform size and acceptable shape, the force of the grinding and polishing process cannot be maintain constant and has some fluctuation due to indirect force control. Therefor this research work propose a new controller for this process based on an impedance direct force control to improve the gemstone grinding performance during polishing process. The grinding force can be measured through motor current. The results show that the polished gems by using impedance direct force control can maintain uniform size as well as good shape and high quality surface.

Effects of grinding on certain crystalline structures

International Nuclear Information System (INIS)

Tekiz, Y.

1965-06-01

The effects of grinding on certain crystalline substances (ZnO, ZnS, Sb), have been studied using X-ray diffraction and electron microscopy. The treatments were carried out using a vibrating mill which involves a higher energy than more conventional equipment such as ball-mills. Various methods have been proposed for determining the width of the intrinsic profile (β). In the case of zinc oxide it has been shown possible to differentiate the respective contributions of the fragmentation effects and of lattice deformation effects to the overall effects of the grinding. For the two types of zinc sulfide (blend and Wurtzite) it has been shown that the blend-wurtzite) transition point is very much decreased, and that the rate of transformation of wurtzite into the stable form (blend) at room temperature is considerably increased by the grinding. In the case of antimony, the method of fragmentation shows the existence of an anisotropy which appears to be connected with easily cleavable planes. These observations show that in the case of grinding carried out with sufficient energy, the accumulation of this energy in the matter through the creation of lattice defects can accelerate the reaction rate or bring about physical transformations. (author) [fr

Performance of Metal Cutting on Endmills Manufactured by Cooling-Air and Minimum Quantity Lubrication Grinding

Science.gov (United States)

Inoue, Shigeru; Aoyama, Tojiro

Grinding fluids have been commonly used during the grinding of tools for their cooling and lubricating effect since the hard, robust materials used for cutting tools are difficult to grind. Grinding fluids help prevent a drop in hardness due to burning of the cutting edge and keep chipping to an absolute minimum. However, there is a heightened awareness of the need to improve the work environment and protect the global environment. Thus, the present study is aimed at applying dry grinding, cooling-air grinding, cooling-air grinding with minimum quantity lubrication (MQL), and oil-based fluid grinding to manufacturing actual endmills (HSS-Co). Cutting tests were performed by a vertical machining center. The results indicated that the lowest surface inclination values and longest tool life were obtained by cooling-air grinding with MQL. Thus, cooling-air grinding with MQL has been demonstrated to be at least as effective as oil-based fluid grinding.

Development of the pellet grinding and inspection system

International Nuclear Information System (INIS)

Yamaguchi, Toshihiro; Kawasaki, Takao; Inui, Toshihiko; Yamada, Hiroyuki.

1996-01-01

The pellet grinding and inspection system is the facility of producing the MOX fuel for FBRs, and it was delivered in March, 1996 to the No. 3 Development Office of the plutonium fuel shop in Tokai of Power Reactor and Nuclear Fuel Development Corporation. This facility realized the high speed processing using the compact facility by combining the grinding of pellets, the inspection of outer density and appearance, the rationalization of the facility and the high performance automation equipment. The production processes of MOX comprise the processes of powder, sinter, finish and inspection, fabrication and assembling. The requirement for developing these facilities is shown. The features of this pellet grinding and inspection system are the compact facility by the combination of functions, high speed processing, the reduction of holdup in processes and the improvement of maintenance. These features are explained. The main components are simple sorting equipment, grinder, grinding dust recovering equipment, outside diameter and density sorting equipment and appearance inspection equipment. The constitution and the main functions of the control facility are described. The operational process is explained. (K.I.)

Potentiality of a frit waste from ceramic sector as raw material to glass-ceramic material production; Potencialidad de un residuo de frita procedente del sector ceramico como materia prima para la produccion de material vitroceramico

Energy Technology Data Exchange (ETDEWEB)

Barrachina Albert, E.; Llop Pla, J.; Notari Abad, M. D.; Carda Castello, J. B.

2015-10-01

This work consists of studying the devitrification capacity of a residue from sodium-calcium frit, using the vitreous powder sintering method, which follows the traditional ceramic processing route, including a specific heat treatment to generate the appearance of crystals from the original glass phase. Initially the frit residue has been characterized by instrumental techniques such as XRF, XRD and DTA/TG. Furthermore, the chemical analysis (XRF) has allowed the prediction of devitrification potentiality of this residue by theoretical approaches represented by Gingsberg, Raschin-Tschetverikov and Lebedeva ternary diagrams. Then, this residue was subjected to traditional ceramic method, by changing the grinding time, the pressing pressure and prepared samples were obtained at different temperatures. In this part, the techniques for measuring particle size by laser diffraction and XRD and SEM to evaluate the generated crystalline phases, were applied. Finally, it has been found that this frit residue works as glass-ceramic precursor, devitrifying in wollastonite crystals as majority phase and without being subjected to the melting step of the glass-ceramic typical method. (Author)

Investigation of the formation process of two piracetam cocrystals during grinding

DEFF Research Database (Denmark)

Rehder, Sönke; Klukkert, Marten; Löbmann, Korbinian

2011-01-01

Cocrystal formation rates during dry grinding and liquid-assisted grinding were investigated by X-ray powder diffractometry and Raman spectroscopy. Two polymorphic forms of piracetam were used to prepare known piracetam cocrystals as model substances, i.e.,piracetam-citric acid and piracetam......-tartaric acid cocrystals. Raman spectroscopy in combination with principal component analysis was used to visualize the cocrystal formation pathways. During dry grinding, cocrystal formation appeared to progress via an amorphous intermediate stage, which was more evident for the piracetam-citric acid than...... for the piracetam-tartaric acid cocrystal. It was shown that liquid-assisted grinding led to faster cocrystal formation than dry grinding, which may be explained by the higher transformation rate due to the presence of liquid. The cocrystal formation rate did not depend on the applied polymorphic form...

Determining the direction of tooth grinding: an in vitro study.

Science.gov (United States)

ten Berge, F; te Poel, J; Ranjitkar, S; Kaidonis, J A; Lobbezoo, F; Hughes, T E; Townsend, G C

2012-08-01

The analysis of microwear patterns, including scratch types and widths, has enabled reconstruction of the dietary habits and lifestyles of prehistoric and modern humans. The aim of this in vitro study was to determine whether an assessment of microwear features of experimental scratches placed on enamel, perpendicularly to the direction of grinding, could predict the grinding direction. Experimental scratches were placed using a scalpel blade on standardised wear facets that had been prepared by wearing opposing enamel surfaces in an electromechanical tooth wear machine. These control 'baseline' facets (with unworn experimental scratches) were subjected to 50 wear cycles, so that differential microwear could be observed on the leading and trailing edges of the 'final' facets. In Group 1 (n=28), the 'footprint' microwear patterns corresponding to the known grinding direction of specimens in the tooth wear machine were identified. Then, they were used to predict the direction of tooth grinding blindly in the same sample after a 2-week intermission period. To avoid overfitting the predictive model, its sensitivity was also cross-validated in a new sample (Group 2, n=14). A crescent-shaped characteristic observed in most experimental scratches matched the grinding direction on all occasions. The best predictor of the direction of grinding was a combined assessment of the leading edge microwear pattern and the crescent characteristic (82.1% in Group 1 and 92.9% in Group 2). In conclusion, a simple scratch test can determine the direction of tooth grinding with high reliability, although further improvement in sensitivity is desirable. © 2012 Blackwell Publishing Ltd.

The Effect of Wood Alignment on Wood Grinding – Part 1: Properties of Pulp and Fines Revealed in the Grinding Mechanism

Directory of Open Access Journals (Sweden)

Erkki Tapani Saharinen

2016-03-01

Full Text Available In industrial wood grinding, logs are pressed against a rotating stone, with the logs and fiber axis parallel to the axis of the stone. The objective of this study is to clarify how the wood alignment affects the process and pulp properties. In this research, wood blocks were fed into a laboratory grinder with various alignments in relation to the surface of the grinding stone. The effects of the alignment on the properties of the pulp and the amount and quality of fines were measured. A grinding mechanism was proposed. The results show that the pulp quality is very sensitive to the angle between the stone surface and the log. In gentle refining, the fiber structure is loosened by fatigue before it is bent on the surface; pressure pulses produce fibrillar material, and fibers develop toward having good bonding ability. In forced grinding, the process is “violent”, and the fiber wears and becomes crushed immediately on the surface into small particles with low bonding ability.

Thermoluminescence dating of Brazilian indigenous ceramics

International Nuclear Information System (INIS)

Farias, T. M. B.; Gennari, R. F.; Etchevarne, C.; Watanabe, S.

2009-01-01

Two indigenous ceramics fragments, one from Lagoa Queimada (LQ) and another from Barra dos Negros (BN), both sites located on Bahia state (Brazil), were dated by thermoluminescence (TL) method. Each fragment was physically prepared and divided into two fractions, one was used for TL measurement and the other for annual dose determination. The TL fraction was chemically treated, divided in sub samples and irradiated with several doses. The plot extrapolation from TL intensities as function of radiation dose enabled the determination of the accumulated dose (D ac ), 3.99 Gy and 1.88 Gy for LQ and BN, respectively. The annual dose was obtained through the uranium, thorium and potassium determination by ICP-MS. The annual doses (D an) obtained were 2.86 and 2.26 mGy/year. The estimated ages were ∼1375 and 709 y for BN and LQ ceramics, respectively. The ages agreed with the archaeologists' estimation for the Aratu and Tupi tradition periods, respectively. (authors)

Surface topography of parallel grinding process for nonaxisymmetric aspheric lens

International Nuclear Information System (INIS)

Zhang Ningning; Wang Zhenzhong; Pan Ri; Wang Chunjin; Guo Yinbiao

2012-01-01

Workpiece surface profile, texture and roughness can be predicted by modeling the topography of wheel surface and modeling kinematics of grinding process, which compose an important part of precision grinding process theory. Parallel grinding technology is an important method for nonaxisymmetric aspheric lens machining, but there is few report on relevant simulation. In this paper, a simulation method based on parallel grinding for precision machining of aspheric lens is proposed. The method combines modeling the random surface of wheel and modeling the single grain track based on arc wheel contact points. Then, a mathematical algorithm for surface topography is proposed and applied in conditions of different machining parameters. The consistence between the results of simulation and test proves that the algorithm is correct and efficient. (authors)

Investigation of the Formation Process of Two Piracetam Cocrystals during Grinding

Science.gov (United States)

Rehder, Sönke; Klukkert, Marten; Löbmann, Korbinian A. M.; Strachan, Clare J.; Sakmann, Albrecht; Gordon, Keith; Rades, Thomas; Leopold, Claudia S.

2011-01-01

Cocrystal formation rates during dry grinding and liquid-assisted grinding were investigated by X-ray powder diffractometry and Raman spectroscopy. Two polymorphic forms of piracetam were used to prepare known piracetam cocrystals as model substances, i.e., piracetam-citric acid and piracetam-tartaric acid cocrystals. Raman spectroscopy in combination with principal component analysis was used to visualize the cocrystal formation pathways. During dry grinding, cocrystal formation appeared to progress via an amorphous intermediate stage, which was more evident for the piracetam-citric acid than for the piracetam-tartaric acid cocrystal. It was shown that liquid-assisted grinding led to faster cocrystal formation than dry grinding, which may be explained by the higher transformation rate due to the presence of liquid. The cocrystal formation rate did not depend on the applied polymorphic form of the piracetam and no polymorphic cocrystals were obtained. PMID:24309304

Manifestation of Crystal Lattice Distortions in the IR Reflection Spectra of Abrasion-Treated ZnSe Ceramics

Science.gov (United States)

Sitnikova, V. E.; Dunaev, A. A.; Mamalimov, R. I.; Pakhomov, P. M.; Khizhnyak, S. D.; Chmel, A. E.

2017-07-01

The Fourier IR reflection spectra of ZnSe ceramics prepared by hot pressing (HP), physical vapor deposition (PVD), and PVD combined with hot isostatic pressing (HIP) are presented. The optical constants of polished and dry-ground specimens were used for comparison. The grinding treatment simulated the erosion of the outer surface of optical elements made of zinc selenide under the influence of solid dust particles and deposits. In the polished specimens residual stresses showed up in the IR reflection spectra of the ZnSePVD and ZnSeHIP ceramics, which had well-defined orientation of grains, but were not present in the spectra of the ZnSeHIP ceramics as a result of mutual compensation of the stresses in the randomly oriented grains of the material. The stresses, which appeared as a shift of the absorption bands calculated by the Kramers-Kronig method, increased significantly after abrasive treatment of the specimens. For all the treated ceramics the intensity of the absorption bands resulting from the anharmonicity of the vibrations in the distorted crystal lattice increased by several times. The last effect also depends on the production prehistory of the ceramics.

Fine grinding of brittle minerals and materials by jet mill

OpenAIRE

Lek Sikong; Kalayanee Kooptanond; Noparit Morasut; Thammasak Pongprasert

2008-01-01

Various variables affecting grinding, such as air pressure, minerals or materials hardness, feed size were investigated.The limitations of grinding of gypsum, barite, ilmenite, quartz and ferrosilicon were also elucidated by means of particlefineness size distribution and morphology of ground products. It was found that:1) The density of particles, which are in the grinding zone affects the product fineness, i.e. higher feed rate resultsin a larger product size. The appropriate feed rate is s...

Development of Composite Grinding Wheels for Hard and Soft Metals

OpenAIRE

Pruti, Faruk

2012-01-01

This research investigates the performance of grinding wheel in terms of its internal granular particles and their effect on the surface finish for both soft and hard metals subjected to both dry and wet conditions of use. The study considers the properties of materials of construction including hardness of the granular particles and their size and distributions that affects the grinding wheel efficiency in abrading of soft and hard metal surfaces. Furthermore, in order to improve grinding pe...

Research of grinding process of gears with involute profile to increase its efficiency

Science.gov (United States)

Ivanova, T. N.; Korshunov, A. I.; Sannikov, I. N.; Tyukpiekov, V. N.

2018-03-01

Grinding as final processing exerts great influence on quality and accuracy of a surface layer of gears. Gear grinding is the most productive method of abrasive processing providing gears of 3 - 8 degrees of accuracy. However violation of the temperature condition of grinding leads to emergence of burns on the surfaces of gears. Therefore the research of the reasons generating defects and finding the ways of their elimination are relevant. The work presents the research of involute tooth profile grinding by wheels of different types with different ways to form a surface. For every way the movements of a tool and a workpiece in order to receive a contour of the tooth socket are simulated. The advantages and the shortcomings of the tooth grinding using form wheels in a grinding method and using dish, worm wheels in generating the grinding method are revealed. The experience of gear production shows that availability of burns in the certain part of a tooth profile is caused by features of the gear grinding process. Theoretical and experimental researches of the thermal phenomena of gear grinding with different configurations of spots in a contact zone and a trajectory of their movement are conducted. There are recommendations how to choose grinding modes, characteristics of abrasive tools taking into account a non-burnt condition of a working surface of a gear. The right choice of lubricating fluid and the way of its supply greatly affect the efficiency of the gear grinding process. It is established that lubricating fluid with special additives gives the best results to obtain desired roughness of a processed surface. The recommendations of effective fluids and their foreign analogs are made.

Industrial versus Laboratory Clinker Processing Using Grinding Aids (Scale Effect

Directory of Open Access Journals (Sweden)

Joseph Jean Assaad

2015-01-01

Full Text Available The evaluation of grinding aid (GA effect on clinker processing in laboratory grinding mills is relatively simple. Yet, the results obtained cannot be directly transposed to industrial mills, given the fundamentally different operational modes and grinding parameters. This paper seeks to evaluate the scale effect by comparing the results obtained from a closed-circuit tube mill operating at 90 ton/hr to those determined using a 50-liter laboratory mill. Tests results have shown that the decrease in specific energy consumption (Ec due to glycol or amine-based GA can be evaluated under laboratory conditions. However, such tests underestimate the actual performance that could be achieved in real-scale mills; the Ec reduction due to GA is around twofold higher when grinding is performed in real-scale mill. Compared to industrial tests, the cement particle size distribution curves widened and shifted towards higher diameters when grinding was performed under laboratory conditions, particularly with GA additions. This led to remarkable changes in water demand, setting time, and 1- and 28-day compressive strengths.

FOREWORD: Focus on Advanced Ceramics Focus on Advanced Ceramics

Science.gov (United States)

Ohashi, Naoki

2011-06-01

Much research has been devoted recently to developing technologies for renewable energy and improving the efficiency of the processes and devices used in industry and everyday life. Efficient solutions have been found using novel materials such as platinum and palladium-based catalysts for car exhaust systems, samarium-cobalt and neodymium-iron-boron permanent magnets for electrical motors, and so on. However, their realization has resulted in an increasing demand for rare elements and in their deficit, the development of new materials based on more abundant elements and new functionalities of traditional materials. Moreover, increasing environmental and health concerns demand substitution of toxic or hazardous substances with nature-friendly alternatives. In this context, this focus issue on advanced ceramics aims to review current trends in ceramics science and technology. It is related to the International Conference on Science and Technology of Advanced Ceramics (STAC) held annually to discuss the emerging issues in the field of ceramics. An important direction of ceramic science is the collaboration between experimental and theoretical sciences. Recent developments in density functional theory and computer technology have enabled the prediction of physical and chemical properties of ceramics, thereby assisting the design of new materials. Therefore, this focus issue includes articles devoted to theory and advanced characterization techniques. As mentioned above, the potential shortage of rare elements is becoming critical to the industry and has resulted in a Japanese government initiative called the 'Ubiquitous Element Strategy'. This focus issue also includes articles related to this strategy and to the associated topics of energy conversion, such as phosphors for high-efficiency lighting and photocatalysts for solar-energy harvesting. We hope that this focus issue will provide a timely overview of current trends and problems in ceramics science and

Determination of the boundary conditions of the grinding load in ball mills

Science.gov (United States)

Sharapov, Rashid R.

2018-02-01

The prospects of application in ball mills for grinding cement clinker with inclined partitions are shown. It is noted that ball mills with inclined partitions are more effective. An algorithm is proposed for calculating the power consumed by a ball mill with inclined inter-chamber partitions in which an axial movement of the ball load takes place. The boundary conditions in which the ball load is located are determined. The equations of bounding the grinding load are determined. The behavior of a grinding load is considered in view of the characteristic cross sections. The coordinates of the centers of gravity of the grinding load with a definite step and the shape of the cross sections are determined. It is theoretically shown that grinding load in some parts of the ball mill not only consumes, but also helps to rotate the ball mill. Methods for calculating complex analytical expressions for determining the coordinates of the centers of gravity of the grinding load under the conditions of its longitudinal motion have developed. The carried out researches allow to approach from the general positions to research of behavior of a grinding load in the ball mills equipped with various in-mill devices.

Grinding tool for use in a fuel assembly repair and reconstitution system

International Nuclear Information System (INIS)

Tolino, R.W.

1988-01-01

A remotely operable grinding apparatus particularly adapted for abrasively removing a portion of a structure underwater is described comprising a baseplate, a motor means having an output shaft, a grinding head operatively connected to the output shaft, a housing for isolating the motor means from ambient water, guide means slidably connecting the housing to the baseplate for guiding the grinding head to a selected portion of the structure, and means for selectively moving the grinding head against the portion of the structure

A 2-year follow-up of spirometric parameters in workers of a tile and ceramic industry, Yazd, southeastern Iran.

Science.gov (United States)

Mehrparvar, A H; Mirmohammadi, S J; Mostaghaci, M; Davari, M H; Hashemi, S H

2013-04-01

Respiratory diseases cause a considerable amount of morbidity and mortality in the world. Pulmonary function tests are important measures for the diagnosis and management of respiratory disorders. Workers in tile and ceramic industry are exposed to high amounts of respiratory pollutants. To identify the changes in spirometric parameters in a 2-year period among tile and ceramic workers in Yazd and compare it with a control group. The study was conducted in 5 tile and ceramic factories selected by cluster sampling between 2009 and 2011 in Yazd, southeastern Iran. Demographic data and spirometric parameters of participants were recorded. Spirometric parameters were significantly reduced during the 2 years. The largest decrease was observed in FVC (≈500 mL) in ball-mill and grinding after 2 years. Decrease in all spirometric parameters was significantly higher in industrial workers than office workers. Respiratory exposure in tile and ceramic industry can significantly affect pulmonary function tests.

Thermal model to investigate the temperature in bone grinding for skull base neurosurgery.

Science.gov (United States)

Zhang, Lihui; Tai, Bruce L; Wang, Guangjun; Zhang, Kuibang; Sullivan, Stephen; Shih, Albert J

2013-10-01

This study develops a thermal model utilizing the inverse heat transfer method (IHTM) to investigate the bone grinding temperature created by a spherical diamond tool used for skull base neurosurgery. Bone grinding is a critical procedure in the expanded endonasal approach to remove the cranial bone and access to the skull base tumor via nasal corridor. The heat is generated during grinding and could damage the nerve or coagulate the blood in the carotid artery adjacent to the bone. The finite element analysis is adopted to investigate the grinding-induced bone temperature rise. The heat source distribution is defined by the thermal model, and the temperature distribution is solved using the IHTM with experimental inputs. Grinding experiments were conducted on a bovine cortical bone with embedded thermocouples. Results show significant temperature rise in bone grinding. Using 50°C as the threshold, the thermal injury can propagate about 3mm in the traverse direction, and 3mm below the ground surface under the dry grinding condition. The presented methodology demonstrated the capability of being a thermal analysis tool for bone grinding study. Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.

Temperature prediction in high speed bone grinding using motor PWM signal.

Science.gov (United States)

Tai, Bruce L; Zhang, Lihui; Wang, Anthony C; Sullivan, Stephen; Wang, Guangjun; Shih, Albert J

2013-10-01

This research explores the feasibility of using motor electrical feedback to estimate temperature rise during a surgical bone grinding procedure. High-speed bone grinding is often used during skull base neurosurgery to remove cranial bone and approach skull base tumors through the nasal corridor. Grinding-induced heat could propagate and potentially injure surrounding nerves and arteries, and therefore, predicting the temperature in the grinding region would benefit neurosurgeons during the operation. High-speed electric motors are controlled by pulse-width-modulation (PWM) to alter the current input and thus maintain the rotational speed. Assuming full mechanical to thermal power conversion in the grinding process, PWM can be used as feedback for heat generation and temperature prediction. In this study, the conversion model was established from experiments under a variety of grinding conditions and an inverse heat transfer method to determine heat flux. Given a constant rotational speed, the heat conversion was represented by a linear function, and could predict temperature from the experimental data with less than 20% errors. Such results support the advance of this technology for practical application. Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.

Work Index and Grinding Energy Assessment of Dilband Iron Ore, Pakistan

Directory of Open Access Journals (Sweden)

Muhammad Ishaque Abro

2011-01-01

Full Text Available Importance of comminution in mineral processing sector is highly acknowledged from energy perspective. In present study an attempt was made to understand the comminuting behavior of Dilband iron ore and to compute the grinding energy requirement for production of ultrafine particles up to mesh of liberation. In this regard standard grindability tests developed by the Chair of Mineral Processing Leoben Austria was used for calculating work index of Dilband iron ore. The grinding tests were conducted in rod and ball mills. The work index value of two feed size fractions with 80% passing at 3800?m and 5200?m was noted to be 11.85 kwh/t and 9.3 kwh/ton respectively. Ball mill grinding test indicates that dry grinding in open circuit is not efficient and consumes more energy of 88.48kwh/t of ore for grinding 1000/40?m to 80% <40?m size.

Investigation of the Formation Process of Two Piracetam Cocrystals during Grinding

Directory of Open Access Journals (Sweden)

Keith Gordon

2011-10-01

Full Text Available Cocrystal formation rates during dry grinding and liquid-assisted grinding were investigated by X-ray powder diffractometry and Raman spectroscopy. Two polymorphic forms of piracetam were used to prepare known piracetam cocrystals as model substances, i.e.,piracetam-citric acid and piracetam-tartaric acid cocrystals. Raman spectroscopy in combination with principal component analysis was used to visualize the cocrystal formation pathways. During dry grinding, cocrystal formation appeared to progress via an amorphous intermediate stage, which was more evident for the piracetam-citric acid than for the piracetam-tartaric acid cocrystal. It was shown that liquid-assisted grinding led to faster cocrystal formation than dry grinding, which may be explained by the higher transformation rate due to the presence of liquid. The cocrystal formation rate did not depend on the applied polymorphic form of the piracetam and no polymorphic cocrystals were obtained.

Science and Technology of Ceramics -4 ...

Indian Academy of Sciences (India)

In order to improve the mechanical properties of these ceramics other materials are ... temperature range of 800 to 1650 °C. SiC fiber reinforced SiC composite is .... (X= S, Se, Te) system where it is possible to get an n-type semi- conductor by ...

Lab-scale roller table mill for investigating the grinding behaviour of coal

Energy Technology Data Exchange (ETDEWEB)

Werner, V.; Zelkowski, J.; Schoenert, K. [Inst. for Energy Process Engineering and Fuel Technology and Inst. of Mineral Processing, Univ. Clausthal, Clausthal-Zellerfeld (Germany)

1999-11-01

The test mill is equipped with one roller. The material bed can be discharged completely after overroling. Grinding force, torque and gap width are measured. Cycle tests with three coals have been performed for simulating a closed circuit process. The grinding behaviour is characterized by the following relations: compaction of the particle bed and specific power draft vs. specific grinding force, production of fine material (dust), circuit factor, specific surface of the dust and specific work-input of the grinding circuit vs. specific power draft. (orig.)

Grinding patterns in migraine patients with sleep bruxism: a case-controlled study.

Science.gov (United States)

Kato, Momoko; Saruta, Juri; Takeuchi, Mifumi; Sugimoto, Masahiro; Kamata, Yohei; Shimizu, Tomoko; To, Masahiro; Fuchida, Shinya; Igarashi, Hisaka; Kawata, Toshitsugu; Tsukinoki, Keiichi

2016-11-01

Details on grinding patterns and types of contact during sleep bruxism in association with migraine headache have not yet been elucidated. This study compared the characteristics of sleep bruxism between patients with migraine and controls. The study included 80 female patients who had been diagnosed with migraine and 52 women with no history of migraine. Grinding patterns were measured using the BruxChecker® (Scheu Dental, Iserlohn, Germany). There was a significant difference between the two groups in the distribution of grinding patterns at the laterotrusive side (p grinding area at all sites was significantly larger in the migraine group than in the control group (p grinding over a large area among migraine patients, particularly in the molar region.

FY 1998 annual report on the development of laser-aided, noncontacting, realtime, in-process dressing method using a grinding stone with ultrafine abrasive grains, and study on techniques for applying the method to grinding stone of superthin blades; 1998 nendo laser wo mochiita choteiryu toishi no hisesshoku real time inprocess dressing ho no kaihatsu oyobi gokuusuha toishi eno tekiyo gijutsu ni kansuru kenkyu chosa hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-03-01

A new noncontacting dressing method using a laser as a tool has been studied and developed, in order to develop environment-compatible, energy-saving type machining machines. In this study, a cup-shaped grinding stone is developed for grinding performance testing by micron-order diamond abrasive powder, used for producing a grinding stone of superthin blades, is mixed with a cast iron binder, molded and sintered. In the grinding performance test, zirconia as a work is ground at a constant pressure to the grinding stone working surface before and after the laser-aided dressing, to analyze grinding/removal efficiency and grinding resistance. The grinding stone working surface conditions are observed by a scanning electron microscope after the laser-aided dressing, to correlate the surface conditions with the grinding data. It is found that the laser-aided dressing method needs no lubricant, is clean, cutting grinding time when incorporated in the machining process, suitable for grinding stone of low stiffness and ultrathin blades by use of ultrafine abrasive grains, suffering no exfoliation of the diamond grains, and hence economical. (NEDO)

For production of ceramic plates coating using waste kaolin, granite and marble; Caracterizacao de residuos de caulim, granito e marmore para uso em massas ceramicas

Energy Technology Data Exchange (ETDEWEB)

Sales, J.L.; Morais, C.R.S.; Lima, L.M.R.; Altidis, M.E.D., E-mail: josyanne27@yahoo.com.br [Universidade Federal de Campina Grande (UFCG), PB (Brazil)

2011-07-01

The objective is to benefit and characterize waste from kaolin, marble and granite studying their thermal properties and spectroscopic in employment perspective on ceramic production of flooring boards. The residues were benefited through the process of dry grinding mill in greyhounds and passed through sieve 0.074 mm (ABNT No. 200), observing their suitability for the formulation of ceramic pastes. Tests were performed physicochemical characterization (particle size analysis, X-ray fluorescence and X-ray diffraction) and thermal (differential thermal analysis and thermogravimetry). The results showed that these residues showed satisfactory properties for the purpose for which it proposes, and contribute to reducing environmental impacts, allowing the reuse of the production of ceramic plates (author)

Investigation of the Formation Process of Two Piracetam Cocrystals during Grinding

OpenAIRE

Rehder, Sönke; Klukkert, Marten; Löbmann, Korbinian A. M.; Strachan, Clare J.; Sakmann, Albrecht; Gordon, Keith; Rades, Thomas; Leopold, Claudia S.

2011-01-01

Cocrystal formation rates during dry grinding and liquid-assisted grinding were investigated by X-ray powder diffractometry and Raman spectroscopy. Two polymorphic forms of piracetam were used to prepare known piracetam cocrystals as model substances, i.e., piracetam-citric acid and piracetam-tartaric acid cocrystals. Raman spectroscopy in combination with principal component analysis was used to visualize the cocrystal formation pathways. During dry grinding, cocrystal formation appeared to ...

Interproximal grinding (disking) of caries in primary molars, attitudes and the extent utilized in a Swedish County.

Science.gov (United States)

Granath, Johanna; Asztély, Anna; Lundgren, Ted

2018-04-30

To assess the occurrence of interproximal grinding as a caries therapy in primary molars, to what degree grinding replaced conventional restorative caries therapy, to what extent anaesthesia was used while grinding and to assess open comments about attitudes about grinding. A questionnaire was sent to 108 public dental service clinics with questions concerning the use of grinding as a therapy and alternative to restorative treatment, the use of anaesthesia prior to conventional caries therapy and grinding, respectively. In addition, a content analysis of open comments about grinding was performed. Grinding had been performed in 96% of the clinics. Two-thirds of the dentists used grinding as an alternative to conventional restorative treatment at some point. Most dentists used anaesthesia prior to restorative therapy. Prior to grinding, the frequency of anaesthesia was lower (median 5.0) than for conventional restorative therapy (median 8.7) (p grinding. Grinding has been widely practiced in parts of Sweden, is presently a technique employed by a multitude of dentists, and that anaesthesia is used less frequently prior to grinding, in comparison to conventional restorative therapy. Dentist considered grinding as a treatment option in specific situations.

Grinding performance evaluation of porous composite-bonded CBN wheels for Inconel 718

Directory of Open Access Journals (Sweden)

Chen Zhenzhen

2014-08-01

Full Text Available For high-efficiency grinding of difficult-to-cut materials such as titanium and nickel alloys, a high porosity is expected and also a sufficient mechanical strength to satisfy the function. However, the porosity increase is a disadvantage to the mechanical strength. As a promising pore forming agent, alumina bubbles are firstly induced into the abrasive layer to fabricate porous cubic boron nitride (CBN wheels. When the wheel porosity reaches 45%, the bending strength is still high up to 50 MPa with modified orderly pore distribution. A porous CBN wheel was fabricated with a total porosity around 30%. The grinding performance of the porous composite-bonded CBN wheel was evaluated in terms of specific force, specific grinding energy, and grinding temperature, which were better than those of the vitrified one under the same grinding conditions. Compared to the vitrified CBN wheel, clear straight cutting grooves and less chip adhesion are observed on the ground surface and there is also no extensive loading on the wheel surface after grinding.

Analysis and Compensation for Gear Accuracy with Setting Error in Form Grinding

Directory of Open Access Journals (Sweden)

Chenggang Fang

2015-01-01

Full Text Available In the process of form grinding, gear setting error was the main factor that influenced the form grinding accuracy; we proposed an effective method to improve form grinding accuracy that corrected the error by controlling the machine operations. Based on establishing the geometry model of form grinding and representing the gear setting errors as homogeneous coordinate, tooth mathematic model was obtained and simplified under the gear setting error. Then, according to the gear standard of ISO1328-1: 1997 and the ANSI/AGMA 2015-1-A01: 2002, the relationship was investigated by changing the gear setting errors with respect to tooth profile deviation, helix deviation, and cumulative pitch deviation, respectively, under the condition of gear eccentricity error, gear inclination error, and gear resultant error. An error compensation method was proposed based on solving sensitivity coefficient matrix of setting error in a five-axis CNC form grinding machine; simulation and experimental results demonstrated that the method can effectively correct the gear setting error, as well as further improving the forming grinding accuracy.

The grinding behavior of ground copper powder for Cu/CNT nanocomposite fabrication by using the dry grinding process with a high-speed planetary ball mill

Science.gov (United States)

Choi, Heekyu; Bor, Amgalan; Sakuragi, Shiori; Lee, Jehyun; Lim, Hyung-Tae

2016-01-01

The behavior of ground copper powder for copper-carbon nanotube (copper-CNT) nanocomposite fabrication during high-speed planetary ball milling was investigated because the study of the behavior characteristics of copper powder has recently gained scientific interest. Also, studies of Cu/CNT composites have widely been done due to their useful applications to enhanced, advanced nano materials and components, which would significantly improve the properties of new mechatronics-integrated materials and components. This study varied experimental conditions such as the rotation speed and the grinding time with and without CNTs, and the particle size distribution, median diameter, crystal structure and size, and particle morphology were monitored for a given grinding time. We observed that pure copper powders agglomerated and that the morphology changed with changing rotation speed. The particle agglomerations were observed with maximum experiment conditions (700 rpm, 60 min) in this study of the grinding process for mechanical alloys in the case of pure copper powders because the grinding behavior of Cu/CNT agglomerations was affected by the addition of CNTs. Indeed, the powder morphology and the crystal size of the composite powder could be changed by increasing the grinding time and the rotation speed.

Association between anticonvulsant drugs and teeth-grinding in children and adolescents with cerebral palsy.

Science.gov (United States)

Ortega, A O L; Dos Santos, M T B R; Mendes, F M; Ciamponi, A L

2014-09-01

The relation between teeth-grinding and the use of drugs acting on the central nervous system of cerebral palsy (CP) patients has not yet been described. The aim of this research was to evaluate the presence or absence of teeth-grinding (sleep and/or awake periods) in normal and in CP children and adolescents, as well as the association of teeth-grinding and use of anticonvulsant drugs. The sample consisted of 207 children and adolescents, divided into three groups: G1, individuals with CP who did not take anticonvulsant drugs; G2, individuals with CP administered medications on a regular basis; and CG, normal individuals. Logistic regression analyses were performed to evaluate the association of teeth-grinding with some variables. No significant statistical differences were observed regarding the presence or absence of teeth-grinding when G1 and G2 were compared. However, compared with the CG, a statistically significant difference was determined, with the CG showing fewer children presenting teeth-grinding (P grinding. CP children and adolescents show a greater and significant presence of grinding of the teeth compared with normal individuals. Subjects taking barbiturate drugs showed greater presence of teeth-grinding, than those who were taking medications from the other groups of anticonvulsant drugs. © 2014 John Wiley & Sons Ltd.

Annual report 1985

International Nuclear Information System (INIS)

1985-01-01

Aspects regarding ceramics, electronic materials, metals, the specialist task group, services to industry and other organizations and research support activities are discussed in the report. The highlights of the period are given, namely: the effect of high pressure on twophase systems, spinel structures, elastic moduli of stabilized zirconia crystals, alumina ceramics, a fast sodium-ion conducting solid electrolyte (Nasicon), liquid phase epitaxial growth of (HgCd)Te, compositional uniformity of bulk-grown (HgCd)Te, semi-quantitative mass spectrography of Cd and Te, depth profiling of metal semiconductor interdiffusion, low resistance ohmic contacts on GaAs, studies of Fe-Mn-Al alloys, surface mechanical properties of materials, electron diffraction, ceramic mould laboratory for investment casting of metals, grain boundary, sliding in the deformation of polycrystalline copper and a theory of work-hardening in face-centered cubic metals

Grinding, Machining Morphological Studies on C/SiC Composites

Science.gov (United States)

Xiao, Chun-fang; Han, Bing

2018-05-01

C/SiC composite is a typical material difficult to machine. It is hard and brittle. In machining, the cutting force is large, the material removal rate is low, the edge is prone to collapse, and the tool wear is serious. In this paper, the grinding of C/Si composites material along the direction of fiber distribution is studied respectively. The surface microstructure and mechanical properties of C/SiC composites processed by ultrasonic machining were evaluated. The change of surface quality with the change of processing parameters has also been studied. By comparing the performances of conventional grinding and ultrasonic grinding, the surface roughness and functional characteristics of the material can be improved by optimizing the processing parameters.

Grind hardening process

CERN Document Server

Salonitis, Konstantinos

2015-01-01

This book presents the grind-hardening process and the main studies published since it was introduced in 1990s.  The modelling of the various aspects of the process, such as the process forces, temperature profile developed, hardness profiles, residual stresses etc. are described in detail. The book is of interest to the research community working with mathematical modeling and optimization of manufacturing processes.

An experimental assessment on the performance of different lubrication techniques in grinding of Inconel 751.

Science.gov (United States)

Balan, A S S; Vijayaraghavan, L; Krishnamurthy, R; Kuppan, P; Oyyaravelu, R

2016-09-01

The application of emulsion for combined heat extraction and lubrication requires continuous monitoring of the quality of emulsion to sustain a desired grinding environment; this is applicable to other grinding fluids as well. Thus to sustain a controlled grinding environment, it is necessary to adopt an effectively lubricated wheel-work interface. The current study was undertaken to assess experimentally the ​ effects of different grinding environments such as dry, minimum quantity lubrication (MQL) and Cryo-MQL on performance, such as grinding force, temperature, surface roughness and chip morphology on Inconel 751, a higher heat resistance material posing thermal problems and wheel loading. The results show that grinding with the combination of both liquid nitrogen (LN2) and MQL lowers temperature, cutting forces, and surface roughness as compared with MQL and dry grinding. Specific cutting energy is widely used as an inverse measure of process efficiency in machining. It is found from the results that specific cutting energy of Cryo-MQL assisted grinding is 50-65% lower than conventional dry grinding. The grindability of Inconel 751 superalloy can be enhanced with Cryo-MQL condition.

TL sensitivity of CaSO4:Dy phosphor powder - effect of grinding

International Nuclear Information System (INIS)

Shastry, S.S.; Kher, R.K.

1979-01-01

Grinding of polycrystalline CaSO 4 :Dy phosphor to powder form induces lattice defects. Changes in thermoluminescence (TL) sensitivity due to variation in trap density in the bulk and on the surface of phosphor grains are studied using gamma and UV radiations. TL sensitivity to gamma increases with grinding time due to the contribution from the new bulk traps which are generated by grinding. The surface traps degrade with increase in grinding time resulting in a decrease in UV sensitivity. Results on regeneration of the TL sensitivity due to annealing at different temperatures are also included. (Auth.)

Imaging subsurface damage of grinded fused silica optics by confocal fluorescence microscopy

International Nuclear Information System (INIS)

Neauport, J.; Cormont, P.; Destribats, J.; Legros, P.; Ambard, C.

2009-01-01

We report an experimental investigation of fluorescence confocal microscopy as a tool to measure subsurface damage on grinded fused silica optics. Confocal fluorescence microscopy was performed with an excitation at the wavelength of 405 nm on fixed abrasive diamond grinded fused silica samples. We detail the measured fluorescence spectrums and compare them to those of oil based coolants and grinding slurries. We evidence that oil based coolant used in diamond grinding induces a fluorescence that marks the subsurface damages and eases its observation. Such residual traces might also be involved in the laser damage process. (authors)

Experiment research on grind-hardening of AISI5140 steel based on thermal copensation

Energy Technology Data Exchange (ETDEWEB)

Huang, Xiang Ming; Ren, Ying Hui; Zheng, Bo; Zhou, Zhixiong [College of Mechanical and Vehicle Engineering, Hunan University, Changsha, Hunan (China); Deng, Zhao Hui [Key Laboratory for High Efficiency and Precision Machining of Difficult-to-Cut Material of Hunan Province, Hunan (China)

2016-08-15

The grind-hardening process utilizes the heat generated to induce martensitic phase transformation. However, the maximum achievable harden layer depth is limited due to high grinding forces, and the tensile residual stress appears on the ground surface in the grind-hardening process. This paper proposes a new grind-hardening technology using thermal compensation. The workpiece of AISI5140 steel is preheated by electric resistance heating, and ground under the condition of the workpiece temperature 25°C, 120°C, 180°C and 240°C. The grinding force, harden layer depth and surface quality including residual stress on ground surface, surface roughness and micro-hardness are investigated. The experimental results show that a deep harden layer with a fine grain martensite can be obtained with the thermal compensation. The ground workpiece surface produces a certain compressive residual stress, and the residual compressive stress value increases with preheating temperature. As the preheating temperature increases, grinding force slightly decreases, while there is slightly increment of surface roughness. Compared with the conventional grind-hardening process, both the harden layer depth and residual stress distribution are significantly improved.

Processing equipment for grinding of building powders

Science.gov (United States)

Fediuk, R. S.; Ibragimov, R. A.; Lesovik, V. S.; Pak, A. A.; Krylov, V. V.; Poleschuk, M. M.; Stoyushko, N. Y.; Gladkova, N. A.

2018-03-01

In the article questions of mechanical grinding up to nanosize of building powder materials are considered. In the process of mechanoactivation of the composite binder, active molecules of cement minerals arise when molecular packets are destroyed in the areas of defects and loosening of the metastable phase during decompensation of intermolecular forces. The process is accompanied by a change in the kinetics of hardening Portland cement. Mechanical processes in the grinding of mineral materials cause, together with an increase in their surface energy, the growth of the isobaric potential of the powders and, accordingly, their chemical activity, which also contributes to high adhesion strength when they come into contact with binders. Thus, a set of measures for mechanical activation allows more fully use the mass of components of the filled cement systems and regulate their properties. At relatively low costs, it is possible to provide an impressive and, importantly, easily repeatable in production conditions result. It is revealed that the use of a vario-planetary mill allows to achieve the best results on grinding the powder building materials.

Teeth grinding, oral motor performance and maximal bite force in cerebral palsy children.

Science.gov (United States)

Botti Rodrigues Santos, Maria Teresa; Duarte Ferreira, Maria Cristina; de Oliveira Guaré, Renata; Guimarães, Antonio Sergio; Lira Ortega, Adriana

2015-01-01

Identify whether the degree of oral motor performance is related to the presence of teeth grinding and maximal bite force values in children with spastic cerebral palsy. Ninety-five spastic cerebral palsy children with and without teeth grinding, according to caregivers' reports, were submitted to a comprehensive oral motor performance evaluation during the feeding process using the Oral Motor Assessment Scale. Maximal bite force was measured using an electronic gnathodynamometer. The teeth grinding group (n = 42) was younger, used anticonvulsant drugs, and was more frequently classified within the subfunctional oral motor performance category. Teeth grinding subfunctional spastic cerebral palsy children presented lower values of maximal bite force. The functional groups showing the presence or absence of teeth grinding presented higher values of maximal bite force compared with the subfunctional groups. In spastic cerebral palsy children, teeth grinding is associated with the worse oral motor performance. © 2015 Special Care Dentistry Association and Wiley Periodicals, Inc.

Polishing of silicon based advanced ceramics

Science.gov (United States)

Klocke, Fritz; Dambon, Olaf; Zunke, Richard; Waechter, D.

2009-05-01

Silicon based advanced ceramics show advantages in comparison to other materials due to their extreme hardness, wear and creep resistance, low density and low coefficient of thermal expansion. As a matter of course, machining requires high efforts. In order to reach demanded low roughness for optical or tribological applications a defect free surface is indispensable. In this paper, polishing of silicon nitride and silicon carbide is investigated. The objective is to elaborate scientific understanding of the process interactions. Based on this knowledge, the optimization of removal rate, surface quality and form accuracy can be realized. For this purpose, fundamental investigations of polishing silicon based ceramics are undertaken and evaluated. Former scientific publications discuss removal mechanisms and wear behavior, but the scientific insight is mainly based on investigations in grinding and lapping. The removal mechanisms in polishing are not fully understood due to complexity of interactions. The role of, e.g., process parameters, slurry and abrasives, and their influence on the output parameters is still uncertain. Extensive technological investigations demonstrate the influence of the polishing system and the machining parameters on the stability and the reproducibility. It is shown that the interactions between the advanced ceramics and the polishing systems is of great relevance. Depending on the kind of slurry and polishing agent the material removal mechanisms differ. The observed effects can be explained by dominating mechanical or chemo-mechanical removal mechanisms. Therefore, hypotheses to state adequate explanations are presented and validated by advanced metrology devices, such as SEM, AFM and TEM.

Effect of the bur grit size on the flexural strength of a glass-ceramic

Directory of Open Access Journals (Sweden)

P. P. Kist

Full Text Available Abstract The purpose of the present study was to determine the biaxial flexural strength (BFS of a CAD/CAM leucite reinforced glass-ceramic ground by diamond burs of different grit sizes and the influence of surface roughness on the BFS. For this, 104 plates were obtained from CAD/CAM ceramic blocks and divided into 4 groups (n = 26, according to bur grit size: extra-fine, fine, medium and coarse. Roughness parameters (Ra, RyMax were measured, and plates were kept dry for 7 days. The flexural test was carried out and BFS was calculated. Ra, RyMax and BFS data were subjected to analysis of variance and post-hoc test. Weibull analysis was used to compare characteristic strength and Weibull modulus. Regression analysis was performed for BFS vs. Ra and RyMax. When burs with coarse grit were used, higher surface roughness values were found, causing a negative effect on the ceramic BFS (117 MPa for extra-fine, and 83 MPa for coarse. Correlation (r between surface roughness and BFS was 0.78 for RyMax and 0.73 for Ra. Increases in diamond grit size have a significant negative effect on the BFS of leucite-reinforced glass-ceramics, suggesting that grinding of sintered glass-ceramic should be performed using burs with the finest grit possible in order to minimize internal surface flaws and maximize flexural strength.

Surface crack formation on rails at grinding induced martensite white etching layers

DEFF Research Database (Denmark)

Rasmussen, Carsten Jørn; Fæster, Søren; Dhar, Somrita

2017-01-01

The connection between profile grinding of rails, martensite surface layers and crack initiation has been investigated using visual inspection, optical microscopy and 3D X-ray computerized tomography. Newly grinded rails were extracted and found to be covered by a continuous surface layer...... of martensite with varying thickness formed by the grinding process. Worn R350HT and R200 rails were extracted from the Danish rail network as they had transverse bands resembling grinding marks on the running surface. The transverse bands were shown to consist of martensite which had extensive crack formation...... at the martensite/pearlite interface. The cracks in R350HT propagated down into the rail while those in the soft R200 returned to the surface causing only very small shallow spallation. The transverse bands had the same shape, size, orientation, location and periodicity which would be expected from grinding marks...

Sintering behavior of LZSA glass-ceramics

Directory of Open Access Journals (Sweden)

Oscar Rubem Klegues Montedo

2009-06-01

Full Text Available The LZSA glass-ceramic system (Li2O-ZrO2-SiO2-Al2O 3 shows interesting properties, such as good chemical resistance, low thermal expansion, high abrasion resistance, and a low dielectric constant. However, in order to obtain a high performance material for specific applications, the sintering behavior must be better understood so that the porosity may be reduced and other properties improved. In this context, a sintering investigation for a specific LZSA glass-ceramic system composition was carried out. A 18.8Li2O-8.3ZrO2-64.2SiO2-8.7Al 2O3 glass was prepared by melting the solids, quenching the melt in water, and grinding the resulting solid in order to obtain a powder (3.68 μm average particle diameter. Subsequently, the glass powder was characterized (chemical analysis and determination of thermal properties and the sintering behavior was investigated using optical non-contact dilatometry measurements. The results showed that the crystallization process strongly reduced the sintering in the temperature interval from 785 to 940 °C, and a maximum thermal shrinkage of 15.4% was obtained with operating conditions of 1020 °C and 180 minutes.

An experimental assessment on the performance of different lubrication techniques in grinding of Inconel 751

Directory of Open Access Journals (Sweden)

A.S.S. Balan

2016-09-01

Full Text Available The application of emulsion for combined heat extraction and lubrication requires continuous monitoring of the quality of emulsion to sustain a desired grinding environment; this is applicable to other grinding fluids as well. Thus to sustain a controlled grinding environment, it is necessary to adopt an effectively lubricated wheel-work interface. The current study was undertaken to assess experimentally the ​ effects of different grinding environments such as dry, minimum quantity lubrication (MQL and Cryo-MQL on performance, such as grinding force, temperature, surface roughness and chip morphology on Inconel 751, a higher heat resistance material posing thermal problems and wheel loading. The results show that grinding with the combination of both liquid nitrogen (LN2 and MQL lowers temperature, cutting forces, and surface roughness as compared with MQL and dry grinding. Specific cutting energy is widely used as an inverse measure of process efficiency in machining. It is found from the results that specific cutting energy of Cryo-MQL assisted grinding is 50–65% lower than conventional dry grinding. The grindability of Inconel 751 superalloy can be enhanced with Cryo-MQL condition.

Hot impact densification (HID) - a new method of producing ceramic nuclear fuel pellets with tight dimensional tolerances

International Nuclear Information System (INIS)

Hrovat, M.; Rachor, L.; Muehling, G.; Vollath, D.; Zimmermann, H.

1984-01-01

The hot impact densification (HID) is a new powerful method for producing ceramic fuel pellets for nuclear reactors. Green ceramic bodies are directly processed to pellets by high speed shaping in the plastic temperature region of ceramic material. Opposed to the well established press sintering procedure it can be heated, densified, and cooled by orders of magnitude faster. Therefore, at high throughputs, small equipment dimensions become possible. The fuel pellets produced meet all requirements, particular the dimensional tolerances achieved are very closed, consequently circular grinding is omitted. Furthermore, the relatively high temperature level of the impact pressing favors the mixed crystal formation of uranium and plutonium oxide. This improves the solubility of the fuel in nitric acid, an essential point at reprocessing. A prototype facility is designed so that automatic fabrication in continuous operation will be possible. The target working cycle for a fuel pellet is in the range of some seconds. (orig.)

Grinding efficiency improvement of hydraulic cylinders parts for mining equipment

Directory of Open Access Journals (Sweden)

Korotkov Aleksandr

2017-01-01

Full Text Available The aim of the article is to find out ways to improve parts treatment and components of mining equipment on the example of hydraulic cylinders parts, used as pillars for mine roof supports, and other actuator mechanisms. In the course of the research work methods of machine retaining devices design were used, the scientific approaches for the selection of progressive grinding schemes were applied; theoretical and practical experience in the design and production of new constructions of grinding tools was used. As a result of this work it became possible to create a progressive construction of a machine retaining device for grinding of large parts of hydraulic cylinders, to apply an effective scheme of rotary abrasive treatment, to create and implement new design of grinding tools by means of grains with controllable shape and orientation. Implementation of the results obtained in practice will improve the quality and performance of repairing and manufacturing of mining equipment.

Technological support of tool wear resistant qualities and cost saving of process of planetary grinding of flat parts

Science.gov (United States)

Ivanova, T. N.; Lyupa, D. C.; Revenko, N. F.; Berkutova, T. A.; Silivanova, O. A.

2018-03-01

A lot of factors varied in time lead to instability of the grinding process. Besides, the method of grinding influences significantly the productivity and quality of processing. In this regard a creation of processes of intensive defect-free grinding on the basis of new constructive and technology solutions represents the scientific problem which is of great importance. One of such solutions is application of planetary face grinding which allows simultaneously changing the kinematics of movement, implementing discontinuous grinding. The distinctive features of such grinding are decreasing the heat release rate in a contact zone; ensuring intermittence of the process with a solid grinding wheel; reverse grinding; cutting by different edges of an abrasive grain; stabilization of working parameters of a grinding wheel; ensuring work of a grinding wheel in a self-sharpening mode. The design of the planetary grinding tool was developed for plane surface processing for implementation of the specified distinctive features of planetary grinding. The kinematics of shaping a surface by flat face diamond grinding has been investigated; manufacturing capabilities of planetary face grinding have been revealed, and ways of improvement of quality and productivity have been offered. The algorithm and the program to define the motion path of a grain depending on the given set of grinding factors were received. Optimization of the process of face diamond grinding using the planetary grinding device has been confirmed with the developed program and techniques to choose cutting conditions of planetary grinding and characteristics of grinding wheels for processing different materials. While studying the process of planetary grinding, special attention was paid to the research how processing conditions influence microgeometry of the processed surface made of steel 4X5M (Russian State Standard (GOST)). As a result of the executed research, it was established that surface roughness

Nano finish grinding of brittle materials using electrolytic in-process ...

Indian Academy of Sciences (India)

2016-08-26

Aug 26, 2016 ... Recent developments in grinding have opened up new avenues for finishing of hard and brittle materials with nano-surface finish, high tolerance and accuracy. Grinding with superabrasive wheels is an excellent way to produce ultraprecision surface finish. However, superabrasive diamond grits need ...

Contact and Non-contact Measurements of Grinding Pins

Directory of Open Access Journals (Sweden)

Magdziak Marek

2015-01-01

Full Text Available The paper presents the results of contact and non-contact measurements of external profiles of selected grinding pins. The measurements were conducted in order to choose the appropriate measuring technique in the case of the considered measurement task. In the case of contact measurements the coordinate measuring machine ACCURA II was applied. The used coordinate measuring machine was equipped with the contact scanning probe VAST XT and the Calypso inspection software. Contact coordinate measurements were performed by using of different measurement strategies. The applied strategies included different scanning velocities and distances between measured points. Non-contact measurements were conducted by means of the tool presetter produced by the Mahr company. On the basis of gained results the guidelines concerning measurements of grinding pins were formulated. The measurements of analyzed grinding pins performed by means of the non-contact measuring system are characterized by higher reproducibility than the contact measurements. The low reproducibility of contact measurements may be connected with the inaccuracy of the selected coordinate measuring machine and the measuring probe, the measurement parameters and environmental conditions in the laboratory where the coordinate measuring machine is located. Moreover, the paper presents the possible application of results of conducted investigations. The results of non-contact measurements can be used in the simulation studies of grinding processes. The simulations may reduce the costs of machining processes.

Numerical Simulation of a Grinding Process Model for the Spatial Work-pieces: Development of Modeling Techniques

Directory of Open Access Journals (Sweden)

S. A. Voronov

2015-01-01

Full Text Available The article presents a literature review in simulation of grinding processes. It takes into consideration the statistical, energy based, and imitation approaches to simulation of grinding forces. Main stages of interaction between abrasive grains and machined surface are shown. The article describes main approaches to the geometry modeling of forming new surfaces when grinding. The review of approaches to the chip and pile up effect numerical modeling is shown. Advantages and disadvantages of grain-to-surface interaction by means of finite element method and molecular dynamics method are considered. The article points out that it is necessary to take into consideration the system dynamics and its effect on the finished surface. Structure of the complex imitation model of grinding process dynamics for flexible work-pieces with spatial surface geometry is proposed from the literature review. The proposed model of spatial grinding includes the model of work-piece dynamics, model of grinding wheel dynamics, phenomenological model of grinding forces based on 3D geometry modeling algorithm. Model gives the following results for spatial grinding process: vibration of machining part and grinding wheel, machined surface geometry, static deflection of the surface and grinding forces under various cutting conditions.

Novel CNC Grinding Process Control for Nanometric Surface Roughness for Aspheric Space Optical Surfaces

Directory of Open Access Journals (Sweden)

Jeong-Yeol Han

2004-06-01

Full Text Available Optics fabrication process for precision space optical parts includes bound abrasive grinding, loose abrasive lapping and polishing. The traditional bound abrasive grinding with bronze bond cupped diamond wheel leaves the machine marks of about 20 μm rms in height and the subsurface damage of about 1 μm rms in height to be removed by subsequent loose abrasive lapping. We explored an efficient quantitative control of precision CNC grinding. The machining parameters such as grain size, work-piece rotation speed and feed rate were altered while grinding the work-piece surfaces of 20-100 mm in diameter. The input grinding variables and the resulting surface quality data were used to build grinding prediction models using empirical and multi-variable regression analysis. The effectiveness of such grinding prediction models was then examined by running a series of precision CNC grinding operation with a set of controlled input variables and predicted output surface quality indicators. The experiment achieved the predictability down to ±20 nm in height and the surface roughness down to 36 nm in height. This study contributed to improvement of the process efficiency reaching directly the polishing and figuring process without the need for the loose abrasive lapping stage.

Effect of Grinding on the Solid-State Stability and Particle Dissolution of Acyclovir Polymorphs.

Science.gov (United States)

Magnoni, Federico; Gigliobianco, Maria Rosa; Vargas Peregrina, Dolores; Censi, Roberta; Di Martino, Piera

2017-10-01

The present work investigated the solid state change of 4 acyclovir polymorphs when ground at room temperature (Method A) and under cryo-grinding in the presence of liquid nitrogen (Method B). Modifications in particle size and shape (evaluated by scanning electron microscopy) and in the water content (evaluated by thermal analysis) were related to transitions at the solid state, as confirmed by X-ray powder diffractometry. Anhydrous Form I was stable under grinding by both Methods A and B. The anhydrous Form II was stable during grinding under Method A, whereas it was progressively converted to the hydrate Form V during grinding under Method B. The hydrate Form V was stable under Method A, whereas it was converted to the anhydrous Form I after 15 min and then to the hydrate Form VI after 45 min of grinding. The hydrate Form VI proved to be stable under grinding by both Methods A and B. Thus, Form I and VI were the only forms that yielded a sizeable decrease in particle size under grinding, with a consequent increase in particle dissolution rate, while maintaining solid state physicochemical stability. Form I treated under Method B grinding gave the best dissolution rate. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Subsurface damage mechanism of high speed grinding process in single crystal silicon revealed by atomistic simulations

International Nuclear Information System (INIS)

Li, Jia; Fang, Qihong; Zhang, Liangchi; Liu, Youwen

2015-01-01

Highlights: • Molecular dynamic model of nanoscale high speed grinding of silicon workpiece has been established. • The effect of grinding speed on subsurface damage and grinding surface integrity by analyzing the chip, dislocation movement, and phase transformation during high speed grinding process are thoroughly investigated. • Subsurface damage is studied by the evolution of surface area at first time for more obvious observation on transition from ductile to brittle. • The hydrostatic stress and von Mises stress by the established analytical model are studied subsurface damage mechanism during nanoscale grinding. - Abstract: Three-dimensional molecular dynamics (MD) simulations are performed to investigate the nanoscale grinding process of single crystal silicon using diamond tool. The effect of grinding speed on subsurface damage and grinding surface integrity by analyzing the chip, dislocation movement, and phase transformation are studied. We also establish an analytical model to calculate several important stress fields including hydrostatic stress and von Mises stress for studying subsurface damage mechanism, and obtain the dislocation density on the grinding subsurface. The results show that a higher grinding velocity in machining brittle material silicon causes a larger chip and a higher temperature, and reduces subsurface damage. However, when grinding velocity is above 180 m s −1 , subsurface damage thickness slightly increases because a higher grinding speed leads to the increase in grinding force and temperature, which accelerate dislocation nucleation and motion. Subsurface damage is studied by the evolution of surface area at first time for more obvious observation on transition from ductile to brittle, that provides valuable reference for machining nanometer devices. The von Mises stress and the hydrostatic stress play an important role in the grinding process, and explain the subsurface damage though dislocation mechanism under high

Mapping Annual Forest Cover in Sub-Humid and Semi-Arid Regions through Analysis of Landsat and PALSAR Imagery

Directory of Open Access Journals (Sweden)

Yuanwei Qin

2016-11-01

Full Text Available Accurately mapping the spatial distribution of forests in sub-humid to semi-arid regions over time is important for forest management but a challenging task. Relatively large uncertainties still exist in the spatial distribution of forests and forest changes in the sub-humid and semi-arid regions. Numerous publications have used either optical or synthetic aperture radar (SAR remote sensing imagery, but the resultant forest cover maps often have large errors. In this study, we propose a pixel- and rule-based algorithm to identify and map annual forests from 2007 to 2010 in Oklahoma, USA, a transitional region with various climates and landscapes, using the integration of the L-band Advanced Land Observation Satellite (ALOS PALSAR Fine Beam Dual Polarization (FBD mosaic dataset and Landsat images. The overall accuracy and Kappa coefficient of the PALSAR/Landsat forest map were about 88.2% and 0.75 in 2010, with the user and producer accuracy about 93.4% and 75.7%, based on the 3270 random ground plots collected in 2012 and 2013. Compared with the forest products from Japan Aerospace Exploration Agency (JAXA, National Land Cover Database (NLCD, Oklahoma Ecological Systems Map (OKESM and Oklahoma Forest Resource Assessment (OKFRA, the PALSAR/Landsat forest map showed great improvement. The area of the PALSAR/Landsat forest was about 40,149 km2 in 2010, which was close to the area from OKFRA (40,468 km2, but much larger than those from JAXA (32,403 km2 and NLCD (37,628 km2. We analyzed annual forest cover dynamics, and the results show extensive forest cover loss (2761 km2, 6.9% of the total forest area in 2010 and gain (3630 km2, 9.0% in southeast and central Oklahoma, and the total area of forests increased by 684 km2 from 2007 to 2010. This study clearly demonstrates the potential of data fusion between PALSAR and Landsat images for mapping annual forest cover dynamics in sub-humid to semi-arid regions, and the resultant forest maps would be

Precision grinding of microarray lens molding die with 4-axes controlled microwheel

Directory of Open Access Journals (Sweden)

Yuji Yamamoto, Hirofumi Suzuki, Takashi Onishi1, Tadashi Okino and Toshimichi Moriwaki

2007-01-01

Full Text Available This paper deals with precision grinding of microarray lens (fly eye molding die by using a resinoid bonded diamond wheel. An ultra-precision grinding system of microarray lens molding die and new truing method of resinoid bonded diamond wheel were developed. In this system, a grinding wheel was four-dimensionally controlled with 1 nm resolution by linear scale feedback system and scanned on the workpiece surface. New truing method by using a vanadium alloy tool was developed and its performance was obtained with high preciseness and low wheel wear. Finally, the microarray lens molding dies of fine grain tungsten carbide (WC was tested with the resinoid bonded diamond wheel to evaluate grinding performance.

TECHNICAL NOTE: High-speed grinding using thin abrasive disks for microcomponents

Science.gov (United States)

Yeo, S. H.; Balon, S. A. P.

2002-01-01

This paper introduces the development of a high-speed grinding device for cylindrical grinding of microcomponents made of hard and brittle materials. The study made use of an ultraprecision diamond turning machine tool as a basic platform. The novelty of the device is based on the high-speed air bearing spindle with a thin grinding wheel, similar to the dicing technology for silicon wafer fabrication. The spindle attachment is inclined at an angle to the main spindle which holds the precision fixture mechanism via the vacuum chuck. Experiments have been conducted to verify the design and implementation of the grinding methodology. A feature size as small as 31 μm in diameter and average surface roughness of 98 nm were obtained in the experimental work. It is found that the work done is capable of manufacturing miniature components, such as microcylindrical stepped shafts.

Efficient Fuel Pretreatment: Simultaneous Torrefaction and Grinding of Biomass

DEFF Research Database (Denmark)

Saleh, Suriyati Binti; Hansen, Brian Brun; Jensen, Peter Arendt

2013-01-01

Combining torrefaction and grinding of biomass in one reactor may be an attractive fuel pretreatment process. A combined laboratory torrefaction and ball mill reactor has been constructed for studies of the influence of temperature and residence time on the product yields and particle size...... reductions of Danish wheat straw, spruce chips, and pine chips. On the basis of initial experiments, which evaluated the influence of reactor mass loading, gas flow, and grinding ball size and material, a standard experimental procedure was developed. The particle size reduction capability......, and ash composition, where straw has a higher alkali content. This and other studies indicate that the large difference in the alkali contents of the biomasses is the main cause for the observed difference in torrefaction characteristics. Experiments with separate particle heating and grinding showed...

Evaluation of ball and roller bearings restored by grinding

Science.gov (United States)

Parker, R. J.; Zaretsky, E. V.; Chen, S. M.

1976-01-01

A joint program was undertaken to restore by grinding those rolling-element bearings which are currently being discarded at aircraft engine and transmission overhaul. Three bearing types were selected from the UH-1 helicopter engine (T-53) and transmission for the pilot program. Groups of each of these bearings were visually and dimensionally inspected for suitability for restoration. A total of 250 bearings were restored by grinding. Of this number, 30 bearings from each type were endurance tested to a TBO of 1600 hours. No bearing failures occurred related to the restoration by grinding process. The two bearing failures which occurred were due to defective rolling elements and were typical of those which may occur in new bearings. The restorable component yield to the three groups was in excess of 90 percent.

"Grinding" cavities in polyurethane foam

Science.gov (United States)

Brower, J. R.; Davey, R. E.; Dixon, W. F.; Robb, P. H.; Zebus, P. P.

1980-01-01

Grinding tool installed on conventional milling machine cuts precise cavities in foam blocks. Method is well suited for prototype or midsize production runs and can be adapted to computer control for mass production. Method saves time and materials compared to bonding or hot wire techniques.

Controlled wear of vitrified abrasive materials for precision grinding ...

Indian Academy of Sciences (India)

The study of bonding hard materials such as aluminium oxide and cubic boron nitride (BN) and the nature of interfacial cohesion between these materials and glass is very important from the perspective of high precision grinding. Vitrified grinding wheels are typically used to remove large volumes of metal and to produce ...

Isoflavone profile in soymilk as affected by soybean variety, grinding, and heat-processing methods.

Science.gov (United States)

Zhang, Yan; Chang, Sam K C; Liu, Zhisheng

2015-05-01

Isoflavones impart health benefits and their overall content and profile in foods are greatly influenced at each step during processing. In this study, 2 soybean varieties (Prosoy and black soybean) were processed with 3 different grinding (ambient, cold, and hot grinding) and heating methods (traditional stove cooking, 1-phase UHT, and 2-phase UHT) for soymilk making. The results showed after cold, ambient, and hot grinding, the total isoflavones were 3917, 5013, and 5949 nmol/g for Prosoy; the total isoflavones were 4073, 3966, and 4284 nmol/g for black soybean. Grinding could significantly increase isoflavone extraction. The grinding process had a destructive effect on isoflavones and this effect varied with grinding temperature. Different heating methods had different effects on different isoflavone forms. Two soybean varieties showed distinct patterns with respect to the change of isoflavone profile during processing. © 2015 Institute of Food Technologists®

MHD Technology Transfer, Integration and Review Committee. Seventh semi-annual status report, April 1991--September 1991

Energy Technology Data Exchange (ETDEWEB)

1993-02-01

This seventh semi-annual status report of the MHD Technology Transfer, Integration and Review Committee (TTIRC) summarizes activities of the TTIRC during the period April 1991 through September 1991. It includes a summary and minutes of the General Committee meeting, progress summaries of ongoing POC contracts, discussions pertaining to technical integration issues in the POC program, and planned activities for the next six months. The meeting included test plan with Western coal, seed regeneration economics, power management for the integrated topping cycle and status of the Clean Coal Technology Proposal activities. Appendices cover CDIF operations HRSR development, CFFF operations etc.

Optimization of the dressing parameters in cylindrical grinding based on a generalized utility function

Science.gov (United States)

Aleksandrova, Irina

2016-01-01

The existing studies, concerning the dressing process, focus on the major influence of the dressing conditions on the grinding response variables. However, the choice of the dressing conditions is often made, based on the experience of the qualified staff or using data from reference books. The optimal dressing parameters, which are only valid for the particular methods and dressing and grinding conditions, are also used. The paper presents a methodology for optimization of the dressing parameters in cylindrical grinding. The generalized utility function has been chosen as an optimization parameter. It is a complex indicator determining the economic, dynamic and manufacturing characteristics of the grinding process. The developed methodology is implemented for the dressing of aluminium oxide grinding wheels by using experimental diamond roller dressers with different grit sizes made of medium- and high-strength synthetic diamonds type ??32 and ??80. To solve the optimization problem, a model of the generalized utility function is created which reflects the complex impact of dressing parameters. The model is built based on the results from the conducted complex study and modeling of the grinding wheel lifetime, cutting ability, production rate and cutting forces during grinding. They are closely related to the dressing conditions (dressing speed ratio, radial in-feed of the diamond roller dresser and dress-out time), the diamond roller dresser grit size/grinding wheel grit size ratio, the type of synthetic diamonds and the direction of dressing. Some dressing parameters are determined for which the generalized utility function has a maximum and which guarantee an optimum combination of the following: the lifetime and cutting ability of the abrasive wheels, the tangential cutting force magnitude and the production rate of the grinding process. The results obtained prove the possibility of control and optimization of grinding by selecting particular dressing

MODELING AND OPTIMIZATION OF CYLINDRICAL GRINDING PARAMETERS FOR MRR AND SURFACE ROUGHNESS

OpenAIRE

Kshitij R Patil1, Rupesh J Karande2, Dadaso D. Mohite3, Vishwas S Jadhav4

2017-01-01

Cylindrical grinding is one of the important metal cutting processes used extensively in the finishing operations. The grinding process plays an important role in every manufacturing activity. The surface properties can be altered by changing various grinding parameters in order to achieve best surface finish resulting in low surface roughness value and with possible maximum metal removal rate. Four parameters, namely spindle speed, feed rate, depth of cut and hardness of material were identi...

An efficient, robust, and inexpensive grinding device for herbal samples like Cinchona bark

DEFF Research Database (Denmark)

Hansen, Steen Honoré; Holmfred, Else Skovgaard; Cornett, Claus

2015-01-01

An effective, robust, and inexpensive grinding device for the grinding of herb samples like bark and roots was developed by rebuilding a commercially available coffee grinder. The grinder was constructed to be able to provide various particle sizes, to be easy to clean, and to have a minimum...... of dead volume. The recovery of the sample when grinding as little as 50 mg of crude Cinchona bark was about 60%. Grinding is performed in seconds with no rise in temperature, and the grinder is easily disassembled to be cleaned. The influence of the particle size of the obtained powders on the recovery...

Analysing a Relationship Between Wheel Wear and Cutting Forces During Diamond Grinding

Directory of Open Access Journals (Sweden)

M. A. Shavva

2014-01-01

Full Text Available In diamond grinding cutting forces affect the quality of the machined surface. We can estimate a wear rate of the diamond wheel by the magnitude of the forces and promptly resort to the restoration of its cutting properties. To solve this problem it is necessary to define a relationship between grinding wheel wear and cutting forces. There was no this dependence found in the sources of literature.The forces acting on a single worn diamond grain are considered to find the relationship between wheel wear and cutting forces. The main forces acting on the diamond grain are such as a reaction force of machining material, a frictional force over a worn place of the grain, and a total pressure on the contact surface of the grain and machining material. According to calculation results, in grinding the cutting forces are proportional to the hardness of machining material, and depend on the grain wear, as well as on the process operation conditions.The paper presents a technique for calculating the number of cutting (active grains per unit surface of diamond wheel to determine a total cutting force in grinding. The number of cutting grains depends on the properties of diamond wheel and on the operation conditions of grinding process.During grinding a total cutting force is calculated through the single grain cutting force, the number of cutting grains per unit surface of the grinding wheel and the contact area between the wheel and the work piece. Theoretical calculation of the forces is based on the condition that protrusions of all cutting grains are identical and all grains have a maximum wear, i.e. maximum worn place of grain.Calculations based on proposed theoretical formulas are compared with the calculations from the empirical formulas given in the literature. Varying the operation conditions of grinding makes the comparison. Convergence of results in the range of 5-20% is regarded as acceptable.On the BMSTU base flat diamond grinding of tungsten

Grinding Characteristics Of Directionally Aligned SiC Whisker Wheel-Comparison With Al2O3 Fiber Wheel

Institute of Scientific and Technical Information of China (English)

魏源迁; 山口胜美; 菊泽贤二; 洞口严; 中根正喜

2003-01-01

A unique SiC whisker wheel was invented,in which the whiskers were aligned normally to the grinding wheel surface.In this paper,grindabilities of the SiC whisker wheel are investigated and compared with those of other wheels of SiC grains,Al2O3 grains,as well as Al2O3 long and short fibres which were also aligned normally to the grinding wheel surface,respectively.The main research contents concern grinding characteristics of a directionally aligned SiC whisker wheel such as material-removal volume,wheel-wear rates,integrity of the ground surfaces,grinding ratios and grinding efficiency.Furthermore,grinding wheels of whiskers and fibres have a common disadvantage:they tend to load easily.The authors have proposed a simple method of loading-free grinding to overcome this propensity and investigate some related grinding characteristics under loading-free grinding conditions.

Flotation performances and surface properties of chalcopyrite with xanthate collector added before and after grinding

Science.gov (United States)

Peng, Huiqing; Wu, Di; Abdelmonem, Mohamed

In this study, effects of the collector added before grinding and after grinding on the subsequent flotation and mineral surface properties were investigated. The pH was controlled at 10 during the grinding and flotation processes opened to the atmosphere. With enough amounts of sodium butyl xanthate addition, adding the collector before grinding recovered more chalcopyrite than adding it after grinding in single mineral flotation. The Eh of each ground pulp before and after conditioning were measured and it was found that adding collector before grinding obtained higher and relatively suitable pulp potential for chalcopyrite flotation. Particle size analyses of the flotation products indicate that the different flotation recoveries occurred due to the different flotation losses in fine particles (flotation feedings and found that more carbon and oxygen, and less iron were remained on mineral surfaces when the collector was added before grinding, due to the higher collector adsorption capacity, larger free oxygen adsorbance and less iron oxide/hydroxide species.

Advances and patents about grinding equipments with nano-particle jet minimum quantity lubrication.

Science.gov (United States)

Jia, Dongzhou; Li, Changhe; Wang, Sheng; Zhang, Qiang; Hou, Yali

2014-01-01

In recent years, a large number of patents have been devoted to developing minimum quantity lubrication (MQL) grinding techniques that can significantly improve both environmentally conscious and energy saving and costeffective sustainable grinding fluid alternatives. Among them, one patent is about a controllable nano-fluids jet MQL grinding system based on electrostatic atomization. Using the principle of electrostatics, it can achieve the control of droplet transfer by charging the sprayed droplets. This system can improve the uniformity of the droplet spectrum, liquid deposition efficiency and effective utilization of liquid. It can also effectively control the movement patterns of the droplets, thereby reducing the pollution of the environment and providing better health protection for workers. Although researchers accomplished profound and systematic studies on MQL, especially on nano-particles jet MQL. It can solve the shortage of MQL in cooling performance, greatly improve the working environment, save energy and reduce costs to achieve a low-carbon manufacturing. The unique lubricating performance and tribological property of solid nano-particles form nano-particle shearing films at the grinding wheel/workpiece interface, which can enhance the lubricating performance of MQL grinding. Existing studies on MQL grinding equipments, however, cannot meet the needs of the technological development. Therefore, our research provided a general introduction of the latest patients and research progress of nanoparticles jet MQL grinding equipments presented by the research team from Qingdao Technological University.

Operating results of Kosmos Cement's O-SEPA separator for raw grinding

Energy Technology Data Exchange (ETDEWEB)

Ireland, T C [Consultec Ltd., Toronto (CA); Schultz, G K [Southdown Incorporated, Houston, TX (US)

1991-01-01

High efficiency separators were first introduced in the cement industry to improve the energy efficiency of finish grinding circuits. Lately, however, a great deal of interest has been focused on improving the energy efficiency of raw grinding circuits. High efficiency separators have successfully been installed in roller mills as well as in ball mill raw grinding circuits. This paper describes the operating experience of the first installation in North America using a high efficiency separator in a raw grinding circuit. This installation, commissioned in 1988 at the Louisville, Kentucky plant of Kosmos Cement, uses a conventional 4500 HP ball mill and a high efficiency dynamic separator to produce raw meal for a preheater kiln as well as high fineness limestone for sulphur scrubbing in a nearby power plant. The system uses kiln exhaust gases for drying both in the mill and in the separator. (author).

Grinding of WC–Co hardmetals

NARCIS (Netherlands)

Hegeman, J.B.J.W.; Hosson, J.Th.M. De; With, G. de

2001-01-01

This paper concentrates on the morphology of the ground surface of cobalt tungsten carbide (WC) composite materials that belong to the category of so-called hardmetals. A deformed and detached surface layer was found on top of the specimens after surface grinding with a diamond wheel. In order to

Effect of liquid active media on grinding and scratching of solids

International Nuclear Information System (INIS)

Pertsov, N.V.; Danilova, F.B.; Babat, I.G.

1975-01-01

In the present paper the influence of various liquid active media on grinding of tungsten carbide, hard alloy T 15 K 6, oxide of aluminium A995 and other materials with diamond grinding wheels is investigated. A grinding device is described. The results of the investigations show that materials with metallic type of bonds are most effectively treated in the medium of liquid metals; for material with an ionic structure the active media are water and aqueous solutions of electrolytes. It is pointed out that liquid active media will diminish the specific work of dispergation by as much as one order of magnitude

Ibuprofen-Amino Acids Co-Crystal Screening Via Co-Grinding Methods

Directory of Open Access Journals (Sweden)

Othman Muhamad Fitri

2016-01-01

Full Text Available The importance of pharmaceutical co-crystals now has been recognized in order to improve the research and development in pharmaceutical industries. Low solubility of active pharmaceutical ingredient (API has led to the growth of new pharmaceutical co-crystals formation as it enhances the physicochemical properties of the API. In this works, preparation of new co-crystal formation between ibuprofen (IBP with selected amino acid compounds were performed by using dry grinding and liquid assisted grinding (LAG techniques. Ibuprofen (IBP was selected as the API meanwhile glycine (GLY, L-alanine (ALA and L-proline (PRO were selected as co-crystal former (CCF agents. The products of IBP-co-former from grinding experiments for the formation of co-crystals were characterized and verified using X-Ray Powder Diffraction (XRPD, Differential Scanning Calorimetry (DSC and Fourier Transform Infra-Red Spectroscopy (FTIR. The finding reveals that the IBP-PRO co-crystals have successfully formed. For IBP-PRO system, new crystalline peaks from XRPD were recorded at 2θ values of 4.374°, 5.436° and 10.944° from dry grinding technique and 4.41°, 5.436° and 10.962° for liquid assisted grinding (LAG technique. A new melting point of 257.49 °C was discovered for IBP-ALA indicates the possibility of co-crystals formation. On the other hand, the analysis for IBP-GLY shows that no co-crystals formed in the system.

ANFIS Modeling of the Surface Roughness in Grinding Process

OpenAIRE

H. Baseri; G. Alinejad

2011-01-01

The objective of this study is to design an adaptive neuro-fuzzy inference system (ANFIS) for estimation of surface roughness in grinding process. The Used data have been generated from experimental observations when the wheel has been dressed using a rotary diamond disc dresser. The input parameters of model are dressing speed ratio, dressing depth and dresser cross-feed rate and output parameter is surface roughness. In the experimental procedure the grinding conditions...

Semi-annual report of the Department of Energy, Office of Environmental Management, Quality Assessment Program

Energy Technology Data Exchange (ETDEWEB)

Greenlaw, P.D.; Minick, S.K.

1998-07-01

This Quality Assessment Program (QAP) is designed to test the quality of the environmental measurements being reported to the Department of Energy by its contractors. Since 1976, real or synthetic environmental samples that have been prepared and thoroughly analyzed at the Environmental Measurements Laboratory (EML) have been distributed at first quarterly and then semi-annually to these contractors. Their results, which are returned to EML within 90 days, are compiled with EML`s results and are reported back to the participating contractors 30 days later. This report presents the results from the analysis of the 48th set of environmental quality assessment samples (QAP XLVIII) that were received on or before June 1, 1998.

Semi-annual report of the Department of Energy, Office of Environmental Management, Quality Assessment Program

International Nuclear Information System (INIS)

Greenlaw, P.D.; Minick, S.K.

1998-01-01

This Quality Assessment Program (QAP) is designed to test the quality of the environmental measurements being reported to the Department of Energy by its contractors. Since 1976, real or synthetic environmental samples that have been prepared and thoroughly analyzed at the Environmental Measurements Laboratory (EML) have been distributed at first quarterly and then semi-annually to these contractors. Their results, which are returned to EML within 90 days, are compiled with EML's results and are reported back to the participating contractors 30 days later. This report presents the results from the analysis of the 48th set of environmental quality assessment samples (QAP XLVIII) that were received on or before June 1, 1998

Nondestructive Evaluation of Ceramic Candle Filters Using Vibration Response

International Nuclear Information System (INIS)

Chen, Roger H.L.; Kiriakidis, Alejandro C.; Peng, Steve W.

1997-01-01

This study aims at the development of an effective nondestructive evaluation technique to predict the remaining useful life of a ceramic candle filter during a power plant's annual maintenance shutdown. The objective of the present on-going study is to establish the vibration signatures of ceramic candle filters at varying degradation levels due to different operating hours, and to study the various factors involving the establishment of the signatures

Comparison among the mineralogic characteristics of Corumbatai formation and a mass for via humidity ceramic coating

International Nuclear Information System (INIS)

Rocha, R.R.; Zanardo, A.; Moreno, M.M.T.

2009-01-01

The mineralogy of the raw materials used in the production of ceramic tiles is a matter of great importance considering the constant necessity of finding alternatives to reduce costs and to improve the product quality. The ceramic industry of Santa Gertrudes could see a dramatic growth due to reasons that include the natural characteristics of the raw materials found in the region which are suitable for the production of ceramic tiles through the dry grinding process. In order to understand the ease of use of such clays which are sedimentary rocks of Corumbatai Formation, their plastic components made up primarily of clay minerals such as illite and smectite, and non-plastic components, including quartz (inert), feldspars (fluxe) and some contaminants, were identified with the use of X-ray diffraction. When comparing the properties of the formulation made with clays from Corumbatai Formation with that made with raw materials for the wet process, it was possible to note the ease of use and the relative characteristics of both processes. (author)

The effect of grinding on magnetic properties of agglomereted MnFe2O4 nanoparticles

International Nuclear Information System (INIS)

Aslibeiki, B.; Kameli, P.; Salamati, H.

2012-01-01

The effects of grinding on interparticle magnetic interactions for an ensemble of agglomerated MnFe 2 O 4 nanoparticles have been studied. Structural analyses showed that by grinding the samples, a small variation in size of crystallites and lattice strain will occur. ac Magnetic susceptibility measurements under different conditions and spin dynamics analysis suggest that freezing temperature is frequency dependent and it is in good agreement with critical slowing down model. This is an indication that these nanoparticles have superspin glass behavior. The estimated zυ and τ 0 parameters using critical slowing down model show that by increasing the grinding time the interaction between nanoparticles decreases. ac Susceptibility measurements in cooling and heating process show a thermal hysteresis. The thermal hysteresis decreased by increasing the grinding time. Also, the thermal hysteresis is frequency dependent and it increased as frequency decreased. These results showed that interparticle interactions such as dipole-dipole and exchange interactions between nanoparticles become weaker by grinding. - Highlights: → We studied the effects of grinding on interparticle interactions of MnFe 2 O 4 nanoparticles. → Critical slowing model used to estimate the interparticle interaction strength. → The results showed interparticle interactions become weaker by grinding. → Ac Susceptibility shows the irreversibility of spins decreased by grinding.

Complete Chiral Resolution Using Additive-Induced Crystal Size Bifurcation During Grinding

NARCIS (Netherlands)

Noorduin, Wim L.; Asdonk, Pim van der; Meekes, Hugo; Enckevort, Willem J.P. van; Kaptein, Bernard; Leeman, Michel; Kellogg, Richard M.; Vlieg, Elias

2009-01-01

Grinding them down: By using a tailor-made additive, even in the absence of racemization in solution, abrasive grinding can yield an enantiopure solid state. This novel chiral resolution technique is based on an asymmetric bifurcation in the crystal size distribution as a result of stereoselective

Synthesis and characterization of grinding aid fly ash blended mortar effect on bond strength of masonry prisms

Science.gov (United States)

Krishnaraj, L.; Ravichandran, P. T.; Sagadevan, Suresh

2018-04-01

The aim of the present work is to study the effect of particle size reduction by applying top-down nanotechnology such as ball mill grinding process with the addition of amine-based grinding aids. The particle size reduction in synthesis process and its characterization were investigated for fly ash particles. The Rosin-Rammler-Bennet (RRB) distribution model using mathematical formulations were studied for fly ash ground particles. The hardened properties of grinding aid fly ash composite mortar were studied using compressive strength test. The optimum grinding time was 120 min identified through the particle size distribution analysis. The mean particle size decreased from 92.09 μm to 10.5 μm in which there is 89% reduction in particle size due to the grinding of fly ash particle with grinding aids. The compressive strength results show that substitutions of Ordinary Portland Cement (OPC) mortar by Amine-based Grinding aid Fly Ash (AGFA) 15% gives 12, 23% and at 30% gives 6, 8% of higher strength compare to the substitutions of raw fly ash. The addition of grinding aids in grinding process gives more advantages to reduce the particle size without changing chemical composition. The AGFA sample shows better performance in compressive strength and bond strength behavior of masonry prism. It may suggest that amine based grinding aids play a vital role and feasible to use in fly ash grinding process.

Effect of surface grinding on chloride induced SCC of 304L

Energy Technology Data Exchange (ETDEWEB)

Zhou, Nian, E-mail: nzh@du.se [Department of Material Science, Dalarna University, SE-79188 Falun (Sweden); KTH, SE-10044 Stockholm (Sweden); Pettersson, Rachel [KTH, SE-10044 Stockholm (Sweden); Jernkontoret, SE-11187 Stockholm (Sweden); Lin Peng, Ru [Department of Management and Engineering, Linköping University, SE-58183 Linköping (Sweden); Schönning, Mikael [Corrosion Department, Avesta Research Centre – Outokumpu Stainless AB, SE-774 22 Avesta (Sweden)

2016-03-21

The effect of surface grinding on the stress corrosion cracking (SCC) behavior of 304L austenitic stainless steel in boiling magnesium chloride has been investigated. SCC tests were conducted both without external loading and with varied levels of four-point bend loading for as-delivered material and for specimens which had been ground parallel or perpendicular to the loading direction. Residual stresses due to the grinding operation were measured using the X-ray diffraction technique. In addition, surface stress measurements under applied load were performed before exposure to evaluate the deviation between actual applied loading and calculated values according to ASTM G39. Micro-cracks initiated by a high level of tensile residual stress in the surface layer were observed for all the ground specimens but not those in the as-delivered condition. Grinding along the loading direction increased the susceptibility to chloride induced SCC; while grinding perpendicular to the loading direction improved SCC resistance. Surface tensile residual stresses were largely relieved after the initiation of cracks.

Effect of surface grinding on chloride induced SCC of 304L

International Nuclear Information System (INIS)

Zhou, Nian; Pettersson, Rachel; Lin Peng, Ru; Schönning, Mikael

2016-01-01

The effect of surface grinding on the stress corrosion cracking (SCC) behavior of 304L austenitic stainless steel in boiling magnesium chloride has been investigated. SCC tests were conducted both without external loading and with varied levels of four-point bend loading for as-delivered material and for specimens which had been ground parallel or perpendicular to the loading direction. Residual stresses due to the grinding operation were measured using the X-ray diffraction technique. In addition, surface stress measurements under applied load were performed before exposure to evaluate the deviation between actual applied loading and calculated values according to ASTM G39. Micro-cracks initiated by a high level of tensile residual stress in the surface layer were observed for all the ground specimens but not those in the as-delivered condition. Grinding along the loading direction increased the susceptibility to chloride induced SCC; while grinding perpendicular to the loading direction improved SCC resistance. Surface tensile residual stresses were largely relieved after the initiation of cracks.

FY 1998 annual report. Research and development on ceramic gas turbine (300kW class)

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-04-01

Research and development have been made on a small ceramic gas turbine which is high in efficiency, low in pollutant emission, capable of corresponding to different fuels, and can be utilized in cogeneration and/or movable electric power generation systems. Fundamental researches in developing and researching heat resistant ceramic parts have been carried out on a method for fabricating turbine nozzles using heat resistant silicon nitride, improvement in accuracy in fabricating combustors using the heat resistant silicon nitride, and casting of turbine blades made from sialon. In developing the devices, researches were made on reliability of bond between a ceramic blade and a metallic disk, air-fuel ratio in a combustor, distribution of fuel concentrations, fuel injection methods, reduction of loss in a diffuser in a compressor, and matching of the diffuser with an impeller. In addition, research and development were performed on a single shaft ceramic gas turbine for cogeneration and a double shaft ceramic gas turbine. Researches were executed on reliability of ceramic materials. (NEDO)

Analysis of process parameters in surface grinding using single objective Taguchi and multi-objective grey relational grade

Directory of Open Access Journals (Sweden)

Prashant J. Patil

2016-09-01

Full Text Available Close tolerance and good surface finish are achieved by means of grinding process. This study was carried out for multi-objective optimization of MQL grinding process parameters. Water based Al2O3 and CuO nanofluids of various concentrations are used as lubricant for MQL system. Grinding experiments were carried out on instrumented surface grinding machine. For experimentation purpose Taguchi's method was used. Important process parameters that affect the G ratio and surface finish in MQL grinding are depth of cut, type of lubricant, feed rate, grinding wheel speed, coolant flow rate, and nanoparticle size. Grinding performance was calculated by the measurement G ratio and surface finish. For improvement of grinding process a multi-objective process parameter optimization is performed by use of Taguchi based grey relational analysis. To identify most significant factor of process analysis of variance (ANOVA has been used.

Measurement of drill grinding parameters using laser sensor

Science.gov (United States)

Yanping, Peng; Kumehara, Hiroyuki; Wei, Zhang; Nomura, Takashi

2005-12-01

To measure the grinding parameters and geometry parameters accurately for a drill point is essential to its design and reconditioning. In recent years, a number of non-contact coordinate measuring apparatuses, using CCD camera or laser sensors, are developed. But, a lot work is to be done for further improvement. This paper reports another kind of laser coordinate meter. As an example of its application, the method for geometry inspection of the drill flank surface is detailed. Measured data from laser scanning on the flank surface around some points with several 2-dimensional curves are analyzed with mathematical procedure. If one of these curves turns to be a straight line, it must be the generatrix of the grinding cone. Thus, the grinding parameters are determined by a set of three generatrices. Then, the measurement method and data processing procedure are proposed. Its validity is assessed by measuring a sample with given parameters. The point geometry measured agrees well with the known values. In comparison with other methods in the published literature, it is simpler in computation and more accurate in results.

Techniques for chamfer and taper grinding of oxide fuel pellets (LWBR Development Program)

International Nuclear Information System (INIS)

Johnson, R.G.R.; Allison, J.W.

1981-10-01

Floor mounted centerless grinding machines were adapted for shaping the edges of cylindrical oxide fuel pellets for the Light Water Breeder Reactor (LWBR) by plunge grinding. Edge configurations consisted of chamfers, either 0.015 inch x 45 0 or 0.006 inch x 45 0 , or tapers 0.150 inch long x .0025 inch deep. Grinding was done by plunging the pellet against a shaped grinding wheel which ground both the diameter to the required size and shaped the edges of the pellet. Two plunges per pellet were required to complete the operation. Separate wheels were needed for grinding either a chamfer or a taper, the set up was adjustable to vary the size of the chamfer or taper as needed. The set up also had the flexibility to accommodate the multiple pellet lengths and diameters required by the LWBR design. Tight manufacturing tolerances in the chamfer and taper dimensions required the use of dimensional control charts and statistical sampling plans as process controls

An Efficient, Robust, and Inexpensive Grinding Device for Herbal Samples like Cinchona Bark.

Science.gov (United States)

Hansen, Steen Honoré; Holmfred, Else; Cornett, Claus; Maldonado, Carla; Rønsted, Nina

2015-01-01

An effective, robust, and inexpensive grinding device for the grinding of herb samples like bark and roots was developed by rebuilding a commercially available coffee grinder. The grinder was constructed to be able to provide various particle sizes, to be easy to clean, and to have a minimum of dead volume. The recovery of the sample when grinding as little as 50 mg of crude Cinchona bark was about 60%. Grinding is performed in seconds with no rise in temperature, and the grinder is easily disassembled to be cleaned. The influence of the particle size of the obtained powders on the recovery of analytes in extracts of Cinchona bark was investigated using HPLC.

Nanofluid as coolant for grinding process: An overview

Science.gov (United States)

Kananathan, J.; Samykano, M.; Sudhakar, K.; Subramaniam, S. R.; Selavamani, S. K.; Manoj Kumar, Nallapaneni; Keng, Ngui Wai; Kadirgama, K.; Hamzah, W. A. W.; Harun, W. S. W.

2018-04-01

This paper reviews the recent progress and applications of nanoparticles in lubricants as a coolant (cutting fluid) for grinding process. The role of grinding machining in manufacturing and the importance of lubrication fluids during material removal are discussed. In grinding process, coolants are used to improve the surface finish, wheel wear, flush the chips and to reduce the work-piece thermal deformation. The conventional cooling technique, i.e., flood cooling delivers a large amount of fluid and mist which hazardous to the environment and humans. Industries are actively looking for possible ways to reduce the volume of coolants used in metal removing operations due to the economical and ecological impacts. Thus as an alternative, an advanced cooling technique known as Minimum Quantity Lubrication (MQL) has been introduced to the enhance the surface finish, minimize the cost, to reduce the environmental impacts and to reduce the metal cutting fluid consumptions. Nanofluid is a new-fangled class of fluids engineered by dispersing nanometre-size solid particles into base fluids such as water, lubrication oils to further improve the properties of the lubricant or coolant. In addition to advanced cooling technique review, this paper also reviews the application of various nanoparticles and their performance in grinding operations. The performance of nanoparticles related to the cutting forces, surface finish, tool wear, and temperature at the cutting zone are briefly reviewed. The study reveals that the excellent properties of the nanofluid can be beneficial in cooling and lubricating application in the manufacturing process.

Matrix model of the grinding process of cement clinker in the ball mill

Science.gov (United States)

Sharapov, Rashid R.

2018-02-01

In the article attention is paid to improving the efficiency of production of fine powders, in particular Portland cement clinker. The questions of Portland cement clinker grinding in closed circuit ball mills. Noted that the main task of modeling the grinding process is predicting the granulometric composition of the finished product taking into account constructive and technological parameters used ball mill and separator. It is shown that the most complete and informative characterization of the grinding process in a ball mill is a grinding matrix taking into account the transformation of grain composition inside the mill drum. Shows how the relative mass fraction of the particles of crushed material, get to corresponding fraction. Noted, that the actual task of reconstruction of the matrix of grinding on the experimental data obtained in the real operating installations. On the basis of experimental data obtained on industrial installations, using matrix method to determine the kinetics of the grinding process in closed circuit ball mills. The calculation method of the conversion of the grain composition of the crushed material along the mill drum developed. Taking into account the proposed approach can be optimized processing methods to improve the manufacturing process of Portland cement clinker.

Research on precision grinding technology of large scale and ultra thin optics

Science.gov (United States)

Zhou, Lian; Wei, Qiancai; Li, Jie; Chen, Xianhua; Zhang, Qinghua

2018-03-01

The flatness and parallelism error of large scale and ultra thin optics have an important influence on the subsequent polishing efficiency and accuracy. In order to realize the high precision grinding of those ductile elements, the low deformation vacuum chuck was designed first, which was used for clamping the optics with high supporting rigidity in the full aperture. Then the optics was planar grinded under vacuum adsorption. After machining, the vacuum system was turned off. The form error of optics was on-machine measured using displacement sensor after elastic restitution. The flatness would be convergenced with high accuracy by compensation machining, whose trajectories were integrated with the measurement result. For purpose of getting high parallelism, the optics was turned over and compensation grinded using the form error of vacuum chuck. Finally, the grinding experiment of large scale and ultra thin fused silica optics with aperture of 430mm×430mm×10mm was performed. The best P-V flatness of optics was below 3 μm, and parallelism was below 3 ″. This machining technique has applied in batch grinding of large scale and ultra thin optics.

Metals and Ceramics Division. Annual progress report, ending June 30, 1980

Energy Technology Data Exchange (ETDEWEB)

1980-09-01

Research is reported concerning: (1) engineering materials, including materials compatibility, mechanical properties, nondestructive testing, pressure vessel technology, and welding and brazing; (2) fuels and processes consisting of ceramic technology, fuel cycle technology, fuels evaluation, fuel fabrication and metals processing; and (3) materials science which includes, ceramic studies, physical metallurgy properties, radiation effects and microstructural analysis, metastable and superconducting materials, structure and properties of surfaces, theroretical research and x-ray research and applications. Highlights of the work of the metallographic group and the current state of the High-Temperature Materials Laboratory (HTML) and the Materials and Structures Technology Management Center (MSTMC) are presented. (FS)

Metals and Ceramics Division. Annual progress report, ending June 30, 1980

International Nuclear Information System (INIS)

1980-09-01

Research is reported concerning: (1) engineering materials, including materials compatibility, mechanical properties, nondestructive testing, pressure vessel technology, and welding and brazing; (2) fuels and processes consisting of ceramic technology, fuel cycle technology, fuels evaluation, fuel fabrication and metals processing; and (3) materials science which includes, ceramic studies, physical metallurgy properties, radiation effects and microstructural analysis, metastable and superconducting materials, structure and properties of surfaces, theroretical research and x-ray research and applications. Highlights of the work of the metallographic group and the current state of the High-Temperature Materials Laboratory (HTML) and the Materials and Structures Technology Management Center (MSTMC) are presented

Semi-annual status report of the Canadian Nuclear Fuel Waste Management Program, April 1--September 30, 1991

Energy Technology Data Exchange (ETDEWEB)

Wright, E. D. [comp.

1992-02-01

This report is the eleventh in a series of semi-annual status reports on the research and development program for the safe management and disposal of Canada's nuclear fuel waste. it describes progress achieved in the three major subprograms, engineered systems, natural systems and performance assessment, from 1991 April 1 to September 30. It also gives a brief description of the activities being carried out in preparation for the public and governmental review of the disposal concept. Since 1987, this program has been jointly funded by AECL and Ontario Hydro under the auspices of the CANDU Owners Group (COG).

Research on Grinding and Polishing Force Control of Compliant Flange

Directory of Open Access Journals (Sweden)

Li Chuang

2015-01-01

Full Text Available The automation of the grinding and polishing process is important to improve the production efficiency of the part surfaces. In this paper, a new compliant flange mounted on the end of the industrial robots for the robotic grinding and polishing force control is developed. With regard to the non-linear and time-varying problem of the contact force, the mathematical model of the new force control system was presented and the fuzzy PID control strategy was used to drive the proposed system. Especially, the air spring and electric proportional valve is studied to establish the model. The simulation results show that the selected control strategy has quick response and good robustness, which satisfies the real-time requirements of the grinding and polishing force control in processing.

Manufacturing of Porous Ceramic Preforms Based on Halloysite Nanotubes (Hnts

Directory of Open Access Journals (Sweden)

Kujawa M.

2016-06-01

Full Text Available The aim of this study was to determine the influence of manufacturing conditions on the structure and properties of porous halloysite preforms, which during pressure infiltration were soaked with a liquid alloy to obtain a metal matrix composite reinforced by ceramic, and also to find innovative possibilities for the application of mineral nanotubes obtained from halloysite. The method of manufacturing porous ceramic preforms (based on halloysite nanotubes as semi-finished products that are applicable to modern infiltrated metal matrix composites was shown. The ceramic preforms were manufactured by sintering of halloysite nanotubes (HNT, Natural Nano Company (USA, with the addition of pores and canals forming agent in the form of carbon fibres (Sigrafil C10 M250 UNS SGL Group, the Carbon Company. The resulting porous ceramic skeletons, suggest innovative application capabilities mineral nanotubes obtained from halloysite.

Robustness of a cross contamination model describing transfer of pathogens during grinding of meat

DEFF Research Database (Denmark)

Møller, Cleide Oliveira de Almeida; Sant’Ana, A. S.; Hansen, Solvej Katrine Holm

2016-01-01

This study aimed to evaluate a cross contamination model for its capability of describing transfer of Salmonella spp. and L. monocytogenes during grinding of varying sizes and numbers of pieces of meats in two grinder systems. Data from 19 trials were collected. Three evaluation approaches were a...... that grinding was influenced by sharpness of grinder knife, specific grinder and grinding temperature....

Effects of hardness of abrasive grains on surface roughness of work piece in PVA bonded grinding wheel

International Nuclear Information System (INIS)

Nitta, S.; Takata, A.; Ishizaki, K.

2000-01-01

The purpose of this study is to clarify relation between hardness of abrasive grains and surface roughness of work piece in the case of PVA (Polyvinyl alcohol) bonded grinding wheels. Two PVA bonded grinding wheels; with diamond or silicon carbide as abrasive grains and grinding of glass and aluminum alloy was performed. The PVA bonded grinding wheels The PVA bonded grinding wheel with silicon carbide could not grind the glass. Because insufficiency in hardness, the PVA bonded grinding wheel with the diamond abrasive grains caused deep scratch on the aluminum alloy. It was found that the final surface roughness of the work piece was not proportional to the hardness of abrasive grains. The suitable hardness of abrasive grains will be obtained by the hardness of work piece. Copyright (2000) AD-TECH - International Foundation for the Advancement of Technology Ltd

Co-contraction behaviour of masticatory and neck muscles during tooth grinding.

Science.gov (United States)

Giannakopoulos, N N; Schindler, H J; Hellmann, D

2018-07-01

The objective of this study was to analyse the co-contraction behaviour of jaw and neck muscles during force-controlled experimental grinding in the supine position. Twelve symptom-free subjects were enrolled in the experimental study. Electromyographic (EMG) activity of semispinalis capitis, splenius capitis and levator scapulae muscles was recorded bilaterally with intramuscular fine-wire electrodes, whereas that of sternocleidomastoideus, infrahyoidal, suprahyoidal, masseter and anterior temporalis muscles were registered with surface electrodes. EMG and force measurements were performed during tasks simulating tooth grinding on custom-made intraoral metal splints. The mean EMG activity normalised by maximum voluntary contraction (% MVC) of each of the neck muscles studied during grinding was analysed and compared with previous data from jaw clenching at identical force (100 N) and (supine) position. The occurrence of low-level, long-lasting tonic activation (LLTA) of motor units was also documented. The mean three-dimensional force vector of the grinding forces was 106 ± 74 N. In the frontal plane, the incline to the midsagittal plane ranged between 10° and 15°. In the midsagittal plane, the incline to the frontal plane was negligibly small. Posterior neck muscle activity during grinding ranged between 4.5% and 12% MVC and during clenching with 100 N between 1.8% and 9.9% MVC. Masticatory muscle activity during grinding ranged between 17% and 21% MVC for contralateral masseter and ipsilateral temporalis and between 4% and 6.5% for ipsilateral masseter and contralateral temporalis. LLTA had an average duration of 195 ± 10 seconds. The findings from this study do not support pathophysiological muscle chain theories postulating simple biomechanical coupling of neck and jaw muscles. Co-contractions of neck and masticatory muscles may instead occur as a result of complex neurophysiological interactions. © 2018 John Wiley & Sons Ltd.

First Grinding of a Rock on Mars

Science.gov (United States)

2004-01-01

The round, shallow depression in this image resulted from history's first grinding of a rock on Mars. The rock abrasion tool on NASA's Spirit rover ground off the surface of a patch 45.5 millimeters (1.8 inches) in diameter on a rock called Adirondack during Spirit's 34th sol on Mars, Feb. 6, 2004. The hole is 2.65 millimeters (0.1 inch) deep, exposing fresh interior material of the rock for close inspection with the rover's microscopic imager and two spectrometers on the robotic arm. This image was taken by Spirit's panoramic camera, providing a quick visual check of the success of the grinding. The rock abrasion tools on both Mars Exploration Rovers were supplied by Honeybee Robotics, New York, N.Y.

Grinding efficiency of abutment tooth with both dentin and core composite resin on axial plane.

Science.gov (United States)

Miho, Otoaki; Sato, Toru; Matsukubo, Takashi

2015-01-01

The purpose of this study was to evaluate grinding efficiency in abutment teeth comprising both dentin and core composite resin in the axial plane. Grinding was performed over 5 runs at two loads (0.5 or 0.25 N) and two feed rates (1 or 2 mm/sec). The grinding surface was observed with a 3-D laser microscope. Tomographic images of the grinding surfaces captured perpendicular to the feed direction were also analyzed. Using a non-ground surface as a reference, areas comprising only dentin, both dentin and core composite resin, or only core composite resin were analyzed to determine the angle of the grinding surface. Composite resins were subjected to the Vickers hardness test and scanning electron microscopy. Data were statistically analyzed using a one-way analysis of variance and multiple comparison tests. Multiple regression analysis was performed for load, feed rate, and Vickers hardness of the build-up material depending on number of runs. When grinding was performed at a constant load and feed rate, a greater grinding angle was observed in areas comprising both dentin and composite resin or only composite resin than in areas consisting of dentin alone. A correlation was found between machinability and load or feed rate in areas comprising both dentin and composite resin or composite resin alone, with a particularly high correlation being observed between machinability and load. These results suggest that great caution should be exercised in a clinical setting when the boundary between the dentin and composite resin is to be ground, as the angle of the grinding surface changes when the rotating diamond point begins grinding the composite resin.

Determining the optimum process parameter for grinding operations using robust process

International Nuclear Information System (INIS)

Neseli, Suley Man; Asilturk, Ilhan; Celik, Levent

2012-01-01

We applied combined response surface methodology (RSM) and Taguchi methodology (TM) to determine optimum parameters for minimum surface roughness (Ra) and vibration (Vb) in external cylindrical grinding. First, an experiment was conducted in a CNC cylindrical grinding machine. The TM using L 27 orthogonal array was applied to the design of the experiment. The three input parameters were workpiece revolution, feed rate and depth of cut; the outputs were vibrations and surface roughness. Second, to minimize wheel vibration and surface roughness, two optimized models were developed using computer aided single objective optimization. The experimental and statistical results revealed that the most significant grinding parameter for surface roughness and vibration is workpiece revolution followed by the depth of cut. The predicted values and measured values were fairly close, which indicates 2 ( 94.99 R 2Ra =and 2 92.73) R 2Vb =that the developed models can be effectively used to predict surface roughness and vibration in the grinding. The established model for determination of optimal operating conditions shows that a hybrid approach can lead to success of a robust process

Simulation and experimental investigation of inner-jet electrochemical grinding of GH4169 alloy

Directory of Open Access Journals (Sweden)

Hansong LI

2018-03-01

Full Text Available GH4169 alloy is one of the most commonly used materials in aero engine turbine blades, but its machinability is poor because of its excellent strength at high temperatures. Electrochemical machining (ECM has become a common method for machining this alloy and other difficult-to-machine materials. Electrochemical grinding (ECG is a hybrid process combining ECM and conventional grinding. In this paper, investigations conducted on inner-jet ECG of GH4169 alloy are described. Two types of inner-jet ECG grinding wheels were used to machine a flat bottom surface. The machining process was simulated using COMSOL software, and machining gaps under different machining parameters were obtained. In addition, maximum feed rates and maximum material removal rates under different machining parameters were studied experimentally. The maximum sizes and the uniformity of the distributions of the gaps machined by the two grinding wheels were compared. The effects of different applied voltages on the machining results were also investigated. Keywords: Electrochemical grinding, GH4169 alloy, Inner-jet, Material removal rate, Maximum feed rate

Dry grinding of talc in a stirred ball mill

Directory of Open Access Journals (Sweden)

Cayirli Serkan

2016-01-01

Full Text Available The aim of this work was to investigate micro fine size dry grindability of talc in a stirred ball mill. The effects of various parameters such as grinding time, stirrer speed, powder filling ratio and ball filling ratio were investigated. Alumina balls were used as grinding media. Experiments were carried out using the 24 full factorial design. The main and interaction effects were evaluated using the Yates method. Test results were evaluated on the basis of product size and surface area.

Experimental and Numerical Investigations in Shallow Cut Grinding by Workpiece Integrated Infrared Thermopile Array.

Science.gov (United States)

Reimers, Marcel; Lang, Walter; Dumstorff, Gerrit

2017-09-30

The purpose of our study is to investigate the heat distribution and the occurring temperatures during grinding. Therefore, we did both experimental and numerical investigations. In the first part, we present the integration of an infrared thermopile array in a steel workpiece. Experiments are done by acquiring data from the thermopile array during grinding of a groove in a workpiece made of steel. In the second part, we present numerical investigations in the grinding process to further understand the thermal characteristic during grinding. Finally, we conclude our work. Increasing the feed speed leads to two things: higher heat flux densities in the workpiece and higher temperature gradients in the material.

Modeling and evaluating of surface roughness prediction in micro-grinding on soda-lime glass considering tool characterization

Science.gov (United States)

Cheng, Jun; Gong, Yadong; Wang, Jinsheng

2013-11-01

The current research of micro-grinding mainly focuses on the optimal processing technology for different materials. However, the material removal mechanism in micro-grinding is the base of achieving high quality processing surface. Therefore, a novel method for predicting surface roughness in micro-grinding of hard brittle materials considering micro-grinding tool grains protrusion topography is proposed in this paper. The differences of material removal mechanism between convention grinding process and micro-grinding process are analyzed. Topography characterization has been done on micro-grinding tools which are fabricated by electroplating. Models of grain density generation and grain interval are built, and new predicting model of micro-grinding surface roughness is developed. In order to verify the precision and application effect of the surface roughness prediction model proposed, a micro-grinding orthogonally experiment on soda-lime glass is designed and conducted. A series of micro-machining surfaces which are 78 nm to 0.98 μm roughness of brittle material is achieved. It is found that experimental roughness results and the predicting roughness data have an evident coincidence, and the component variable of describing the size effects in predicting model is calculated to be 1.5×107 by reverse method based on the experimental results. The proposed model builds a set of distribution to consider grains distribution densities in different protrusion heights. Finally, the characterization of micro-grinding tools which are used in the experiment has been done based on the distribution set. It is concluded that there is a significant coincidence between surface prediction data from the proposed model and measurements from experiment results. Therefore, the effectiveness of the model is demonstrated. This paper proposes a novel method for predicting surface roughness in micro-grinding of hard brittle materials considering micro-grinding tool grains protrusion

Off-flavor related volatiles in soymilk as affected by soybean variety, grinding, and heat-processing methods.

Science.gov (United States)

Zhang, Yan; Guo, Shuntang; Liu, Zhisheng; Chang, Sam K C

2012-08-01

Off-flavor of soymilk is a barrier to the acceptance of consumers. The objectionable soy odor can be reduced through inhibition of their formation or through removal after being formed. In this study, soymilk was prepared by three grinding methods (ambient, cold, and hot grinding) from two varieties (yellow Prosoy and a black soybean) before undergoing three heating processes: stove cooking, one-phase UHT (ultrahigh temperature), and two-phase UHT process using a Microthermics direct injection processor, which was equipped with a vacuuming step to remove injected water and volatiles. Eight typical soy odor compounds, generated from lipid oxidation, were extracted by a solid-phase microextraction method and analyzed by gas chromatography. The results showed that hot grinding and cold grinding significantly reduced off-flavor as compared with ambient grinding, and hot grinding achieved the best result. The UHT methods, especially the two-phase UHT method, were effective to reduce soy odor. Different odor compounds showed distinct concentration patterns because of different formation mechanisms. The two varieties behaved differently in odor formation during the soymilk-making process. Most odor compounds could be reduced to below the detection limit through a combination of hot grinding and two-phase UHT processing. However, hot grinding gave lower solid and protein recoveries in soymilk.

Effects of Sawdust and Rice husk Additives on Physical Properties of Ceramic Filter

Directory of Open Access Journals (Sweden)

Majid. Muhi Shukur

2017-11-01

Full Text Available Two processes were employed for forming, specifically,  slip casting and semi-dry press were used to manufacture ceramic filters from local raw materials, red clay and combustible materials  (sawdust and rice husk. Different proportions of additives were used as pores forming agents to create porosity in ceramic filter. Dried filters  were fired at temperature to 1000°C.   It was found that the forming technique and additives have great effect on the physical properties of the produced ceramic filters. The slip casting technique was more suitable procedure for producing a porous ceramic filter. As well as, porosity increased as percentage of the combustible materials increased.

Developing a trend prediction model of subsurface damage for fixed-abrasive grinding of optics by cup wheels.

Science.gov (United States)

Dong, Zhichao; Cheng, Haobo

2016-11-10

Fixed-abrasive grinding by cup wheels plays an important role in the production of precision optics. During cup wheel grinding, we strive for a large removal rate while maintaining fine integrity on the surface and subsurface layers (academically recognized as surface roughness and subsurface damage, respectively). This study develops a theoretical model used to predict the trend of subsurface damage of optics (with respect to various grinding parameters) in fixed-abrasive grinding by cup wheels. It is derived from the maximum undeformed chip thickness model, and it successfully correlates the pivotal parameters of cup wheel grinding with the subsurface damage depth. The efficiency of this model is then demonstrated by a set of experiments performed on a cup wheel grinding machine. In these experiments, the characteristics of subsurface damage are inspected by a wedge-polishing plus microscopic inspection method, revealing that the subsurface damage induced in cup wheel grinding is composed of craterlike morphologies and slender cracks, with depth ranging from ∼6.2 to ∼13.2  μm under the specified grinding parameters. With the help of the proposed model, an optimized grinding strategy is suggested for realizing fine subsurface integrity as well as high removal rate, which can alleviate the workload of subsequent lapping and polishing.

ANALYSIS OF THE SURFACE PROFILE AND ITS MATERIAL SHARE DURING THE GRINDING INCONEL 718 ALLOY

Directory of Open Access Journals (Sweden)

Martin Novák

2015-05-01

Full Text Available Grinding is still an important method for surface finishing. At FPTM JEPU research, which deals with this issue is conducted. Experiments are carried out with grinding various materials under different conditions and then selected components of the surface integrity are evaluated. They include roughness Ra, Rm and Rz, Material ratio curve (Abbott Firestone curve and also the obtained roundness. This article deals with grinding nickel Inconel 718 alloy, when selected cutting grinding conditions were used and subsequently the surface profile and the material ratio curve were measured and evaluated.

The effect of seed moisture and temperature on grinding characteristics of quinoa (Chenopodium quinoa Willd.

Directory of Open Access Journals (Sweden)

Hassoon Waleed Hameed

2018-01-01

Full Text Available Quinoa (Chenopodium quinoa Willd is a native food plant of the Andean region of South America. Quinoa seeds have remarkable nutritional properties, not only from its high protein content, but also from its good amino acid balance. The aim of the study was evaluate the influence of quinoa seed moisture content (10, 12, 14, 16 and 18% and temperature (-20, 3, 20 and 40°C, with the initial grain moisture content of 10.5% on grinding process. Especially the particle size distributions and grinding energy indices were determined. The results showed that the increase of seed moisture content from 10 to 16% caused an increase the specific grinding energy from 6.9 to 8.3 kJ·kg-1, beside of this as the moisture increased the average particle also increased. The highest changes were observed in the fraction of coarse particles (above 1.0 mm. Interestingly, the mass fraction of fine particles (below 0.2 mm also increased. Other grinding indices also confirmed an increase the grinding energy requirements with the increase seed moisture content. The temperature of seed has little influence on quinoa grinding process. The highest grinding energy requirements were observed when the frozen seeds were ground.

Poly(ethylene glycol)s as grinding additives in the mechanochemical preparation of highly functionalized 3,5-disubstituted hydantoins.

Science.gov (United States)

Mascitti, Andrea; Lupacchini, Massimiliano; Guerra, Ruben; Taydakov, Ilya; Tonucci, Lucia; d'Alessandro, Nicola; Lamaty, Frederic; Martinez, Jean; Colacino, Evelina

2017-01-01

The mechanochemical preparation of highly functionalized 3,5-disubstituted hydantoins was investigated in the presence of various poly(ethylene) glycols (PEGs), as safe grinding assisting agents (liquid-assisted grinding, LAG). A comparative study under dry-grinding conditions was also performed. The results showed that the cyclization reaction was influenced by the amount of the PEG grinding agents. In general, cleaner reaction profiles were observed in the presence of PEGs, compared to dry-grinding procedures.

Wear properties of dental ceramics and porcelains compared with human enamel.

Science.gov (United States)

D'Arcangelo, Camillo; Vanini, Lorenzo; Rondoni, Giuseppe D; De Angelis, Francesco

2016-03-01

Contemporary pressable and computer-aided design/manufacturing (CAD/CAM) ceramics exhibit good mechanical and esthetic properties. Their wear resistance compared with human enamel and traditional gold based alloys needs to be better investigated. The purpose of this in vitro study was to compare the 2-body wear resistance of human enamel, gold alloy, and 5 different dental ceramics, including a recently introduced zirconia-reinforced lithium silicate ceramic (Celtra Duo). Cylindrical specimens were fabricated from a Type III gold alloy (Aurocast8), 2 hot pressed ceramics (Imagine PressX, IPS e.max Press), 2 CAD/CAM ceramics (IPS e.max CAD, Celtra Duo), and a CAD/CAM feldspathic porcelain (Vitablocs Mark II) (n=10). Celtra Duo was tested both soon after grinding and after a subsequent glaze firing cycle. Ten flat human enamel specimens were used as the control group. All specimens were subjected to a 2-body wear test in a dual axis mastication simulator for 120000 loading cycles against yttria stabilized tetragonal zirconia polycrystal cusps. The wear resistance was analyzed by measuring the vertical substance loss (mm) and the volume loss (mm(3)). Antagonist wear (mm) was also recorded. Data were statistically analyzed with 1-way ANOVA tests (α=.05). The wear depth (0.223 mm) of gold alloy was the closest to that of human enamel (0.217 mm), with no significant difference (P>.05). The greatest wear was recorded on the milled Celtra Duo (wear depth=0.320 mm), which appeared significantly less wear resistant than gold alloy or human enamel (Pceramics did not statistically differ in comparison with the human enamel. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Multiobjective Optimization of ELID Grinding Process Using Grey Relational Analysis Coupled with Principal Component Analysis

Directory of Open Access Journals (Sweden)

S. Prabhu

2014-06-01

Full Text Available Carbon nanotube (CNT mixed grinding wheel has been used in the electrolytic in-process dressing (ELID grinding process to analyze the surface characteristics of AISI D2 Tool steel material. CNT grinding wheel is having an excellent thermal conductivity and good mechanical property which is used to improve the surface finish of the work piece. The multiobjective optimization of grey relational analysis coupled with principal component analysis has been used to optimize the process parameters of ELID grinding process. Based on the Taguchi design of experiments, an L9 orthogonal array table was chosen for the experiments. The confirmation experiment verifies the proposed that grey-based Taguchi method has the ability to find out the optimal process parameters with multiple quality characteristics of surface roughness and metal removal rate. Analysis of variance (ANOVA has been used to verify and validate the model. Empirical model for the prediction of output parameters has been developed using regression analysis and the results were compared for with and without using CNT grinding wheel in ELID grinding process.

Experimental and Numerical Investigations in Shallow Cut Grinding by Workpiece Integrated Infrared Thermopile Array

Directory of Open Access Journals (Sweden)

Marcel Reimers

2017-09-01

Full Text Available The purpose of our study is to investigate the heat distribution and the occurring temperatures during grinding. Therefore, we did both experimental and numerical investigations. In the first part, we present the integration of an infrared thermopile array in a steel workpiece. Experiments are done by acquiring data from the thermopile array during grinding of a groove in a workpiece made of steel. In the second part, we present numerical investigations in the grinding process to further understand the thermal characteristic during grinding. Finally, we conclude our work. Increasing the feed speed leads to two things: higher heat flux densities in the workpiece and higher temperature gradients in the material.

Retificação da alumina com rebolo diamantado utilizando-se diferentes métodos de lubri-refrigeração Grinding of alumina with diamod wheel using different cooling methods

Directory of Open Access Journals (Sweden)

M. C. S Alves

2010-06-01

lack of reliability of ceramic components, because the variability on the mechanical strength caused by defects that can be impaired in the grinding process. The grinding of ceramics, as much as with steel grinding is performed generally with excess of cutting fluids (coolants. The use of coolants results in serious ecological, physiological and economic issues. Since last decade the public opinion, the market, the laws and regulations have pushed the industries to consider the environmental risks in the manufacturing process. Then, in order to evaluate alternatives to the conventional method of cooling and lubrication, it was studied the viability of the optimized technique, where the cutting fluid is applied to the same peripherical speed of the wheel, penetrating in the cutting zone with less turbulence. Also, it was verified the technique of Minimum Quantity of Lubricant (MQL, where a large amount of cutting fluid is replaced by an air compressed flow containing a small quantity of lubricant. The methods were compared through performance analysis of cutting forces, roughness and wheel (G ratio. As a conclusion is that MQL is not viable in ceramics grinding with the working conditions proposed. The results obtained with optimized technique are insufficient to state this technique presents better roughness and G-ratio values when compared to conventional method.

Temperature measurement of flat glass edge during grinding and effect of wheel and workpiece speeds

International Nuclear Information System (INIS)

Moussa, Tala; Garnier, Bertrand; Peerhossaini, Hassan

2017-01-01

Flat glass temperature at the vicinity of the grinding wheel during grinding can become very high and reach that of the glass transition (typically around 550–600 °C). In such cases, the mechanical strength of glass is greatly affected and the grinding process cannot be carried out properly. Hence, thermal phenomena must be managed by adjusting the machining parameters to avoid overheating. For this purpose, it is very important to be able to measure the glass temperature, especially at the grinding interface. However, measuring the interfacial glass temperature is difficult and none of the existing methods for metal grinding is adequate for glass grinding. This work shows a novel temperature method that uses constantan and copper strips on both sides of the glass plates; thermoelectric contact being provided by the metallic binder of diamond particles in the grinding wheel. This new technique allows the measurement of the glass edge temperature during the wheel displacement around the glass plate. The experimental results show an average glass edge temperature between 300 and 600 °C depending on the value of the machining parameters such as work speed, wheel speed, depth of cut and water coolant flow rate. As this new thermal instrumentation is rather intrusive, glass temperature biases were analysed using a 3D heat transfer model with a moving source. Model computations performed using finite elements show that the temperature biases are less than 70 °C, which is smaller than the standard deviation of the glass edge temperatures measured during grinding. (paper)

Reducing the Edge Chipping for Capillary End Face Grinding and Polishing

Directory of Open Access Journals (Sweden)

Hošek J.

2013-05-01

Full Text Available This paper presents results of glass capillary end face grinding and polishing by approach that reduces the edge chipping. Brittle materials have natural tendency for edge chipping what leads to beveling the sharp edges. Not beveled sharp edges on glass capillary are important for special applications like surface tension measurement of small liquid samples. We use common grinding and polishing process for capillary end face machining modified with gradual decreasing of grinding load based on the relation of the critical chipping load. Achieved surface roughness is measured using atomic force microscopy (AFM. Capillary inner edge quality is checked both with optical microscopes and electron microscope too. We achieved a non-chipped capillary inner edge with radius down to 100 nm.

Improved coal grinding and fuel flow control in thermal power plants

DEFF Research Database (Denmark)

Niemczyk, Piotr; Bendtsen, Jan Dimon

2011-01-01

A novel controller for coal circulation and pulverized coal flow in a coal mill is proposed. The design is based on optimal control theory for bilinear systems with additional integral action. The states are estimated from the grinding power consumption and the amount of coal accumulated in the m......A novel controller for coal circulation and pulverized coal flow in a coal mill is proposed. The design is based on optimal control theory for bilinear systems with additional integral action. The states are estimated from the grinding power consumption and the amount of coal accumulated...... as well as when parameter uncertainties and noise are present. The proposed controller lowers the grinding power consumption while in most cases exhibiting superior performance in comparison with the PID controller....

Investigations on the effect of forage source, grinding, and urea supplementation on ruminal fermentation and microbial protein flow in a semi-continuous rumen simulation system.

Science.gov (United States)

Hildebrand, Bastian; Boguhn, Jeannette; Rodehutscord, Markus

2011-10-01

The objective of the present study was to compare the effect of maize silage and grass silage on microbial fermentation and protein flow in a semi-continuous rumen simulation system (Rusitec) when milling screen size (MSS) during grinding was varied. Oven-dried silages were milled through screens of 1, 4 or 9 mm pore size and incubated for 48 h in a Rusitec system. Furthermore, the effect of N supplementation to maize silage (MSS: 4 mm) was investigated and single dose vs. continuous infusion of urea-N were compared. Degradation of organic matter (OM), crude protein (CP), fibre fractions and non-structural carbohydrates (NSC) as well as short-chain fatty acid production differed significantly between forage sources. Urea-N supplementation improved the degradation of NSC, but not that of fibre fractions in maize silage. The way of urea supply had only marginal effects on fermentation characteristics. An increase in MSS, and consequently in mean feed particle size, led to an improvement in the degradation of OM, CP and NSC, but efficiency of microbial net protein synthesis (EMPS; mg microbial N flow/g degraded OM) and the microbial amino acid profile were less affected. EMPS was higher in grass silage than in maize silage and was improved by urea-N supplementation in maize silage. This study indicates that fermentation of NSC as well as EMPS during incubation of maize silage was limited by availability of NH3-N. Furthermore, an increase in MSS above 1 mm seems to improve fermentation of silages in the Rusitec system.

Fragmentation process of vitrified ceramic waste (VCW) aiming its incorporation in silico-aluminous refractory concrete for production of refractory bricks; Processo de fragmentacao de residuos ceramicos vitrificados (RCV) visando sua incorporacao em concreto refratario silico-aluminoso

Energy Technology Data Exchange (ETDEWEB)

Gomes, L.B.; Brandalise, R.N.; Santos, V. dos, E-mail: lbgomes@ucs.br [Universidade de Caxias do Sul (UCS), RS (Brazil); Bergmann, C.P. [Universidade Federal do Rio Grande do Sul (UFRGS), RS (Brazil)

2012-07-01

Ceramic industry generates large amounts of waste, usually disposed in landfills. Reuse could minimize their generation and provides sustainable solutions. However, the energy cost of grinding these waste becomes a hindrance to their reuse. This work aims to obtain particle sizes of vitrified ceramic waste (VCW) using a fast, efficient and low cost fragmentation process as well as its use in refractory concrete. The results shows a wide range of particle size of VCW, which can be used as a promising source of raw material for production of refractory concrete. (author)

Fine grinding of brittle minerals and materials by jet mill

Directory of Open Access Journals (Sweden)

Lek Sikong

2008-05-01

Full Text Available Various variables affecting grinding, such as air pressure, minerals or materials hardness, feed size were investigated.The limitations of grinding of gypsum, barite, ilmenite, quartz and ferrosilicon were also elucidated by means of particlefineness size distribution and morphology of ground products. It was found that:1 The density of particles, which are in the grinding zone affects the product fineness, i.e. higher feed rate resultsin a larger product size. The appropriate feed rate is suggested to be 0.2~0.5 g/s. Moreover, the density and hardness ofminerals or materials tend to have an effect on the product fineness. Heavy minerals, such as barite or ilmenite, exhibit afiner product size than lighter minerals, like quartz. However, for quartz, the higher hardness also results in a larger d50.2 Air pressure is the most vital variable which affects the grinding by a jet mill. The d50 seems to relate to theapplied air pressure as a power law equation expressed as following:d50 = aP b ; as P 0The a-value and b-value have been found to correlate to the feed size. The higher the air pressure applied the finerthe product size attained. Moreover, air pressure has a greater effect on hard minerals than on softer ones.3 Feed size seems to have a small effect on ground the product fineness of soft materials, such as gypsum andbarite, but a significant effect on that of hard materials, such as ferrosilicon and quartz, in particularly by milling at low airpressures of 2~3 kg/cm2.4 For the breakage behavior and morphology of ground materials, it was also found that the minerals having cleavages,such as gypsum and barite, tend to be broken along their cleavage planes. Thus, the particle size distribution of theseproducts becomes narrower. While quartz, ilmenite, and ferrosilicon have shattering and chipping breakage mechanisms,grinding results in angular shapes of the ground products and a wider size distribution. Blocks or platelets and

The Effect of the Wear of Rotor Pins on Grinding Efficiency in a High-speed Disintegrator

OpenAIRE

Karel DVOŘÁK; Dušan DOLÁK; David PALOUŠEK; Ladislav ČELKO; David JECH

2018-01-01

One of the directions intensively investigated in the field of milling is high-energy milling (HEM). One type of HEM is high-speed grinding in high-speed disintegrators. This type of mill is particularly suitable for the grinding and activation of fine powder materials. It has several advantages, such as a very intensive and continual refining process. One disadvantage is that its grinding pins are prone to abrasion, which may result in a decrease of the efficiency of grinding. This effect wa...

Rubber lining design for grinding mills: influence on economy and capacity

Energy Technology Data Exchange (ETDEWEB)

Nillson, G

1979-11-01

There is a difference in design parameters between steel linings and rubber linings for grinding mills. The basic design parameters for rubber are described and a comparison is made between steel and rubber in different applications. If a rubber lining is correctly designed, it will give at least the same capacity as any other type of lining. A rubber lining can often be made thinner than other types of lining and, in such cases, the increased mill diameter will increase the capacity. What has been said above regarding capacity applies equally to grinding efficiency. The grind can sometimes be changed by altering the lifter height and lifter profile. Rubber linings of the correct quality and design will always give improved lining economy, except for large primary ball mills. We trust that new designs and rubber qualities will change the picture in the future. What is said about lining economy is especially true when taking reduced downtime and maintenance into consideration. The lining must be designed to reduce sliding over the shell, which leads to heavy wear. When used for dry grinding, the adverse effects of temperature must be observed.

Determining the optimum process parameter for grinding operations using robust process

Energy Technology Data Exchange (ETDEWEB)

Neseli, Suley Man; Asilturk, Ilhan; Celik, Levent [Univ. of Selcuk, Konya (Turkmenistan)

2012-11-15

We applied combined response surface methodology (RSM) and Taguchi methodology (TM) to determine optimum parameters for minimum surface roughness (Ra) and vibration (Vb) in external cylindrical grinding. First, an experiment was conducted in a CNC cylindrical grinding machine. The TM using L{sup 27} orthogonal array was applied to the design of the experiment. The three input parameters were workpiece revolution, feed rate and depth of cut; the outputs were vibrations and surface roughness. Second, to minimize wheel vibration and surface roughness, two optimized models were developed using computer aided single objective optimization. The experimental and statistical results revealed that the most significant grinding parameter for surface roughness and vibration is workpiece revolution followed by the depth of cut. The predicted values and measured values were fairly close, which indicates 2 ( 94.99 R{sup 2Ra}=and 2 92.73) R{sup 2Vb}=that the developed models can be effectively used to predict surface roughness and vibration in the grinding. The established model for determination of optimal operating conditions shows that a hybrid approach can lead to success of a robust process.

Determination of rational parameters for process of grinding materials pre-crushed by pressure in ball mill

Science.gov (United States)

Romanovich, A. A.; Romanovich, L. G.; Chekhovskoy, E. I.

2018-03-01

The article presents the results of experimental studies on the grinding process of a clinker preliminarily ground in press roller mills in a ball mill equipped with energy exchange devices. The authors studied the influence of the coefficients of loading for grinding bodies of the first and second mill chambers, their lengths, angles of inclination, and the mutual location of energy exchange devices (the ellipse segment and the double-acting blade) on the output parameters of the grinding process (productivity, drive power consumption and specific energy consumption). It is clarified that the best results of the disaggregation and grinding process, judging by the minimum specific energy consumption in the grinding of clinker with an anisotropic texture after force deformation between the rolls of a press roller shredder, are achieved at a certain angle of ellipse segment inclination; the length of the first chamber and the coefficients of loading the chambers with grinding bodies.

Rotary ultrasonic machining of CFRP: A comparison with grinding.

Science.gov (United States)

Ning, F D; Cong, W L; Pei, Z J; Treadwell, C

2016-03-01

Carbon fiber reinforced plastic (CFRP) composites have been intensively used in various industries due to their superior properties. In aircraft and aerospace industry, a large number of holes are required to be drilled into CFRP components at final stage for aircraft assembling. There are two major types of methods for hole making of CFRP composites in industry, twist drilling and its derived multi-points machining methods, and grinding and its related methods. The first type of methods are commonly used in hole making of CFRP composites. However, in recent years, rotary ultrasonic machining (RUM), a hybrid machining process combining ultrasonic machining and grinding, has also been successfully used in drilling of CFRP composites. It has been shown that RUM is superior to twist drilling in many aspects. However, there are no reported investigations on comparisons between RUM and grinding in drilling of CFRP. In this paper, these two drilling methods are compared in five aspects, including cutting force, torque, surface roughness, hole diameter, and material removal rate. Copyright © 2015 Elsevier B.V. All rights reserved.

Modelling transfer of Salmonella Typhimurium DT104 during simulation of grinding of pork

DEFF Research Database (Denmark)

Møller, Cleide; Nauta, Maarten; Christensen, B. B.

2012-01-01

Aims: The aim of this study was to develop a model to predict cross‐contamination of Salmonella during grinding of pork. Methods and Results: Transfer rates of Salmonella were measured in three experiments, where between 10 and 20 kg meat was ground into 200‐g portions. In each experiment, five...... during a small‐scale grinding process. It was, therefore, hypothesized that transfer occurred from two environmental matrices inside the grinder and a model was developed. The developed model satisfactorily predicted the observed concentrations of Salmonella during its cross‐contamination in the grinding...

Biopharmaceutical characterization of praziquantel cocrystals and cyclodextrin complexes prepared by grinding.

Science.gov (United States)

Cugovčan, Martina; Jablan, Jasna; Lovrić, Jasmina; Cinčić, Dominik; Galić, Nives; Jug, Mario

2017-04-15

Mechanochemical activation using several different co-grinding additives was applied as a green chemistry approach to improve physiochemical and biopharmaceutical properties of praziquantel (PZQ). Liquid assisted grinding with an equimolar amount of citric acid (CA), malic acid (MA), salicylic acid (SA) and tartaric acid (TA) gained in cocrystal formation, which all showed pH-dependent solubility and dissolution rate. However, the most soluble cocrystal of PZQ with MA was chemically unstable, as seen during the stability testing. Equimolar cyclodextrin complexes prepared by neat grinding with amorphous hydroxypropyl-β-cyclodextrin (HPβCD) and randomly methylated β-cyclodextrin (MEβCD) showed the highest improvement in drug solubility and the dissolution rate, but only PZQ/HPβCD product presented an acceptable chemical and photostability profile. A combined approach, by co-grinding the drug with both MA and HPβCD in equimolar ratio, also gave highly soluble amorphous product which again was chemical instable and therefore not suitable for the pharmaceutical use. Studies on Caco-2 monolayer confirmed the biocompatibility of PZQ/HPβCD complex and showed that complexation did not adversely affect the intrinsically high PZQ permeability (P app (PZQ)=(3.72±0.33)×10 -5 cms -1 and P app (PZQ/HPβCD)=(3.65±0.21)×10 -5 cms -1 ; p>0.05). All this confirmed that the co-grinding with the proper additive is as a promising strategy to improve biopharmaceutical properties of the drug. Copyright © 2017 Elsevier B.V. All rights reserved.

Basic research in crystalline and noncrystalline ceramic systems. Annual report, August 1, 1980-October 31, 1981

International Nuclear Information System (INIS)

1981-01-01

The Basic Research Programs in Ceramics sponsored by the US Department of Energy supports a significant fraction of the research effort and graduate student training in ceramics at MIT. Various research activities involving ceramic materials include electrical properties; kinetic studies; defect structures, defect interactions, grain boundaries and surfaces; sintering studies; and mechanical properties

Effect of disintegration wave grinding on fractional protein and amino acid composition of chickpea

OpenAIRE

G. O. Magomedov; M. K. Sadigova; S. I. Lukina; V. Y. Kustov

2013-01-01

The study of fractional changes and amino acid composition of proteins in the application of chickpea disintegration wave grinding. Comparative analysis of six varieties of chickpea before and after grinding.

Dependence of rates of breakage on fines content in wet ball mill grinding

Science.gov (United States)

Bhattacharyya, Anirban

The following research fundamentally deals with the cause and implications of nonlinearities in breakage rates of materials in wet grinding systems. The innate dependence of such nonlinearities on fines content and the milling environment during wet grinding operations is also tested and observed. Preferential breakage of coarser size fractions as compared to the finer size fractions in a particle population were observed and discussed. The classification action of the pulp was deemed to be the probable cause for such a peculiarity. Ores with varying degrees of hardness and brittleness were used for wet grinding experiments, primarily to test the variations in specific breakage rates as a function of varying hardness. For this research, limestone, quartzite, and gold ore were used. The degree of hardness is of the order of: limestone, quartzite, gold ore. Selection and breakage function parameters were determined in the course of this research. Functional forms of these expressions were used to compare experimentally derived parameter estimates. Force-fitting of parameters was not done in order to examine the realtime behavior of particle populations in wet grinding systems. Breakage functions were established as being invariant with respect to such operating variables like ball load, mill speed, particle load, and particle size distribution of the mill. It was also determined that specific selection functions were inherently dependent on the particle size distribution in wet grinding systems. Also, they were consistent with inputs of specific energy, according to grind time. Nonlinearity trends were observed for 1st order specific selection functions which illustrated variations in breakage rates with incremental inputs of grind time and specific energy. A mean particle size called the fulcrum was noted below which the nonlinearities in the breakage trends were observed. This magnitude of the fulcrum value varied with percent solids and slurry filling, indicating

Effect of simulated chairside grinding procedures using commercially available abrasive agents on the surface properties of zirconia.

Science.gov (United States)

Sandhu, Ramandeep; Kheur, Mohit; Kheur, Supriya

2017-01-01

The aim of the present study was to assess the change in physical properties (surface roughness, surface hardness and phase transformation) after surface grinding of zirconia by using three commercially available abrasives. Thirty sintered zirconia specimens were prepared and divided into three groups namely Group M (grinded using Mani Dia diamond bur standard grit), Group T (grinded using Tri Hawk diamond bur coarse grit) and Group P (grinded using Predator carbide bur). A customised assembly was used to follow a standardised protocol for surface grinding. The surface roughness, surface hardness and phase transformation was recorded before and after the grinding procedure. ANOVA and Bonferroni post hoc test were used to assess the values obtained after the testing the surface roughness and surface hardness. The results of the present study revealed the average values of change in surface roughness as Group M (0.44 μ m) and Group T (1.235 μ m) and Group P (-0.88 μ m). The average values of change in surface hardness were Group T (19.578 HV), Group M (46.722 HV) and Group P (36.429 HV). The change in surface hardness was not statistically significant. There was no phase transformation seen after the grinding procedure. Carbide burs along with copious water irrigation when used to grind zirconia intra-orally produces has a polishing effect, minimal change in hardness & no phase transformation. The present study advocates the use of carbides for chair-side grinding of zirconia.

Treatment of the Bleaching Effluent from Sulfite Pulp Production by Ceramic Membrane Filtration

OpenAIRE

Ebrahimi, Mehrdad; Busse, Nadine; Kerker, Steffen; Schmitz, Oliver; Hilpert, Markus; Czermak, Peter

2015-01-01

Pulp and paper waste water is one of the major sources of industrial water pollution. This study tested the suitability of ceramic tubular membrane technology as an alternative to conventional waste water treatment in the pulp and paper industry. In this context, in series batch and semi-batch membrane processes comprising microfiltration, ultrafiltration and nanofiltration, ceramic membranes were developed to reduce the chemical oxygen demand (COD) and remove residual lignin from the effluen...

Processing and properties of large-sized ceramic slabs

Energy Technology Data Exchange (ETDEWEB)

Raimondo, M.; Dondi, M.; Zanelli, C.; Guarini, G.; Gozzi, A.; Marani, F.; Fossa, L.

2010-07-01

Large-sized ceramic slabs with dimensions up to 360x120 cm{sup 2} and thickness down to 2 mm are manufactured through an innovative ceramic process, starting from porcelain stoneware formulations and involving wet ball milling, spray drying, die-less slow-rate pressing, a single stage of fast drying-firing, and finishing (trimming, assembling of ceramic-fiberglass composites). Fired and unfired industrial slabs were selected and characterized from the technological, compositional (XRF, XRD) and microstructural (SEM) viewpoints. Semi-finished products exhibit a remarkable microstructural uniformity and stability in a rather wide window of firing schedules. The phase composition and compact microstructure of fired slabs are very similar to those of porcelain stoneware tiles. The values of water absorption, bulk density, closed porosity, functional performances as well as mechanical and tribological properties conform to the top quality range of porcelain stoneware tiles. However, the large size coupled with low thickness bestow on the slab a certain degree of flexibility, which is emphasized in ceramic-fiberglass composites. These outstanding performances make the large-sized slabs suitable to be used in novel applications: building and construction (new floorings without dismantling the previous paving, ventilated facades, tunnel coverings, insulating panelling), indoor furnitures (table tops, doors), support for photovoltaic ceramic panels. (Author) 24 refs.

Processing and properties of large-sized ceramic slabs

International Nuclear Information System (INIS)

Raimondo, M.; Dondi, M.; Zanelli, C.; Guarini, G.; Gozzi, A.; Marani, F.; Fossa, L.

2010-01-01

Large-sized ceramic slabs with dimensions up to 360x120 cm 2 and thickness down to 2 mm are manufactured through an innovative ceramic process, starting from porcelain stoneware formulations and involving wet ball milling, spray drying, die-less slow-rate pressing, a single stage of fast drying-firing, and finishing (trimming, assembling of ceramic-fiberglass composites). Fired and unfired industrial slabs were selected and characterized from the technological, compositional (XRF, XRD) and microstructural (SEM) viewpoints. Semi-finished products exhibit a remarkable microstructural uniformity and stability in a rather wide window of firing schedules. The phase composition and compact microstructure of fired slabs are very similar to those of porcelain stoneware tiles. The values of water absorption, bulk density, closed porosity, functional performances as well as mechanical and tribological properties conform to the top quality range of porcelain stoneware tiles. However, the large size coupled with low thickness bestow on the slab a certain degree of flexibility, which is emphasized in ceramic-fiberglass composites. These outstanding performances make the large-sized slabs suitable to be used in novel applications: building and construction (new floorings without dismantling the previous paving, ventilated facades, tunnel coverings, insulating panelling), indoor furnitures (table tops, doors), support for photovoltaic ceramic panels. (Author) 24 refs.

Mathematical simulation of bearing ring grinding process

Science.gov (United States)

Koltunov, I. I.; Gorbunova, T. N.; Tumanova, M. B.

2018-03-01

The paper suggests the method of forming a solid finite element model of the bearing ring. Implementation of the model allowed one to evaluate the influence of the inner cylindrical surface grinding scheme on the ring shape error.

Effect of simulated chairside grinding procedures using commercially available abrasive agents on the surface properties of zirconia

OpenAIRE

Sandhu, Ramandeep; Kheur, Mohit; Kheur, Supriya

2017-01-01

Aim: The aim of the present study was to assess the change in physical properties (surface roughness, surface hardness and phase transformation) after surface grinding of zirconia by using three commercially available abrasives. Materials and Methods: Thirty sintered zirconia specimens were prepared and divided into three groups namely Group M (grinded using Mani Dia diamond bur standard grit), Group T (grinded using Tri Hawk diamond bur coarse grit) and Group P (grinded using Predator car...

Investigation on Surface Roughness in Cylindrical Grinding

Science.gov (United States)

Rudrapati, Ramesh; Bandyopadhyay, Asish; Pal, Pradip Kumar

2011-01-01

Cylindrical grinding is a complex machining process. And surface roughness is often a key factor in any machining process while considering the machine tool or machining performance. Further, surface roughness is one of the measures of the technological quality of the product and is a factor that greatly influences cost and quality. The present work is related to some aspects of surface finish in the context of traverse-cut cylindrical grinding. The parameters considered have been: infeed, longitudinal feed and work speed. Taguchi quality design is used to design the experiments and to identify the significantly import parameter(s) affecting the surface roughness. By utilization of Response Surface Methodology (RSM), second order differential equation has been developed and attempts have also been made for optimization of the process in the context of surface roughness by using C- programming.

Task-specific noise exposure during manual concrete surface grinding in enclosed areas-influence of operation variables and dust control methods.

Science.gov (United States)

Akbar-Khanzadeh, Farhang; Ames, April L; Milz, Sheryl A; Akbar-Khanzadeh, Mahboubeh

2013-01-01

Noise exposure is a distinct hazard during hand-held concrete grinding activities, and its assessment is challenging because of the many variables involved. Noise dosimeters were used to examine the extent of personal noise exposure while concrete grinding was performed with a variety of grinder sizes, types, accessories, and available dust control methods. Noise monitoring was conducted in an enclosed area covering 52 task-specific grinding sessions lasting from 6 to 72 minutes. Noise levels, either in minute average noise level (Lavg, dBA) or in minute peak (dBC), during concrete grinding were significantly (P grinding cup wheel (blade) sizes of 4-inch (100 mm), 5-inch (125 mm) and 6-inch (150 mm), and surface orientation (horizontal, inclined). Overall, minute Lavg during grinding was 97.0 ± 3.3 (mean ± SD), ranging from 87.9 to 113. The levels of minute Lavg during uncontrolled grinding (98.9 ± 5.2) or wet-grinding (98.5 ± 2.7) were significantly higher than those during local exhaust ventilation (LEV) grinding (96.2 ± 2.8). A 6-inch grinding cup wheel generated significantly higher noise levels (98.7 ± 2.8) than 5-inch (96.3 ± 3.2) or 4-inch (95.3 ± 3.5) cup wheels. The minute peak noise levels (dBC) during grinding was 113 ± 5.2 ranging from 104 to 153. The minute peak noise levels during uncontrolled grinding (119 ± 10.2) were significantly higher than those during wet-grinding (115 ± 4.5) and LEV-grinding (112 ± 3.4). A 6-inch grinding cup wheel generated significantly higher minute peak noise levels (115 ± 5.3) than 5-inch (112 ± 4.5) or 4-inch (111 ± 5.4) cup wheels. Assuming an 8-hour work shift, the results indicated that noise exposure levels during concrete grinding in enclosed areas exceeded the recommended permissible exposure limits and workers should be protected by engineering control methods, safe work practices, and/or personal protective devices.

On-machine measurement of the grinding wheels' 3D surface topography using a laser displacement sensor

Science.gov (United States)

Pan, Yongcheng; Zhao, Qingliang; Guo, Bing

2014-08-01

A method of non-contact, on-machine measurement of three dimensional surface topography of grinding wheels' whole surface was developed in this paper, focusing on an electroplated coarse-grained diamond grinding wheel. The measuring system consists of a Keyence laser displacement sensor, a Keyence controller and a NI PCI-6132 data acquisition card. A resolution of 0.1μm in vertical direction and 8μm in horizontal direction could be achieved. After processing the data by LabVIEW and MATLAB, the 3D topography of the grinding wheel's whole surface could be reconstructed. When comparing the reconstructed 3D topography of the grinding wheel's marked area to its real topography captured by a high-depth-field optical digital microscope (HDF-ODM) and scanning electron microscope (SEM), they were very similar to each other, proving that this method is accurate and effective. By a subsequent data processing, the topography of every grain could be extracted and then the active grain number, the active grain volume and the active grain's bearing ration could be calculated. These three parameters could serve as the criterion to evaluate the grinding performance of coarse-grained diamond grinding wheels. Then the performance of the grinding wheel could be evaluated on-machine accurately and quantitatively.

PENGARUH GUGUS p-METOKSI PADA REAKSI KONDENSASI CLAYSEN-SCHMIDT MENGGUNAKAN METODA GRINDING

Directory of Open Access Journals (Sweden)

Karim Theresih

2016-10-01

  This research aims to synthesize the compound dibenzalaceton, 4-methoksikalkon and dianisalaceton through Claysen Schmidt condensation reaction with grinding method and to determine the effect of p-methoxy groups on the reaction. Dibenzalaceton compound was synthesized from benzaldehyde, acetone, and NaOH. Synthesis of compound 4-metoksikhalkon was done using 4-methoxybenzaldehyde, acetophenone, and NaOH. Dianisalceton compound was synthesized through Claysen-schmidt reaction between acetone, anisaldehide, and the catalysts NaOH. This synthesis were performed through solvent-free grinding method. Catalyst base material and simultaneously crushed in mortar for 15 minutes to form a paste. The pasta is dried and recrystallized. The resulted compounds were characterized by TLC, FTIR and GC-MS. Based on the results of the analysis of FTIR and GC-MS showed that dibenzalaceton, 4-methoksikhalkon and dianisalaceton can be synthesized and have succession yield 59.93%, 86.21% and 70.39% . There is the influence of p-methoxy groups in a condensation reaction Claysen-Schmidt on the synthesis of compounds dibenzalaceton, 4-methoksikhalkon and dianizalaceton use grinding method.   Keywords: dibenzalaceton, 4-methoksikhalkon, dianizalaceton, grinding method

Possibilities of Pelletizing and Briquetting of Dusts from Castings Grinding

Directory of Open Access Journals (Sweden)

A. Pribulová

2010-04-01

Full Text Available Foundry dust can be divided into three groups: metallic dust with Fe content over 70%, mixed dust with Fe or SiO2 content between 10 –70% and sand wastes with minimum content of SiO2 about 70%. Dust from castings grinding with high Fe content (87.9% is still landfillin Slovakia. The aim of experiments with dust from grinding has been to find the cheapest way of dust agglomeration with minimumamount of binder because of melting in the electric induction furnace. The dust was pelletized and briquetted and as binders bentonite, water glass and cement were used. Briquettes made from dust from grinding with addition of water glass got compression strength after three months on the air about 82 kPa. Briquettes with addition of water glass were melted together with cast iron in electric induction furnace. Yield of metal from briquettes was around 80% and slag quantity around 4% (without briquettes the slag quantity was 1.4%.

Effect of disintegration wave grinding on fractional protein and amino acid composition of chickpea

Directory of Open Access Journals (Sweden)

G. O. Magomedov

2013-01-01

Full Text Available The study of fractional changes and amino acid composition of proteins in the application of chickpea disintegration wave grinding. Comparative analysis of six varieties of chickpea before and after grinding.

Effects of metal surface grinding at the porcelain try-in stage of fixed dental prostheses.

Science.gov (United States)

Kılınç, Halil İbrahim; Kesim, Bülent; Gümüş, Hasan Önder; Dinçel, Mehmet; Erkaya, Selçuk

2014-08-01

This study was to evaluate the effect of grinding of the inner metal surface during the porcelain try-in stage on metal-porcelain bonding considering the maximum temperature and the vibration of samples. Ninety-one square prism-shaped (1 × 1 × 1.5 mm) nickel-chrome cast frameworks 0.3 mm thick were prepared. Porcelain was applied on two opposite outer axial surfaces of the frameworks. The grinding was performed from the opposite axial sides of the inner metal surfaces with a low-speed handpiece with two types of burs (diamond, tungsten-carbide) under three grinding forces (3.5 N, 7 N, 14 N) and at two durations (5 seconds, 10 seconds). The shear bond strength (SBS) test was performed with universal testing machine. Statistical analyzes were performed at 5% significance level. The samples subjected to grinding under 3.5 N showed higher SBS values than those exposed to grinding under 7 N and 14 N (P.05). The types of bur (P=.965) and the duration (P=.679) did not affect the SBS values. On the other hand, type of bur, force applied, and duration of the grinding affected the maximum temperatures of the samples, whereas the maximum vibration was affected only by the type of bur (PGrinding the inner metal surface did not affect the metal-porcelain bond strength. Although the grinding affected the maximum temperature and the vibration values of the samples, these did not influence the bonding strength.

Incidence of Ceramic Liner Malseating After Ceramic-on-Ceramic Total Hip Arthroplasty Associated With Osteolysis: A 5- to 15-Year Follow-Up Study.

Science.gov (United States)

Higuchi, Yoshitoshi; Hasegawa, Yukiharu; Komatsu, Daigo; Seki, Taisuke; Ishiguro, Naoki

2017-05-01

The aim of our study was to evaluate the clinical and radiographic outcomes of malseating of the acetabular liner in ceramic-on-ceramic total hip arthroplasty (THA). Outcomes for 160 ceramic-on-ceramic THAs, contributed by 116 women and 39 men, were evaluated. Clinical and radiographic measurements were obtained over a 5- to 15-year follow-up for analysis. Liner malseating was identified in 20% of cases. Outcomes for 32 cases with liner malseating (group A) were compared to outcomes for 128 joints with correct liner seating (group B). The Harris hip score at the last follow-up was 90.1 for group A and 89.6 for group B. Osteolysis was identified in 5 cases in group A (15.6%), compared to 3 cases in group B (P ceramic fracture, audible squeaking, loosening of components, and revision THA. The mean annual liner wear rate was comparable between groups, 0.0045 mm/y for group A and 0.0039 mm/y for group B. The 10-year Kaplan-Meier survivorship, based on an end point of revision THA, was 100% for group A and 99.0% for group B. Over a moderate-length follow-up of 5-15 years, malseating of the acetabular liner was not associated with negative clinical outcomes or THA survivorship. Malseating did increase the incidence of osteolysis, a risk factor for adverse effects. Long-term follow-up studies are needed to fully quantify the effects of malseating of the acetabular liner. Copyright © 2016 Elsevier Inc. All rights reserved.

Reducing the Entrainment of Gangue Fines in Low Grade Microcrystalline Graphite Ore Flotation Using Multi-Stage Grinding-Flotation Process

Directory of Open Access Journals (Sweden)

Xiaoqing Weng

2017-03-01

Full Text Available A suitable grinding fineness and flow-sheet could potentially reduce the mechanical entrainment of gangue minerals in the flotation process of microcrystalline graphite. In this study, the suitable grinding fineness of a commercial graphite ore was estimated by mineralogy analysis and laboratory grind-flotation tests. The target grind size of this ore should be 92% passing 74 μm based on the mineralogical evaluation and the flotation performance. A comparison of a single-stage and a three-stage grinding circuit was conducted. Experimental results demonstrated that the three-stage grinding circuit could effectively improve the separation effect, which was attributed to the reduction of slimes. In the end, a more desirable beneficiation result was obtained with the application of three-stage grinding-flotation process by minimizing gangue entrainment.

Grinding of WC-Co hard-metals

NARCIS (Netherlands)

Hegeman, J.B.J.W.; Hosson, de J.Th.M.; With, de G.

2001-01-01

Morphol. of ground surface of WC-Co cermets with 10 and 20% Co was studied. A deformed and detached surface layer was found on top of the specimens after surface grinding with a diamond wheel. Etching the surface layer revealed WC grains in the subsurface of the machined specimens. Most of these

Production of coloured glass-ceramics from incinerator ash using thermal plasma technology.

Science.gov (United States)

Cheng, T W; Huang, M Z; Tzeng, C C; Cheng, K B; Ueng, T H

2007-08-01

Incineration is a major treatment process for municipal solid waste in Taiwan. It is estimated that over 1.5 Mt of incinerator ash are produced annually. This study proposes using thermal plasma technology to treat incinerator ash. Sintered glass-ceramics were produced using quenched vitrified slag with colouring agents added. The experimental results showed that the major crystalline phases developed in the sintered glass-ceramics were gehlenite and wollastonite, but many other secondary phases also appeared depending on the colouring agents added. The physical/mechanical properties, chemical resistance and toxicity characteristic leaching procedure of the coloured glass-ceramics were satisfactory. The glass-ceramic products obtained from incinerator ash treated with thermal plasma technology have great potential for building applications.

Annual, semi-annual and ter-annual variations of gravity wave momentum flux in 13 years of SABER data

Science.gov (United States)

Chen, Dan; Preusse, Peter; Ern, Manfred; Strube, Cornelia

2017-04-01

In this study, the variations at different time scales such as the annual cycle, the semiannual oscillation (SAO), the ter-annual cycle (about four monthly) and the quasi-biennial oscillation (QBO) in zonal mean GW amplitudes and GW momentum flux (GWMF) have been investigated using satellite observations from 2002-2014 and combining ECMWF high resolution data with the GORGRAT model. The global distribution (patterns) of spectral amplitudes of GW momentum flux in stratosphere and mesosphere (from 30 km to 90 km) show that the annual cycle is the most predominant variation, and then are SAO, ter-annual cycle and QBO. For annual components, two relatively isolated amplitude maxima appear in each hemisphere: a subtropical maximum is associated with convective sources in summer, a mid and high latitude maximum is associated with the polar vortex in winter. In the subtropics, GWs propagate upward obliquely to the higher latitudes. The winter maximum in the southern hemisphere has larger momentum flux than that one in the northern hemisphere. While on the SH the phase (i.e. time corresponding to the maximum GWMF) continuously descends with the maximum in July in the upper mesosphere and in September in the lower stratosphere, on the northern hemisphere, the phase has no visible altitude dependence with a maximum in December. For semiannual variations, in the MLT (70-80 km) region, there is an obvious enhancement of spectral amplitude at equatorial latitudes which relate to the dissipation of convectively forced GWs. The SAO in absolute momentum flux and the annual cycle in zonal momentum flux indicated that the variations at mid-latitudes (about from 30°-40°) are not a SAO signals but rather an annual cycle when the direction of GWMF is considered. The ter-annual cycle may be related to the duration of active convection in subtropical latitudes (from June to Sep. in north hemisphere) Indications for QBO are found latitude extension to mid-latitudes in stratosphere of

Diamond blade grinding as a means for removing surface contamination from concrete

International Nuclear Information System (INIS)

Lynch, T.W.

1980-01-01

The use of a highway grinding unit for the decontamination of a 5,000 square foot surface is described. The type of equipment presently in use is described. Performance characteristics, waste collection and water usage are commented on. Variables in blade design are discussed. Feasibility of the grinding technique for water soluble contaminants and vertical surfaces is referred to

A method of detection to the grinding wheel layer thickness based on computer vision

Science.gov (United States)

Ji, Yuchen; Fu, Luhua; Yang, Dujuan; Wang, Lei; Liu, Changjie; Wang, Zhong

2018-01-01

This paper proposed a method of detection to the grinding wheel layer thickness based on computer vision. A camera is used to capture images of grinding wheel layer on the whole circle. Forward lighting and back lighting are used to enables a clear image to be acquired. Image processing is then executed on the images captured, which consists of image preprocessing, binarization and subpixel subdivision. The aim of binarization is to help the location of a chord and the corresponding ring width. After subpixel subdivision, the thickness of the grinding layer can be calculated finally. Compared with methods usually used to detect grinding wheel wear, method in this paper can directly and quickly get the information of thickness. Also, the eccentric error and the error of pixel equivalent are discussed in this paper.

Study on the Optimization and Process Modeling of the Rotary Ultrasonic Machining of Zerodur Glass-Ceramic

Science.gov (United States)

Pitts, James Daniel

Rotary ultrasonic machining (RUM), a hybrid process combining ultrasonic machining and diamond grinding, was created to increase material removal rates for the fabrication of hard and brittle workpieces. The objective of this research was to experimentally derive empirical equations for the prediction of multiple machined surface roughness parameters for helically pocketed rotary ultrasonic machined Zerodur glass-ceramic workpieces by means of a systematic statistical experimental approach. A Taguchi parametric screening design of experiments was employed to systematically determine the RUM process parameters with the largest effect on mean surface roughness. Next empirically determined equations for the seven common surface quality metrics were developed via Box-Behnken surface response experimental trials. Validation trials were conducted resulting in predicted and experimental surface roughness in varying levels of agreement. The reductions in cutting force and tool wear associated with RUM, reported by previous researchers, was experimentally verified to also extended to helical pocketing of Zerodur glass-ceramic.

Chemical and ceramic methods toward safe storage of actinides using monazite. 1998 annual progress report

International Nuclear Information System (INIS)

Boatner, L.A.; Morgan, P.E.D.

1998-01-01

'The use of ceramic monazite, (La,Ce)PO 4 , for sequestering actinides, especially plutonium, and some other radioactive waste elements (rare earths e.g.) and thus isolating them from the environment has been championed by Lynn Boatner of ORNL. It may be used alone or, as it is compatible with many other minerals in nature, can be used in composite combinations. Natural monazite, which almost invariably contains Th and U, is often formed in hydrothermal pegmatites and is extremely water resistant--examples are known where the mineral has been washed out of rocks (becoming a placer mineral as on the beach sands of India, Australia, Brazil etc.) then reincorporated into new rocks with new crystal overgrowths and then washed out again--being 2.5--3 billion years old. During this demanding water treatment it has retained Th and U. Where very low levels of water attack have been seen (in more siliceous waters), the Th is tied up as new ThSiO 4 and remains immobile. Lest it be thought that rare-earths are rare or expensive, this is not so. In fact, the less common lanthanides such as gadolinium, samarium, europium, and terbium, are necessarily extracted and much used by, e.g., the electronics industry, leaving La and Ce as not-sufficiently-used by-products. The recent development of large scale use of Nd in Nd-B-Fe magnets has further exaggerated this. Large deposits of the parent mineral bastnaesite are present in the USA and in China. (Mineral monazite itself is not preferred due to its thorium content.) In the last 5 years it has become apparent show that monazite (more specifically La-monazite) is an unrecognized/becoming-interesting ceramic material. PuPO4 itself has the monazite structure; the PO 4 3-unit strongly stabilizes actinides and rare earths in their trivalent state. Monazite melts without decomposition (in a closed system) at 2,074 C and, being compatible with common ceramic oxides such as alumina, mullite, zirconia and YAG, is useful in oxidatively

The effect of wheel eccentricity and run-out on grinding forces, waviness, wheel wear and chatter

OpenAIRE

O'DONNELL, GARRET; MURPHY, STUART

2011-01-01

PUBLISHED The effect of grinding-wheel eccentricity on grinding forces, wheel wear and final waviness height was studied. Eccentricity was evident in force oscillations and acceleration and audio measurements. A model was developed to predict final scallop-profile shape from grinding parameters and eccentricity. Recommendations are given on detecting eccentricity and determining when eccentricity is tolerable.

Effect of cryogenic grinding on volatile and fatty oil constituents of cumin (Cuminum cyminum L.) genotypes.

Science.gov (United States)

Sharma, L K; Agarwal, D; Rathore, S S; Malhotra, S K; Saxena, S N

2016-06-01

Effect of cryogenic grinding on recovery of volatile oil, fatty oil percentage and their constituents in two cumin (Cuminum cyminum L.) genotypes have been analyzed. Cryogenic grinding not only retains the volatiles but enhanced the recovery by 33.9 % in GC 4 and 43.5 % in RZ 209. A significant increase (29.9 %) over normal grinding in oil percentage was also observed in genotype RZ 209. This increase was, however, less (15.4 %) in genotype GC 4. Nineteen major compounds were identified in the essential oil of both genotypes. The two grinding techniques had significant effects on dependent variables, viz., volatile oil and monoterpenes. Cuminaldehyde was the main constituent in both genotypes, content of which increased from 48.2 to 56.1 % in GC 4 on cryo grinding. Content of terpines were found to decrease in cryo ground samples of GC 4 and either decrease or no change was found in RZ 209. Organoleptic test showed more pleasant aroma in cryo ground seeds of both the genotypes. Significant increase was also reported in fatty oil yield due to cryogenic grinding. Fatty acid methyl ester (FAME) analysis showed oleic acid as major FAME content of which increased from 88.1 to 94.9 % in RZ 209 and from 88.2 to 90.1 % in GC 4 on cryogenic grinding. Other prominent FAME were palmitic, palmitoleic and stearic acid. Results indicated commercial potential of cryogenic grinding technology for cumin in general and spices in particular for better retention of flavour and quality in spices.

Semi-annual report of the Department of Energy, Office of Environmental Management, Quality Assessment Program

International Nuclear Information System (INIS)

Greenlaw, P.D.

1998-01-01

This Quality Assessment Program (QAP) is designed to test the quality of the environmental measurements being reported to the Department of Energy by its contractors. Since 1976, real or synthetic environmental samples that have been prepared and thoroughly analyzed at the Environmental Measurements Laboratory (EML) have been distributed at first quarterly and then semi-annually to these contractors. Their results, which are returned to EML within 90 days, are compiled with EML's results and are reported back to the participating contractors 30 days later. A summary of the reported results is available to the participants 4 days after the reporting deadline via the Internet at www.eml.doe.gov. This report presents the results from the analysis of the 47th set of environmental quality assessment samples (QAP XLVII) that were received on or before December 1, 1997

Westinghouse modular grinding process - improvement for follow on processes

Energy Technology Data Exchange (ETDEWEB)

Fehrmann, Henning [Westinghouse Germany GmbH, Mannheim, State (Germany)

2013-07-01

In nuclear power plants (NPP) ion exchange (IX) resins are used in several systems for water treatment. The resins can be in bead or powdered form. For waste treatment of spent IX resins, two methods are basically used: Direct immobilization (e.g. with cement, bitumen, polymer or High Integrity Container (HIC)); Thermal treatment (e.g. drying, oxidation or pyrolysis). Bead resins have some properties (e.g. particle size and density) that can have negative impacts on following waste treatment processes. Negative impacts could be: Floatation of bead resins in cementation process; Sedimentation in pipeline during transportation; Poor compaction properties for Hot Resin Supercompaction (HRSC). Reducing the particle size of the bead resins can have beneficial effects enhancing further treatment processes and overcoming prior mentioned effects. Westinghouse Electric Company has developed a modular grinding process to crush/grind the bead resins. This modular process is designed for flexible use and enables a selective adjustment of particle size to tailor the grinding system to the customer needs. The system can be equipped with a crusher integrated in the process tank and if necessary a colloid mill. The crusher reduces the bead resins particle size and converts the bead resins to a pump able suspension with lower sedimentation properties. With the colloid mill the resins can be ground to a powder. Compared to existing grinding systems this equipment is designed to minimize radiation exposure of the worker during operation and maintenance. Using the crushed and/or ground bead resins has several beneficial effects like facilitating cementation process and recipe development, enhancing oxidation of resins, improving the Hot Resin Supercompaction volume reduction performance. (authors)

Westinghouse modular grinding process - improvement for follow on processes

International Nuclear Information System (INIS)

Fehrmann, Henning

2013-01-01

In nuclear power plants (NPP) ion exchange (IX) resins are used in several systems for water treatment. The resins can be in bead or powdered form. For waste treatment of spent IX resins, two methods are basically used: Direct immobilization (e.g. with cement, bitumen, polymer or High Integrity Container (HIC)); Thermal treatment (e.g. drying, oxidation or pyrolysis). Bead resins have some properties (e.g. particle size and density) that can have negative impacts on following waste treatment processes. Negative impacts could be: Floatation of bead resins in cementation process; Sedimentation in pipeline during transportation; Poor compaction properties for Hot Resin Supercompaction (HRSC). Reducing the particle size of the bead resins can have beneficial effects enhancing further treatment processes and overcoming prior mentioned effects. Westinghouse Electric Company has developed a modular grinding process to crush/grind the bead resins. This modular process is designed for flexible use and enables a selective adjustment of particle size to tailor the grinding system to the customer needs. The system can be equipped with a crusher integrated in the process tank and if necessary a colloid mill. The crusher reduces the bead resins particle size and converts the bead resins to a pump able suspension with lower sedimentation properties. With the colloid mill the resins can be ground to a powder. Compared to existing grinding systems this equipment is designed to minimize radiation exposure of the worker during operation and maintenance. Using the crushed and/or ground bead resins has several beneficial effects like facilitating cementation process and recipe development, enhancing oxidation of resins, improving the Hot Resin Supercompaction volume reduction performance. (authors)

Grinding of Inconel 713 superalloy for gas turbines

Czech Academy of Sciences Publication Activity Database

Čapek, J.; Kyncl, J.; Kolařík, K.; Beránek, L.; Pitrmuc, Z.; Medřický, Jan; Pala, Z.

2016-01-01

Roč. 16, č. 1 (2016), s. 14-15 ISSN 1213-2489 Institutional support: RVO:61389021 Keywords : Casting defects * Gas turbine * Grinding * Nickel superalloy * Residual stresses Subject RIV: JJ - Other Materials

Sodium-ion transfer at the interface between ceramic and organic electrolytes

Energy Technology Data Exchange (ETDEWEB)

Sagane, Fumihiro; Abe, Takeshi; Ogumi, Zempachi [Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510 (Japan)

2010-11-01

Sodium-ion transfer through the interface between ceramic and organic electrolytes was studied by AC impedance spectroscopy. Na{sub 3}Zr{sub 1.88}Y{sub 0.12}Si{sub 2}PO{sub 12} (NASICON) and Na-{beta}''-alumina were used as ceramic electrolytes, and propylene carbonate (PC) and dimethyl sulfoxide (DMSO) containing 0.05 mol dm{sup -3} NaCF{sub 3}SO{sub 3} were used as organic electrolytes. The semi-circle ascribed to interfacial charge transfer resistance (R{sub ct}) was observed. The activation energies for sodium-ion transfer at the interface between ceramic and organic electrolytes were evaluated by the temperature dependency of R{sub ct}. As a result, the activation energies depended on the ceramic electrolytes but not on the solvents. These results suggest that sodium-ion transfer from ceramic to organic electrolytes should be responsible for the activation energies, which is contrary to the case in a lithium-ion transfer system. Based on these results, the mechanism of interfacial sodium-ion transfer was discussed. (author)

Analysis of cement superplasticizers and grinding aids a literature survey

International Nuclear Information System (INIS)

Ervanne, H.; Hakanen, M.

2007-04-01

This literature survey reviews the methods for analysis of cement plasticizers and organic grounding aids in cement solutions in preparation of grouts/concrete and methods for determination of plasticizers and grinding aids in groundwater conditions. The survey focuses on three different types of superplasticizers: sulphonated naphthalene condensates, sulphonated melamine condensates and polycarboxylates. There are various organic grinding aids, such as alkanolamines, glycols or phenolic compounds, used in the cement industry. This review is concerned with the following compounds: triethylenetetramine, tetraethylenepentamine, diethanolamine, triethanolamine, triisopropanolamine, ethyleneglycol, diethyleneglycol, aminoethylethanolamine, hydroxyethyl diethylenetriamine and phenol. (orig.)

The effect of structurally related impurities on crystallinity reduction of sulfamethazine by grinding.

Science.gov (United States)

Hamada, Yoshito; Ono, Makoto; Ohara, Motomu; Yonemochi, Etsuo

2016-12-30

In this study, the effect of structurally related impurities on crystallinity reduction of sulfamethazine by grinding was evaluated. The crystallinity of sulfamethazine was not decreased when it was ground alone. However, when structurally related impurities with sulfonamide derivatives were blended, the crystallinity of sulfamethazine was decreased by grinding. Other materials without a sulfonamide moiety showed no such effect. The Raman spectra of sulfamethazine demonstrated that there was a difference between its crystalline and amorphous states within its sulfonamide structure. It was suggested that the sulfonamide structure of the impurities was important in causing the inhibition of recrystallization of sulfamethazine during grinding. Copyright © 2016 Elsevier B.V. All rights reserved.

Radiometric measurement of ceramic material moisture

International Nuclear Information System (INIS)

Kominek, A.; Sojka, J.; Votava, P.

1975-01-01

Water content measurement using a neutron moisture meter has a long tradition in the CSSR. The method of water content determination using neutron and gamma radiation was developed by the Research Institute of Building Materials in Brno for a number of materials, as e.g. coke, brown coal semi-coke, anthracite, glass sand, dolomite, soda, gravel, aggregates, cement sludge, slag, brick clay, intermediate products of the ceramics industry, refractory building materials, etc. The water content measurement of ceramic materials for the manufacture of wall tiles was performed in a special equipment by detection of the slowed-down neutrons with an accuracy of +-0.6% water (within the range from 5 to 11%) and of materials for the manufacture of floor tiles by means of neutron and gamma radiation with an accuracy of +-0.4% water (within the range from 5 to 8%). (author)

Effect of grinding and polishing on roughness and strength of zirconia.

Science.gov (United States)

Khayat, Waad; Chebib, Najla; Finkelman, Matthew; Khayat, Samer; Ali, Ala

2018-04-01

The clinical applications of high-translucency monolithic zirconia restorations have increased. Chairside and laboratory adjustments of these restorations are inevitable, which may lead to increased roughness and reduced strength. The influence of grinding and polishing on high-translucency zirconia has not been investigated. The purpose of this in vitro study was to compare the roughness averages (Ra) of ground and polished zirconia and investigate whether roughness influenced strength after aging. High-translucency zirconia disks were milled, sintered, and glazed according to the manufacturer's recommendations. Specimens were randomized to 4 equal groups. Group G received only grinding; groups GPB and GPK received grinding and polishing with different polishing systems; and group C was the (unground) control group. All specimens were subjected to hydrothermal aging in an autoclave at 134°C at 200 kPa for 3 hours. Roughness average was measured using a 3-dimensional (3D) optical interferometer at baseline (Ra1), after grinding and polishing (Ra2), and after aging (Ra3). A biaxial flexural strength test was performed at a rate of 0.5 mm/min. Statistical analyses were performed using commercial software (α=.05). Group G showed a significantly higher mean value of Ra3 (1.96 ±0.32 μm) than polished and glazed groups (P.05). Compared with baseline, the roughness of groups G and GPB increased significantly after surface treatments and after aging, whereas aging did not significantly influence the roughness of groups GPK or C. Group G showed the lowest mean value of biaxial flexural strength (879.01 ±157.99 MPa), and the highest value was achieved by group C (962.40 ±113.84 MPa); no statistically significant differences were found among groups (P>.05). Additionally, no significant correlation was detected between the Ra and flexural strength of zirconia. Grinding increased the roughness of zirconia restorations, whereas proper polishing resulted in smoothness

A novel method of freeform surface grinding with a soft wheel based on industrial robots

Science.gov (United States)

Sha, Sheng-chun; Guo, Xiao-ling

2011-08-01

In order to meet the growing demand for high-quality images, optical elements of freeform surface are more and more applied to imaging system. However the fabrication of freeform surface optical elements is much more difficult than that of traditional spherical ones. Recent research on freeform surface manufacture often deals with precision machine tools which have limitations on dimensions and are always expensive. Little has been researched on industrial robots. In this paper, a new method of freeform surface grinding based on industrial robots was found. This method could be applied to both whole surface grinding as well as partial surface grinding. The diameter of lenses to be ground would not be restricted to the machine tool's size. In this method a high-speed-rotating soft wheel was used. The relation between removing amount and grinding time which could be called removing function was established and measured. The machining precision was achieved by means of controlling the grinding time instead of the machine tool or industrial robot itself. There are two main factors affecting the removing function: i).rotating speed of the soft wheel; ii).pressure between the wheel and the work piece. In this paper, two groups of experiments have been conducted. One is the removing function tested at constant rotating speed while under different pressure. The other is that tested under a certain pressure with variable speed. Tables and curves which can show the effect of speed and pressure on the removing efficiency have been obtained. Cause for inaccuracy between experiment data and calculated result according to the theory and the non-linearity in the curves was analyzed. Through these analyses the removing function could be concluded under certain condition including rotating speed and pressure. Finally several experiments were performed to verify the appropriateness of the removing function. It could also be concluded that this method was more efficient in comparison

Optimization of Process Variables for Grinding of Ibuprofen using Response Surface Methodology

International Nuclear Information System (INIS)

Sim, Chol-Ho

2013-01-01

Ibuprofen, non-steroidal anti-inflammatory drugs; NSAIDs, is a highly crystalline substance with the pharmaceutical properties of poor solubility and low bioavailability. The size reduction of ibuprofen is needed to improve the solubility. The objective of this study is to optimize the grinding condition of ibuprofen. Grinding of ibuprofen was carried out using a planetary mill. Grinding parameters were optimized using Box-Behnken experimental design method. The physical characteristics of ground ibuprofen were investigated for the particle size by particle size analyzer, for the crystal size by X-ray diffraction (XRD), and for the tensile strength by tensile/compression tester. The optimum conditions for the milling of ibuprofen were 290 rpm of the revolution number of mill, 24.6 g of the weight of sample, and 10minutes of grinding time. The measured value of the particle size of ground ibuprofen at these optimum conditions was 13.5 µm. The results showed that the crystal size of ibuprofen was reduced by the planetary milling process. In case the relative density of the tablets formulated of ground ibuprofen was range of 0.85-0.90, the tensile strength of them was range of 12-14 Kg f /cm 2

Effect of Grinding on Chrysotile, Amosite and Crocidolite and Implications for Thermal Treatment

Directory of Open Access Journals (Sweden)

Andrea Bloise

2018-03-01

Full Text Available Nowadays, due to the adverse health effects associated with exposure to asbestos, its inertization is one of the most important issues of waste risk management. Based on the research line of mechano-chemical and thermal treatment of asbestos containing materials, the aim of this study was to examine the effects of dry grinding on the structure, temperature stability and fibre size of chrysotile from Balangero (Italy, as well as standard UICC (Union for International Cancer Control amosite and standard UICC (Union for International Cancer Control crocidolite. Dry grinding was accomplished in an eccentric vibration mill by varying the grinding time (30 s, 5 and 10 min. Results show a decrease in crystallinity, the formation of lattice defects and size reduction with progressive formation of agglomerates in the samples after the mechanical treatment. Transmission electron microscopy (TEM results show that the final product obtained after 10 min of grinding is composed of non-crystalline particles and a minor residue of crystalline fibres that are not regulated because they do not meet the size criteria for a regulated fibre. Grinding results in a decrease of temperature and enthalpy of dehydroxylation (ΔHdehy of chrysotile, amosite and crocidolite. This permits us to completely destroy these fibres in thermal inertization processes using a lower net thermal energy than that used for the raw samples.

Spray drying of beryllium oxide powder

International Nuclear Information System (INIS)

Sepulveda, J.L.; Kahler, D.A.

1991-01-01

Forming of beryllia ceramics through dry pressing requires the agglomeration of the powder through spray drying. To produce high quality fired ceramics it is necessary to disperse/grind the primary powder prior to binder addition. Size reduction of the powder is accomplished using an aqueous system in Vibro-Energy mills (VEM) charged with beryllia media to minimize contamination. Two VEM mills of different size were used to characterize the grinding operation. Details of the grinding kinetics are described within the context of the Macroscopic Population Balance Model approach. Spray drying of the ceramic slurry was accomplished with both a centrifugal atomizer and a two fluid nozzle atomizer. Two different spray dryers were used. Important operating parameters affecting the size distribution of the spray dried powder are discussed

Effects of Sawdust and Rice husk Additives on Physical Properties of Ceramic Filter

OpenAIRE

Majid. Muhi Shukur; Mohsin Abbas Aswad; Saba Mohamed Bader

2017-01-01

Two processes were employed for forming, specifically,  slip casting and semi-dry press were used to manufacture ceramic filters from local raw materials, red clay and combustible materials  (sawdust and rice husk). Different proportions of additives were used as pores forming agents to create porosity in ceramic filter. Dried filters  were fired at temperature to 1000°C.   It was found that the forming technique and additives have great effect on the physical properties of the produced ...

Grinding behavior and surface appearance of (TiCp + TiBw/Ti-6Al-4V titanium matrix composites

Directory of Open Access Journals (Sweden)

Ding Wenfeng

2014-10-01

Full Text Available (TiCp + TiBw/Ti-6Al-4V titanium matrix composites (PTMCs have broad application prospects in the aviation and nuclear field. However, it is a typical difficult-to-cut material due to high hardness of the reinforcements, high strength and low thermal conductivity of Ti-6Al-4V alloy matrix. Grinding experiments with vitrified CBN wheels were conducted to analyze comparatively the grinding performance of PTMCs and Ti-6Al-4V alloy. Grinding force and force ratios, specific grinding energy, grinding temperature, surface roughness, ground surface appearance were discussed. The results show that the normal grinding force and the force ratios of PTMCs are much larger than that of Ti-6Al-4V alloy. Low depth of cut and high workpiece speed are generally beneficial to achieve the precision ground surface for PTMCs. The hard reinforcements of PTMCs are mainly removed in the ductile mode during grinding. However, the removal phenomenon of the reinforcements due to brittle fracture still exists, which contributes to the lower specific grinding energy and grinding temperature of PTMCs than Ti-6Al-4V alloy.

Virtual sensors for on-line wheel wear and part roughness measurement in the grinding process.

Science.gov (United States)

Arriandiaga, Ander; Portillo, Eva; Sánchez, Jose A; Cabanes, Itziar; Pombo, Iñigo

2014-05-19

Grinding is an advanced machining process for the manufacturing of valuable complex and accurate parts for high added value sectors such as aerospace, wind generation, etc. Due to the extremely severe conditions inside grinding machines, critical process variables such as part surface finish or grinding wheel wear cannot be easily and cheaply measured on-line. In this paper a virtual sensor for on-line monitoring of those variables is presented. The sensor is based on the modelling ability of Artificial Neural Networks (ANNs) for stochastic and non-linear processes such as grinding; the selected architecture is the Layer-Recurrent neural network. The sensor makes use of the relation between the variables to be measured and power consumption in the wheel spindle, which can be easily measured. A sensor calibration methodology is presented, and the levels of error that can be expected are discussed. Validation of the new sensor is carried out by comparing the sensor's results with actual measurements carried out in an industrial grinding machine. Results show excellent estimation performance for both wheel wear and surface roughness. In the case of wheel wear, the absolute error is within the range of microns (average value 32 μm). In the case of surface finish, the absolute error is well below Ra 1 μm (average value 0.32 μm). The present approach can be easily generalized to other grinding operations.

SCC of 2304 Duplex Stainless Steel-Microstructure, Residual Stress and Surface Grinding Effects.

Science.gov (United States)

Zhou, Nian; Peng, Ru Lin; Schönning, Mikael; Pettersson, Rachel

2017-02-23

The influence of surface grinding and microstructure on chloride induced stress corrosion cracking (SCC) behavior of 2304 duplex stainless steel has been investigated. Grinding operations were performed both parallel and perpendicular to the rolling direction of the material. SCC tests were conducted in boiling magnesium chloride according to ASTM G36; specimens were exposed both without external loading and with varied levels of four-point bend loading. Residual stresses were measured on selected specimens before and after exposure using the X-ray diffraction technique. In addition, in-situ surface stress measurements subjected to four-point bend loading were performed to evaluate the deviation between the actual applied loading and the calculated values according to ASTM G39. Micro-cracks, initiated by grinding induced surface tensile residual stresses, were observed for all the ground specimens but not on the as-delivered surfaces. Loading transverse to the rolling direction of the material increased the susceptibility to chloride induced SCC. Grinding induced tensile residual stresses and micro-notches in the as-ground surface topography were also detrimental.

SCC of 2304 Duplex Stainless Steel—Microstructure, Residual Stress and Surface Grinding Effects

Directory of Open Access Journals (Sweden)

Nian Zhou

2017-02-01

Full Text Available The influence of surface grinding and microstructure on chloride induced stress corrosion cracking (SCC behavior of 2304 duplex stainless steel has been investigated. Grinding operations were performed both parallel and perpendicular to the rolling direction of the material. SCC tests were conducted in boiling magnesium chloride according to ASTM G36; specimens were exposed both without external loading and with varied levels of four-point bend loading. Residual stresses were measured on selected specimens before and after exposure using the X-ray diffraction technique. In addition, in-situ surface stress measurements subjected to four-point bend loading were performed to evaluate the deviation between the actual applied loading and the calculated values according to ASTM G39. Micro-cracks, initiated by grinding induced surface tensile residual stresses, were observed for all the ground specimens but not on the as-delivered surfaces. Loading transverse to the rolling direction of the material increased the susceptibility to chloride induced SCC. Grinding induced tensile residual stresses and micro-notches in the as-ground surface topography were also detrimental.

SCC of 2304 Duplex Stainless Steel—Microstructure, Residual Stress and Surface Grinding Effects

Science.gov (United States)

Zhou, Nian; Peng, Ru Lin; Schönning, Mikael; Pettersson, Rachel

2017-01-01

The influence of surface grinding and microstructure on chloride induced stress corrosion cracking (SCC) behavior of 2304 duplex stainless steel has been investigated. Grinding operations were performed both parallel and perpendicular to the rolling direction of the material. SCC tests were conducted in boiling magnesium chloride according to ASTM G36; specimens were exposed both without external loading and with varied levels of four-point bend loading. Residual stresses were measured on selected specimens before and after exposure using the X-ray diffraction technique. In addition, in-situ surface stress measurements subjected to four-point bend loading were performed to evaluate the deviation between the actual applied loading and the calculated values according to ASTM G39. Micro-cracks, initiated by grinding induced surface tensile residual stresses, were observed for all the ground specimens but not on the as-delivered surfaces. Loading transverse to the rolling direction of the material increased the susceptibility to chloride induced SCC. Grinding induced tensile residual stresses and micro-notches in the as-ground surface topography were also detrimental. PMID:28772582

Effect of grinding conditions on the fatigue life of titanium 5Al-2.5Sn alloy

Science.gov (United States)

Rangaswamy, P.; Terutung, H.; Jeelani, S.

1991-01-01

An investigation into the effect of grinding conditions on the fatigue life of titanium 5Al-2.5Sn is presented. Damage to surface integrity and changes in the residual stresses distribution are studied to assess changes in fatigue life. A surface grinding machine, operating at speeds ranging from 2000 to 6000 fpm and using SiC wheels of grit sizes 60 and 120, was used to grind flat subsize specimens of 0.1-in. thickness. After grinding, the specimens were fatigued at a chosen stress and compared with the unadulterated material. A standard profilometer, a microhardness tester, and a scanning electron microscope were utilized to examine surface characteristics and measure roughness and hardness. Increased grinding speed in both wet and dry applications tended to decrease the fatigue life of the specimens. Fatigue life increased markedly at 2000 fpm under wet conditions, but then decreased at higher speeds. Grit size had no effect on the fatigue life.

short communication simple grinding-induced reactions of 2

African Journals Online (AJOL)

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SIMPLE GRINDING-INDUCED REACTIONS OF 2-AMINOBENZYL ... As part of our broad interest in the chemistry of heterocyclic compounds [10, 11], the .... study grant) and the University of Botswana (THT study grant) for financial support, Dr.

Effect of electroerosion grinding parameters on surface quality of cylindrical pieces out of tungsten monocrystals

International Nuclear Information System (INIS)

Zolotykh, B.N.; Marchuk, A.I.; Nikiforov, S.V.; Serdobov, B.F.; Yakunkin, M.M.

1978-01-01

Experimental data are presented on the examination of the electroerosion grinding of cylindrical parts made up of tungsten single crystals. Special attention has been paid to a comparative analysis of the influence of the electroerosion cutting out and grinding on the quality characteristics of a surface. The surface quality was assessed according to a widening of the X-ray emission line (110) by means of round diffraction patterns and by the metallographic method. It is shown that the microdistortions after the electroerosion grinding are considerably greater than those resulting from the electroerosion cutting out; however, after the electroerosion grinding the number of microcracks is considerably smaller. The experimental results obtained underwent a theoretical analysis within the framework of the Mitchell-Rockswell-Hirsch dislocation theory of failure of space-centered single crystals

Effect of Abrasion-Induced Contact Damage on the Optical Properties and Strength of Float Glass

Science.gov (United States)

2018-06-07

in glass. J Am Ceram Soc. 1969;52(6):338–339. 2. Mecholsky JJ Jr, Freiman SW, Rice RW. Effect of grinding on flaw geometry and fracture of glass. J...Am Ceram Soc. 1977;60(3–4):114–117. 3. Rice RW, Mecholsky JJ Jr. The nature of strength controlling machining flaws in ceramics. In: Hockey BJ, Rice...National Bureau of Standards; 1979. p. 351–378. 4. Rice RW, Mecholsky JJ Jr, Becher PF. The effect of grinding direction on flaw character and

Chemical and ceramic methods for the safe storage of actinides using monazite. 1997 annual progress report

International Nuclear Information System (INIS)

Boatner, L.A.

1997-01-01

'Oak Ridge National Laboratory (ORNL) and the Rockwell Science Center of Thousand Oaks, California, are carrying out a joint investigation of the chemical, physical, thermal, and radiation-resistance properties of the lanthanide orthophosphates (monazites) in both ceramic and single-crystal form with the objective of developing the scientific and technical base required for the application of these materials to the storage or disposal of actinide elements, including plutonium. An additional major objective of the research effort is to investigate the technical and scientific problems associated with the formation of both phase-pure monazite ceramics and multiphase monazite-ceramic composites for waste disposal or waste storage applications. These latter investigations encompass the development of low-temperature chemical synthesis routes for the formation of monoclinic monazite phases and the study of the densification properties of lanthanide orthophosphate powders to produce stable, high-density ceramics. Research Statement This research effort addresses several basic issues associated with the characteristics of lanthanide orthophosphates that make this class of materials extremely attractive candidates for application to the storage of actinide elements in general and plutonium in particular. Additionally, these materials are potentially important refractory ceramics in their own right, and many of the scientific issues addressed in this project are applicable to the development of what will constitute a new, highly stable family of ceramics for applications in a number of energy-related areas.'

Dead time and recovery time investigations on grinding plants with the aid of radioisotopes

Energy Technology Data Exchange (ETDEWEB)

Roetzer, H; Hagspiel, W

1977-02-01

With the aid of the radionuclides Mn 56 and Na 24 as tracers, respectively, the following characteristics were investigated for a roller mill and for a tandem air-swept grinding plant: the time of passage of the mill feed material, the retention time distribution in the grinding system (most frequent and mean retention time), and the time required for, respectively, 50%, 90% and 95% of the material to pass, in some instances separately for the three raw material components limestone, clay and sand. In addition, in the case of the air-swept grinding plant the time required for conveying the raw meal sample from the sampling point to the X-ray fluorescence analysis apparatus was determined. The mean retention time of the material in the two roller mills IV and V was 2.93 and 2.55 minutes respectively; for the tandem air-swept grinding plant it was 8 minutes. The time taken for 90% of the mill feed to pass through the mill was 5.5 and 5 minutes for the roller mills respectively and was about 18.3 minutes for the air-swept plant. The dead time vor conveying the raw meal sample to the X-ray fluorescence apparatus, including further grinding of the sample in a vibratory mill, was 12 minutes.

DSC, X-ray and FTIR studies of a gemfibrozil/dimethyl-β-cyclodextrin inclusion complex produced by co-grinding.

Science.gov (United States)

Aigner, Z; Berkesi, O; Farkas, G; Szabó-Révész, P

2012-01-05

The steps of formation of an inclusion complex produced by the co-grinding of gemfibrozil and dimethyl-β-cyclodextrin were investigated by differential scanning calorimetry (DSC), X-ray powder diffractometry (XRPD) and Fourier transform infrared (FTIR) spectroscopy with curve-fitting analysis. The endothermic peak at 59.25°C reflecting the melting of gemfibrozil progressively disappeared from the DSC curves of the products on increase of the duration of co-grinding. The crystallinity of the samples too gradually decreased, and after 35min of co-grinding the product was totally amorphous. Up to this co-grinding time, XRPD and FTIR investigations indicated a linear correlation between the cyclodextrin complexation and the co-grinding time. After co-grinding for 30min, the ratio of complex formation did not increase. These studies demonstrated that co-grinding is a suitable method for the complexation of gemfibrozil with dimethyl-β-cyclodextrin. XRPD analysis revealed the amorphous state of the gemfibrozil-dimethyl-β-cyclodextrin product. FTIR spectroscopy with curve-fitting analysis may be useful as a semiquantitative analytical method for discriminating the molecular and amorphous states of gemfibrozil. Copyright © 2011 Elsevier B.V. All rights reserved.

Effect of electromagnetic radiation on the kinetics of grinding a mineral

International Nuclear Information System (INIS)

Lopez M, A.; Delgadillo G, J. A.; Vega C, H. R.

2015-10-01

In this study the effect of kinetic grinding of a mineral was investigated when is pre treated with ionizing electromagnetic radiation. This radiation is with 15 MeV photons produced by a Linac for Radiotherapy. The results for the irradiated sample with respect to the non-irradiated indicate that there were changes in the structure of the minerals in the sample under study. Changes were observed through scanning electron microscopy and X-ray diffraction, combined with the refinement of the diffraction profiles by the Rietveld method using the software Maud Program. The grinding kinetics shows a constant distribution of slightly greater size through time used for the irradiated sample. A reduction of 11.2% of the Bond (Wi) work index was reached, going from 10.91 to 9.69 kw h/t for the irradiated sample. This parameter represents the fracture toughness of a mineral. The results indicate greater efficiency of energy applied to the grinding of the irradiated sample with respect to the non-irradiated. (Author)

The grinding of uranium dioxide from fluidized beds; Estudio del m icronizado del UO{sub 2} procedente de lechos Fluidizados

Energy Technology Data Exchange (ETDEWEB)

Alonso Folgueras, J A

1974-07-01

This work deals with the UO{sub 2} vibratory grinding, the UO{sub 2} obtained from fluidized beds. In this study the grinding time has been correlated with surface area, stoichiometry, granulometry and grinded product contamination. The efficiency losses in the grinding of moisten UO{sub 2} are outlined. Finally it is made a brief study of the granulate obtained from the grinded UO{sub 2} as well as the green pellets resulting from it, taking into consideration the dispersion of its density and height. (Author)

Variability of residual stresses and superposition effect in multipass grinding of high-carbon high-chromium steel

Science.gov (United States)

Karabelchtchikova, Olga; Rivero, Iris V.

2005-02-01

The distribution of residual stresses (RS) and surface integrity generated in heat treatment and subsequent multipass grinding was investigated in this experimental study to examine the source of variability and the nature of the interactions of the experimental factors. A nested experimental design was implemented to (a) compare the sources of the RS variability, (b) to examine RS distribution and tensile peak location due to experimental factors, and (c) to analyze the superposition relationship in the RS distribution due to multipass grinding technique. To characterize the material responses, several techniques were used, including microstructural analysis, hardness-toughness and roughness examinations, and retained austenite and RS measurements using x-ray diffraction. The causality of the RS was explained through the strong correlation of the surface integrity characteristics and RS patterns. The main sources of variation were the depth of the RS distribution and the multipass grinding technique. The grinding effect on the RS was statistically significant; however, it was mostly predetermined by the preexisting RS induced in heat treatment. Regardless of the preceding treatments, the effect of the multipass grinding technique exhibited similar RS patterns, which suggests the existence of the superposition relationship and orthogonal memory between the passes of the grinding operation.

The effects of pf grind quality on coal burnout in a 1 MW combustion test facility

Energy Technology Data Exchange (ETDEWEB)

Richelieu Barranco; Michael Colechin; Michael Cloke; Will Gibb; Edward Lester [University of Nottingham, Nottingham (United Kingdom). School of Chemical, Environmental and Mining Engineering, Nottingham Fuel and Energy Centre

2006-05-15

A study was carried out to determine the effect of pf particle size distribution on coal burnout propensity in a 1 MW pulverised fuel burner. The specific aim of the work was to assess the improvement in combustion performance achievable by retrofitting commercially available high performance static or dynamic classifiers to existing plants. Two coals were used and were selected as representative of extremes in fuel characteristics experienced by coal importing utilities in Europe. Each coal was fired in the unit at a range of grind sizes to determine the overall impact of a variable performance from a mill. The levels of unburnt carbon in the resultant flyashes for the two coals showed significantly different behaviour. For the higher volatile coal, the unburnt carbon was found to be insensitive to grind quality. However, the coarser grinds of the other coal produced significantly lower unburnt carbon than expected when compared with the finest grinds. Generally the results indicate that the installation of improved classification technology, leading to a finer product, will help to lower unburnt carbon levels. Nevertheless, further work will be necessary to establish the levels of diminishing returns for grind size, burnout performance and grind costs. 21 refs., 4 figs., 4 tabs.

Comparison of tungsten carbide and stainless steel ball bearings for grinding single maize kernels in a reciprocating grinder

Science.gov (United States)

Reciprocating grinders can grind single maize kernels by shaking the kernel in a vial with a ball bearing. This process results in a grind quality that is not satisfactory for many experiments. Tungesten carbide ball bearings are nearly twice as dense as steel, so we compared their grinding performa...

Effect of cutting edge radius on surface roughness in diamond tool turning of transparent MgAl2O4 spinel ceramic

Science.gov (United States)

Yue, Xiaobin; Xu, Min; Du, Wenhao; Chu, Chong

2017-09-01

Transparent magnesium aluminate spinel (MgAl2O4) ceramic is one of an important optical materials. However, due to its pronounced hardness and brittleness, the optical machining of this material is very difficult. Diamond turning has advantages over the grinding process in flexibility and material removal rate. However, there is a lack of research that could support the use of diamond turning technology in the machining of MgAl2O4 spinel ceramic. Using brittle-ductile transition theory of brittle material machining, this work provides critical information that may help to realize ductile-regime turning of MgAl2O4 spinel ceramic. A characterization method of determination the cutting edge radius is introduced here. Suitable diamond tools were measured for sharpness and then chosen from a large number of candidate tools. The influence of rounded cutting edges on surface roughness of the MgAl2O4 spinel ceramic is also investigated. These results indicate that surface quality of MgAl2O4 spinel is relate to the radius of diamond tool's cutting edge, cutting speed, and feed rate. Sharp diamond tools (small radius of cutting edge) facilitated ductile-regime turning of MgAl2O4 spinel and shows great potential to reduce surface roughness and produce smoother final surface.

Crack propagation and the material removal mechanism of glass-ceramics by the scratch test.

Science.gov (United States)

Qiu, Zhongjun; Liu, Congcong; Wang, Haorong; Yang, Xue; Fang, Fengzhou; Tang, Junjie

2016-12-01

To eliminate the negative effects of surface flaws and subsurface damage of glass-ceramics on clinical effectiveness, crack propagation and the material removal mechanism of glass-ceramics were studied by single and double scratch experiments conducted using an ultra-precision machine. A self-manufactured pyramid shaped single-grit tool with a small tip radius was used as the scratch tool. The surface and subsurface crack propagations and interactions, surface morphology and material removal mechanism were investigated. The experimental results showed that the propagation of lateral cracks to the surface and the interaction between the lateral cracks and radial cracks are the two main types of material peeling, and the increase of the scratch depth increases the propagation angle of the radial cracks and the interaction between the cracks. In the case of a double scratch, the propagation of lateral cracks and radial cracks between paired scratches results in material peeling. The interaction between adjacent scratches depends on the scratch depth and separation distance. There is a critical separation distance where the normalized material removal volume reaches its peak. These findings can help reduce surface flaws and subsurface damage induced by the grinding process and improve the clinical effectiveness of glass-ceramics used as biological substitute and repair materials. Copyright © 2016 Elsevier Ltd. All rights reserved.

The First Static and Dynamic Analysis of 3-D Printed Sintered Ceramics for Body Armor Applications

Science.gov (United States)

2016-09-01

hardness , and fracture strength) and semi-infinite penetration performance of 3-D printed sintered alumina. These results are compared with traditionally...parameters (including density, hardness , and fracture strength), semi-infinite penetration performance, and the fracture profile following impact of 3...of advanced ceramics differs mostly in terms of the initial green part formation when compared with a traditional manufacturing process. The

Optimization of Process Variables for Grinding of Ibuprofen using Response Surface Methodology

Energy Technology Data Exchange (ETDEWEB)

Sim, Chol-Ho [Sangji University, Wonju (Korea, Republic of)

2013-12-15

Ibuprofen, non-steroidal anti-inflammatory drugs; NSAIDs, is a highly crystalline substance with the pharmaceutical properties of poor solubility and low bioavailability. The size reduction of ibuprofen is needed to improve the solubility. The objective of this study is to optimize the grinding condition of ibuprofen. Grinding of ibuprofen was carried out using a planetary mill. Grinding parameters were optimized using Box-Behnken experimental design method. The physical characteristics of ground ibuprofen were investigated for the particle size by particle size analyzer, for the crystal size by X-ray diffraction (XRD), and for the tensile strength by tensile/compression tester. The optimum conditions for the milling of ibuprofen were 290 rpm of the revolution number of mill, 24.6 g of the weight of sample, and 10minutes of grinding time. The measured value of the particle size of ground ibuprofen at these optimum conditions was 13.5 µm. The results showed that the crystal size of ibuprofen was reduced by the planetary milling process. In case the relative density of the tablets formulated of ground ibuprofen was range of 0.85-0.90, the tensile strength of them was range of 12-14 Kg{sub f}/cm{sup 2}.

Performance Evaluation of Abrasive Grinding Wheel Formulated ...

African Journals Online (AJOL)

This paper presents a study on the formulation and manufacture of abrasive grinding wheel using locally formulated silicon carbide abrasive grains. Six local raw material substitutes were identified through pilot study and with the initial mix of the identified materials, a systematic search for an optimal formulation of silicon ...

Metals and Ceramics Division annual progress report, October 1, 1978-June 30, 1979

International Nuclear Information System (INIS)

Peterson, S.

1979-09-01

Research is reported concerning: (1) engineering materials including materials compatibility, mechanical properties, nondestructive testing, pressure vessel technology, and welding and brazing; (2) fuels and processes consisting of ceramic technology, fuel cycle technology, fuels evaluation, fuels fabrication and metals processing; and (3) materials science which includes, ceramic studies, physical metallurgy and properties, radiation effects and microstructural analysis, metastable and superconducting materials, structure and properties of surfaces, theoretical research, and x-ray research and applications. Highlights of the work of the metallographic group and the current status of the High-Temperature Materials Laboratory (HTML) and the Materials and Structures Technology Management Center (MSTMC) are presented

Semi-annual sampling of Fourmile Branch and its seeplines in the F and H Areas of SRS: July 1992

International Nuclear Information System (INIS)

Dixon, K.L.; Rogers, V.A.

1994-04-01

In July 1992, water samples were collected from Fourmile Branch (FMB) and its seeplines in the vicinity of the F and H-Area seepage basins. The samples were collected from five seepline locations in F Area, five seepline locations in H Area, and three stream locations on FMB. The sampling event was the first in a series of three semi-annual sampling event was the first in a series of three semi-annual sampling events aimed at characterizing the shallow groundwater outcropping into FMB and its wetlands. In the past, this groundwater has been shown to contain contaminants migrating from the F- and H-Area seepage basins. The samples were analyzed for Appendix 9 metals, various radionuclides, selected volatile compounds, and selected inorganic constituents and parameters. Results from the July 1992 sampling event suggest that the seeplines in both F and H Areas and FMB continue to be influenced by contaminants migrating from the F- and H-Area seepage basins. However, when compared to 1989 measurements, the concentrations of most of the constituents have declined. Contaminant concentration measured in July 1992 were compared to primary drinking water standards (PDWS), secondary drinking water standards (SDWS), and maximum contaminant levels (MCL) enforceable in 1993. Results were also compared to 1989 measurements at corresponding sampling locations and to background samples collected as part of the July 1992 sampling event. Using two different statistical tests, concentrations of selected F- and H-Area seepline analytes were compared to background samples. These tests were designed to detect if concentrations of contaminants along the F- and H-Area seeplines were greater than background concentrations

Online monitoring of a belt grinding process by using a light scattering method

International Nuclear Information System (INIS)

Boehm, Johannes; Vernes, Andras; Vorlaufer, Georg; Vellekoop, Michael

2010-01-01

Industrially ground surfaces often have a characteristic surface topography known as chatter marks. The surface finishing is mainly monitored by optical measurement techniques. In this work, the monitoring of an industrial belt grinding process with a light scattering sensor is presented. Although this technique is primarily applied for parametric surface roughness analysis, here it is shown that it enables also the measurement of the surface topography, i.e., the chatter marks occurring during the belt grinding process. In particular, it is proven that the light scattering method is appropriate to measure online the topography of chatter marks. Furthermore, the frequency analysis of the data reveals that the wavelength of chatter marks strongly depends on process parameters, such as the grinding speed.

The Effect of the Wear of Rotor Pins on Grinding Efficiency in a High-speed Disintegrator

Directory of Open Access Journals (Sweden)

Karel DVOŘÁK

2018-02-01

Full Text Available One of the directions intensively investigated in the field of milling is high-energy milling (HEM. One type of HEM is high-speed grinding in high-speed disintegrators. This type of mill is particularly suitable for the grinding and activation of fine powder materials. It has several advantages, such as a very intensive and continual refining process. One disadvantage is that its grinding pins are prone to abrasion, which may result in a decrease of the efficiency of grinding. This effect was investigated in this paper. Laboratory high speed disintegrator DESI 11 with steel pins was used. Portland clinker was chosen for the experiment, because of its average hardness. After each kilogram of the milled material, a sample was taken and the weight loss of the rotors was measured. The wear of the rotors was also measured using the 3D optical scanner ATOS Triple Scan. Results show that wear of rotors has a significant impact on the grinding efficiency.DOI: http://dx.doi.org/10.5755/j01.ms.24.1.17737

The Effect of Wood Alignment on Wood Grinding – Part 2: Fines Character and Microscopic Observations

Directory of Open Access Journals (Sweden)

Sabine Heinemann

2016-01-01

Full Text Available During industrial wood grinding, logs are pressed against a rotating stone, with the logs and fibre axes parallel to the axis of the stone. For this study, wood blocks were fed into a laboratory grinder with various alignments in relation to the surface of the grinding stone. The effects of the alignment on the properties of the pulp, the amount, and the quality of the fines were measured, and a grinding mechanism is proposed. In this paper, the obtained results showed that the pulp quality was highly sensitive to the angle between the stone surface and the log, and different for fatigue-based and force-based grinding. The tests were observed using microscopic techniques and discussed in terms of fines amount and fines quality. In gentle refining, the fibre structure is loosened by fatigue before it is bent on the surface, pressure pulses produce fibrillar material, and fibres develop good bonding ability. In forced grinding, the process is “violent” and the fibre wears and is crushed immediately on the surface into small particles with low bonding ability.

Hydrogen effects in anodic grinding of WC-Co sintered alloy

International Nuclear Information System (INIS)

Lunarska, E.; Zaborski, St.

2001-01-01

The effects of anodic polarization applied in grinding of sintered WC C o alloy on properties of surface layer, quality of ground surface and efficiency of the treatment were studied. The nonmonotonical change of the surface roughness, the energy consumption and the wear of tool was stated at increasing anodic polarization. The optimum values of above parameters were achieved at application of anodic polarization at which the Co selective dissolution and hydrogen ingress into the ground metal. affecting the internal friction spectra were stated. The assistance of hydrogen induced deterioration and Co selective dissolution in the surface layer in the anodic grinding of WC-Co alloy has been discussed. (author)

Westinghouse Modular Grinding Process - Enhancement of Volume Reduction for Hot Resin Supercompaction - 13491

Energy Technology Data Exchange (ETDEWEB)

Fehrmann, Henning [Westinghouse Electric Germany GmbH, Dudenstr. 44, D-68167 Mannheim (Germany); Aign, Joerg [Westinghouse Electric Germany GmbH, Global D and D and Waste Management, Tarpenring 6, D-22419 Hamburg (Germany)

2013-07-01

In nuclear power plants (NPP) ion exchange (IX) resins are used in several systems for water treatment. Spent resins can contain a significant amount of contaminates which makes treatment for disposal of spent resins mandatory. Several treatment processes are available such as direct immobilization with technologies like cementation, bitumisation, polymer solidification or usage of a high integrity container (HIC). These technologies usually come with a significant increase in final waste volume. The Hot Resin Supercompaction (HRSC) is a thermal treatment process which reduces the resin waste volume significantly. For a mixture of powdered and bead resins the HRSC process has demonstrated a volume reduction of up to 75 % [1]. For bead resins only the HRSC process is challenging because the bead resins compaction properties are unfavorable. The bead resin material does not form a solid block after compaction and shows a high spring back effect. The volume reduction of bead resins is not as good as for the mixture described in [1]. The compaction properties of bead resin waste can be significantly improved by grinding the beads to powder. The grinding also eliminates the need for a powder additive.Westinghouse has developed a modular grinding process to grind the bead resin to powder. The developed process requires no circulation of resins and enables a selective adjustment of particle size and distribution to achieve optimal results in the HRSC or in any other following process. A special grinding tool setup is use to minimize maintenance and radiation exposure to personnel. (authors)

Effect of ultrasound on dynamics characteristic of the cavitation bubble in grinding fluids during honing process.

Science.gov (United States)

Guo, Ce; Zhu, Xijing

2018-03-01

The effect of ultrasound on generating and controlling the cavitation bubble of the grinding fluid during ultrasonic vibration honing was investigated. The grinding fluid on the surface of the honing stone was measured by utilizing the digital microscope VHX-600ESO. Based on analyzing the cavitation mechanism of the grinding fluid, the bubble dynamics model under conventional honing (CH) and ultrasonic vibration honing (UVH) was established respectively. Difference of dynamic behaviors of the bubble between the cases in UVH and CH was compared respectively, and the effects of acoustic amplitude and ultrasonic frequency on the bubble dynamics were simulated numerically using the Runge-Kutta fourth order method with variable step size adaptive control. Finally, the cavitation intensity of grinding fluids under ultrasound was measured quantitatively using acoustimeter. The results showed that the grinding fluid subjected to ultrasound can generate many bubbles and further forms numerous groups of araneose cavitation bubbles on the surface of the honing stone. The oscillation of the bubble under UVH is more intense than the case under CH, and the maximum velocity of the bubble wall under UVH is higher two magnitudes than the case under CH. For lower acoustic amplitude, the dynamic behaviors of the bubble under UVH are similar to that case under CH. As increasing acoustic amplitude, the cavitation intensity of the bubble is growing increased. Honing pressure has an inhabitation effect on cavitation effect of the grinding fluid. The perfect performance of cavitation of the grinding fluid can be obtained when the device of UVH is in the resonance. However, the cavitation intensity of the grinding fluid can be growing weakened with increasing ultrasonic frequency, when the device of UVH is in the off-resonance. The experimental results agree with the theoretical and numerical analysis, which provides a method for exploring applications of the cavitation effect in

Hybrid Multiple Soft-Sensor Models of Grinding Granularity Based on Cuckoo Searching Algorithm and Hysteresis Switching Strategy

Directory of Open Access Journals (Sweden)

Jie-Sheng Wang

2015-01-01

Full Text Available According to the characteristics of grinding process and accuracy requirements of technical indicators, a hybrid multiple soft-sensor modeling method of grinding granularity is proposed based on cuckoo searching (CS algorithm and hysteresis switching (HS strategy. Firstly, a mechanism soft-sensor model of grinding granularity is deduced based on the technique characteristics and a lot of experimental data of grinding process. Meanwhile, the BP neural network soft-sensor model and wavelet neural network (WNN soft-sensor model are set up. Then, the hybrid multiple soft-sensor model based on the hysteresis switching strategy is realized. That is to say, the optimum model is selected as the current predictive model according to the switching performance index at each sampling instant. Finally the cuckoo searching algorithm is adopted to optimize the performance parameters of hysteresis switching strategy. Simulation results show that the proposed model has better generalization results and prediction precision, which can satisfy the real-time control requirements of grinding classification process.

Analysis of the influence of process conditions on the surface finish of ceramic materials manufactured by EDM; Analisis de la influencia de las condiciones de proceso sobre el acabado superficial de materiales ceramicos fabricados por electroerosion

Energy Technology Data Exchange (ETDEWEB)

Puertas-Arbizu, I.; Luis-Perez, C. J.

2004-07-01

Electrical discharge machining (EDM) is an emerging alternative versus some other manufacturing processes of conductive ceramic materials, such as: laser machining, electrochemical machining, abrasive water jet, ultrasonic machining and diamond wheel grinding. Due to its interest in the industrial field, in this work a study of the influence of process conditions on the surface aspect of three conductive ceramic materials: hot-pressed boron carbide (B{sub 4}C), reaction-bonded silicon carbide (SiSiC) and cobalt-bonded tungsten carbide (WC-Co) is carried out. These materials are to be electrical discharge machined under different machining conditions and in the particular case of finish stages (Ra{<=} 1 {mu}m). (Author)

Carving up Word Meaning: Portioning and Grinding

Science.gov (United States)

Frisson, S.; Frazier, L.

2005-01-01

Two eye-tracking experiments investigated the processing of mass nouns used as count nouns and count nouns used as mass nouns. Following Copestake and Briscoe (1995), the basic or underived sense of a word was treated as the input to a derivational rule (''grinding'' or ''portioning'') which produced the derived sense as output. It was…

Achievement report for fiscal 1989. Research and development of ceramic gas turbine (Development of test and evaluation methods for ceramic member bonding technology); 1989 nendo ceramic gas turbine no kenkyu kaihatsu seika hokokusho. Ceramic buzai setsugo gijutsu no shiken hyoka hoho no kaihatsu

Energy Technology Data Exchange (ETDEWEB)

NONE

1990-05-01

Development of test and evaluation methods has been performed on a technology to bond ceramics with metals as a support to develop a ceramic gas turbine (CGT), from the viewpoint that what governs bonding is residual stress. Activities were made in the following three fields: 1) investigative studies, 2) tests and researches, and 3) analytical studies. In Item 1, literatures were investigated, and research plans were established with regard to residual stress. Selections were made on Si3N4 as the ceramics, ordinary steel (S45C) as the metal, butt joint bonding of flat plates with each other as the bonding method, X-ray stress measuring method and IF method (semi-destructive test) as the residual stress measuring methods, and the finite element method as the analytical method. In Item 2, bonded test pieces were made, and the residual stress measuring test was performed to discuss the test and evaluation methods in relation with the bonding patterns and adaptability of the bonding. In Item 3, basic discussions were given on applicability of the residual stress analysis method using the finite element method, and on analysis of the affecting factors and modeling. (NEDO)

Metals and Ceramics Division annual progress report, October 1, 1978-June 30, 1979

Energy Technology Data Exchange (ETDEWEB)

Peterson, S. (ed.)

1979-09-01

Research is reported concerning: (1) engineering materials including materials compatibility, mechanical properties, nondestructive testing, pressure vessel technology, and welding and brazing; (2) fuels and processes consisting of ceramic technology, fuel cycle technology, fuels evaluation, fuels fabrication and metals processing; and (3) materials science which includes, ceramic studies, physical metallurgy and properties, radiation effects and microstructural analysis, metastable and superconducting materials, structure and properties of surfaces, theoretical research, and x-ray research and applications. Highlights of the work of the metallographic group and the current status of the High-Temperature Materials Laboratory (HTML) and the Materials and Structures Technology Management Center (MSTMC) are presented. (FS)

Production of talc nano sheets via fine grinding and sonication processes

International Nuclear Information System (INIS)

Samayamutthirian Palaniandy; Noorina Hidayu Jamil Khairun Azizi Mohd Azizli; Syed Fuad Saiyid Hashim; Hashim Hussin

2009-01-01

Fine grinding of high purity talc in jet mill at low grinding pressure was carried out by varying the feed rate and classifier rotational speed. These ground particles were sonicated in laboratory ultrasonic bath by varying the soniction period at five levels. The ground and sonicated particles were characterized in terms of particle size and particle size distribution. Mechanochemical and sonochemical effect of talc was determine via X-ray diffraction. Particle shape and surface texture of the ground and sonicated product was determined via scanning electron microscope and transmission electron microscope. The ground particle size exhibited particle size below 10 μm with narrow size distribution. The reduction of peak intensity in (002) plane indicated the layered structure has been distorted. The sonicated talc shows that the thickness of the talc particles after the sonication process is 20 nm but the lateral particle size still remains in micron range. The reduction of the XRD peak intensity for (002) plane and thickness of sonicated talc as shown in SEM and TEM micrographs proves that fine grinding and sonication process produces talc nano sheets. (author)

Obtention and characterization of ceramic products with addition of the mineral coal bottom ashes from thermoelectric power plants

International Nuclear Information System (INIS)

Kniess, C.T.; Prates, P.B.; Brys, M.; Martins, G.J.; Riella, H.G.; Bernardin, A.

2011-01-01

The physical, chemical and mineralogical properties of mineral coal bottom ash derived from thermoelectric power plants are compatible with various raw materials used in ceramic industries, which indicates a possibility of partial or fully substitution of raw materials by this residue. This work intends to obtain and characterize ceramic products with additions of different percentages of bottom ash coal. For this, was used a commercial ceramic body (CI) made by an industry in the state of Santa Catarina. The formulations of the ceramics products were obtained by the mixture design (planning network Simplex). The byproduct of coal bottom ash was found to be an attractive raw material source of SiO_2 and Al_2O_3 to obtain ceramic materials. Was demonstrated the possibility of developing a ceramic materials classified as semi-porous (6 10) with additions of up to 20% of coal bottom ash in the composition of the ceramic body. (author)

Grinding Glass Disks On A Belt Sander

Science.gov (United States)

Lyons, James J., III

1995-01-01

Small machine attached to table-top belt sander makes possible to use belt sander to grind glass disk quickly to specified diameter within tolerance of about plus or minus 0.002 in. Intended to be used in place of production-shop glass grinder. Held on driveshaft by vacuum, glass disk rotated while periphery ground by continuous sanding belt.

Effectiveness of dust control methods for crystalline silica and respirable suspended particulate matter exposure during manual concrete surface grinding.

Science.gov (United States)

Akbar-Khanzadeh, Farhang; Milz, Sheryl A; Wagner, Cynthia D; Bisesi, Michael S; Ames, April L; Khuder, Sadik; Susi, Pam; Akbar-Khanzadeh, Mahboubeh

2010-12-01

Concrete grinding exposes workers to unacceptable levels of crystalline silica dust, known to cause diseases such as silicosis and possibly lung cancer. This study examined the influence of major factors of exposure and effectiveness of existing dust control methods by simulating field concrete grinding in an enclosed workplace laboratory. Air was monitored during 201 concrete grinding sessions while using a variety of grinders, accessories, and existing dust control methods, including general ventilation (GV), local exhaust ventilation (LEV), and wet grinding. Task-specific geometric mean (GM) of respirable crystalline silica dust concentrations (mg/m³ for LEV:HEPA-, LEV:Shop-vac-, wet-, and uncontrolled-grinding, while GV was off/on, were 0.17/0.09, 0.57/0.13, 1.11/0.44, and 23.1/6.80, respectively. Silica dust concentrations (mg/m³ using 100-125 mm (4-5 inch) and 180 mm (7 inch) grinding cups were 0.53/0.22 and 2.43/0.56, respectively. GM concentrations of silica dust were significantly lower for (1) GV on (66.0%) vs. off, and (2) LEV:HEPA- (99.0%), LEV:Shop-vac- (98.1%) or wet- (94.4%) vs. uncontrolled-grinding. Task-specific GM of respirable suspended particulate matter (RSP) concentrations (mg/m³ for LEV:HEPA-, LEV:Shop-vac-, wet-, and uncontrolled grinding, while GV was off/on, were 1.58/0.63, 7.20/1.15, 9.52/4.13, and 152/47.8, respectively. GM concentrations of RSP using 100-125 mm and 180 mm grinding cups were 4.78/1.62 and 22.2/5.06, respectively. GM concentrations of RSP were significantly lower for (1) GV on (70.2%) vs. off, and (2) LEV:HEPA- (98.9%), LEV:Shop-vac- (96.9%) or wet- (92.6%) vs. uncontrolled grinding. Silica dust and RSP were not significantly affected by (1) orientation of grinding surfaces (vertical vs. inclined); (2) water flow rates for wet grinding; (3) length of task-specific sampling time; or, (4) among cup sizes of 100, 115 or 125 mm. No combination of factors or control methods reduced an 8-hr exposure level to below the