APPENDIX B - PROCESSING OF INJECTION-MOLDING MATERIALS. 68 .... This is the final report of "Development of Processes and Techniques for ...... Silicone mold releases ... Usually occurs in the presence of an organic liquid or vapor ...

available developments in the resin transfer molding process is a registered .... molded by liquid injection. RTM include access doors for civil aircraft (Figure 2) and fuselage .... oxide fibers are under study such as silicon carbide, aluminum ...

Jan 1, 1983 ... Abstract: Pure silicon nitride shows a remarkable resistance to ... the composition, raw material impurities, and processing contaminants. ... Subject Terms: CERAMICS; DENSIFICATION; INJECTION MOLDING; LIQUID ...

Injection molding of polymers is currently utilized for numerous industrial applications. Because of high productivity and stable quality of molded products, the injection-molding process makes the production costs lower, and therefore, is expected to spread more widely in the future. This paper deals with a technique for improving the optical quality of injection molded polymer products using radiative heating. The birefringence frozen in a skin-layer of the molded part was reduced by CO{sub 2} laser heating, and the efficiency of this technique was investigated experimentally. Namely, a simple numerical calculation was performed to estimate the heating efficiency of CO{sub 2} laser in the polymer, effects of radiation heating on the skin-layer of the molded polymer were observed by using a mold with transparent windows, and the residual birefringence frozen in the final molded specimen was measured. The results clearly showed that the birefringence in the skin-layer of injection molded polymer strips was reduced with CO{sub 2} laser heating. The authors believe that the proposed method for reducing the birefringence frozen in injection-molded polymer products is suitable for practical molding, because process time required for the injection-molding is only slightly increased with this method.

The influence of process parameters on ?-injection molding (?IM) and on ?-injection molded parts has been investigated using Design of Experiments. A mold with a sensor applied at injection location was used to monitor actual injection pressure and to determine the cavity filling time. Flow markers position was measured on the polymer ?-parts to evaluate filling behavior of the polymer melt flowing through ?-features. Experimental results obtained under different processing conditions were evaluated to correlate the process parameter levels influence on the selected responses. Results showed that the injection speed in one of the most influencing process parameters on the ?IM process and on the ?-parts filling.

In manufacturing a DC motor body including a motor magnet by conventional processes, a magnet is fitted to the cylindrical molding core and a motor body is injection-molded within a cavity formed between a motor-body-forming mold and a cylindrical molding core to which the magnet is attached. Therefore, the magnet has to be molded and stocked before molding the motor body, thus being inapplicable to mass-production processes. To overcome these problems, the motor magnet and the motor body are molded in sequence in accordance with two separate molding steps by the use of the same molding core. This method can eliminate troublesome magnet fitting work and the need of magnet stock, and enhance the dimensional precision of motor magnet, thus being applicable to mass-production process while increasing the energy transduction efficiency of the DC motor.

This study investigates warpage of electronic dictionary battery covers fabricated using thin-wall injection molding as a replacement for conventional insert molding. The primary concern is the molding window in thin-wall injection molding for acrylonitrile?butadiene styrene (ABS) and polycarbonate (PC)+ABS plastics. Finally, the process parameters for thin-wall injection molding that eliminate warpage of electronic dictionary battery covers are identified. Experimental results demonstrate that the area of the molding window for ABS exceeds that for PC+ABS. Analysis of the molding window reveals that ABS is more appropriate than PC+ABS for battery covers. Low melt temperature, high injection speed, and high packing pressure eliminate battery cover warpage. Melt temperature is the most impo...

Fast replication of large-area femtosecond-laser-induced surface micro/nanostructures on plastic parts by injection molding is demonstrated. An STAVAX steel mold insert is irradiated by femtosecond laser pulses with linear or circular polarization to form periodic-like nanostructures or nanostructure-covered conical microstructures. It was then used for the process of thermal injection molding. The process provides high-volume manufacturing means to generate hydrophobic enhanced plastic parts, which is expected to be widely used in consumables and chemical/biomedical device industries.

Plastic injection molding has been widely used in the past and is a dominant forming approach today. As the customer demands require materials with better engineering properties that were not feasible with polymers, powder injection molding with metal and ceramic powders has received considerable attention in recent decades. To better understand the differences in the plastic injection molding, metal injection molding, and ceramic injection molding, the effects of the core process parameters on the process performances has been studied using the state-of-the-art computer-aided engineering (CAE) design tool, PIMSolver? The design of experiments has been conducted using the Taguchi method to obtain the relative contributions of various process parameters onto the successful operations.

Micro/nano replication processes, including micro/nano thermal forming (compression molding and hot embossing), UV-molding, micro injection molding, and glass micro molding are regarded as the most promising mass-production methods for micro/nano optical components because they offer high repeatability, mass producibility with low-cost and versatility in terms of molding material selection. To replicate micro/nano optical components, it is required to prepare the mold inserts that have the cavities of the same shape as the components. One can use any established methods to make mold, such as direct machining, wet etching, dry etching, electroforming, compaction and sintering, and so on. This paper reviews the general issues on mold fabrication and replication technologies for micro/nano optical components with our recent work and results in these areas.   

This study analyzed variations of mechanical characteristics that depend on the injection molding techniques during the blending of short glass fiber and polytetrafluoroethylene reinforced polycarbonate composites. A hybrid method including back-propagation neural network (BPNN), genetic algorithm (GA), and response surface methodology (RSM) are proposed to determine an optimal parameter setting of the injection molding process. The specimens are prepared under different injection molding processing conditions based on a Taguchi orthogonal array table. The results of 18 experimental runs were utilized to train the BPNN predicting ultimate strength, flexural strength, and impact resistance. Simultaneously, the RSM and GA approaches were individually applied to search for an optimal setting....

A newly developed ?-injection molding machine equipped with a screwless/two-plunger injection unit has been employed to mould miniaturized dog-bone shaped specimens on polyoxymethylene and its process capability and robustness have been analyzed. The influence of process parameters on ?-injection molding was investigated using the Design of Experiments technique. Injection pressure and piston stroke speed as well as part weight and dimensions were considered as quality factors over a wide range of process parameters. Experimental results obtained under different processing conditions were evaluated to correlate the process parameter levels influence on the selected responses, considering both average values and standard deviations.

In this paper, micro cutting tools were manufactured by the powder injection molding process. Most of cutting tools are manufactured by bulk-molding and grinding methods but, the fabrication of micro cutting tools is very difficult because of their minute flute shapes and cutting edges. Therefore, a powder injection molding (PIM) process was used to fabricate the green part of a micro cutting tool with zirconia mixer feedstock and the de-binding and sintering processes were performed. Besides, the grinding processes can be dropped by PIM. Finally, the micro cutting experiment using the newly manufactured tool by PIM was executed for verifying the utility of manufactured tool.

powders and green compacts before monolithic ceramics are densified .... porosity. These data are needed because of the interrelations among velocity, texture, ..... processing stages such as forming, injection molding, slip casting, infiltration, ...

Abstract. High toughness silicon nitride ceramics were processed with the addition of ... results will be discussed in terms of microstructural evolution during liquid ..... injections molding, cold compaction, etc:. can be easily modified to used ...

Advances in processing of LCPs could permit the incorporation of these polymers into other than .... Properties of injection molded LCP ASTM bars. 58. 3.4 ...... Third, LINbO3 is not readily integrated with silicon- or GaAs- based technology.

Molded Interconnect Devices (MIDs) are plastic substrates with electrical infrastructure. The fabrication of MIDs is usually based on injection molding and different process chains may be identified from this starting point. The use of MIDs has been driven primarily by the automotive sector, but rec...

make the process of developing required technologies more cost-effective. ..... The septum adapter is an injected molded device for holding the septum. ... The septum is molded from silicon rubber and provides an entry for the .... and/or liquid-based media may present a higher degree of complexity rendering such ...

In order to enhance the industries which supply assembly parts to Japan`s assembly industries in Thailand, research cooperation project on the plastic parts production technology has started. For the research cooperation, the mold design is effectively conducted using simulation technique of CAE (computer aided engineering), and an international easy injection molding control system is made using the molding support software for injection molding machines. In FY 1996, actual situations of plastic parts and assembly industries in Thailand have been investigated through the cooperation with the counterpart of Thailand. Demand and supply of engineering plastics, receive and inspection of parts, and current circumstances of molding processing makers in Thailand have been grasped. Based on the results of this investigation, proposal of basic plan, time schedule, and delivery plan of molding machines and testing equipment have been discussed, to make the basic plan. 18 refs., 4 figs., 23 tabs.

This bibliography contains citations concerning the recycling of scrap plastic produced in the injection-molding process. Plastic pellets made from scrap that are used in the injection-molding process are also discussed. Recycling equipment and automated recycling systems are described. Ways to utilize plastic scrap from used cars, packaging materials, and waste from polyurethane production are presented. (This updated bibliography contains 116 citations, 14 of which are new entries to the previous edition.)

This bibliography contains citations concerning the recycling of scrap plastic produced in the injection-molding process. Plastic pellets made from scrap that are used in the injection-molding process are also discussed. Recycling equipment and automated recycling systems are described. Ways to utilize plastic scrap from used cars, packaging materials, and waste from polyurethane production are presented. (This updated bibliography contains 102 citations, 13 of which are new entries to the previous edition.)

The bibliography contains citations concerning the recycling of scrap plastic produced in the injection molding process. Plastic pellets made from scrap, that are used in the injection molding process, are also discussed. Recycling equipment and automated recycling systems are described. The reuse of plastic scrap culled from junk automobiles and packaging materials is discussed, and waste byproducts from polyurethane production are described. (Contains a minimum of 80 citations and includes a subject term index and title list.)

The ground coils to be used along the entire length of a Magnetically Levitated transportation (MAGLEV) system need to withstand long-term outdoor service and be provided in extremely large quantities. It is for these reasons that we require them to be durable and inexpensive. Dicyclopentadiene, a major component of low viscous liquid in Reaction Injection Molding (RIM), is injected into the mold. It reacts with catalyst and cures in a short time to produce a substance featuring superior quality not obtainable by the conventional injection molding. Besides, the molding process may be undertaken at normal temperature and pressure, the molding equipment is inexpensive, and the insulation scheme of the wound coils can be simplified. Thus, there are several reasons that the ground coils are suitable for mass production. In this paper we discuss the application of RIM technology through our trial manufacture of practical ground coils incorporated with several improvements. We investigated the economic effect as well.   

Silicon nitride has been the favored material for manufacturing high-efficiency engine components for transportation due to its high temperature stability, good wear resistance, excellent corrosion resistance, thermal shock resistance, and low density. The use of silicon nitride in engine components greatly depends on the ability to fabricate near net-shape components economically. The absence of a material database for design and simulation has further restricted the engineering community in developing parts from silicon nitride. In this paper, the design and manufacturability of silicon nitride engine rotors for unmanned aerial vehicles by the injection molding process are discussed. The feedstock material property data obtained from experiments were used to simulate the flow of the material during injection molding. The areas susceptible to the formation of defects during the injection molding process of the engine component were identified from the simulations. A test sample was successfully injection molded using the feedstock and sintered to 99% density without formation of significant observable defects.

A foam material comprises a liquid polymer and a liquid isocyanate which is mixed to make a solution that is poured, injected or otherwise deposited into a corresponding mold. A reaction from the mixture of the liquid polymer and liquid isocyanate inside the mold forms a thermally collapsible foam structure having a shape that corresponds to the inside surface configuration of the mold and a skin that is continuous and unbroken. Once the reaction is complete, the foam pattern is removed from the mold and may be used as a pattern in any number of conventional casting processes.

Abstract A processing technology that facilitates quality injection molding without prior drying of polymer pellets has been proposed. The main idea is not to let the water evaporate to bubbles inside the mold. The polymer will be maintained hydrated as it was in the hopper of the injection molding machine throughout the entire molding processes by controlling the cavity pressure above the saturation pressure of water until solidified. In this work, the gas counter pressure (GCP) system has been designed and built to maintain the cavity pressure above the saturation pressure. The performance of the proposed method has been examined by checking the visual quality and the mechanical properties of the molded parts. The method has been tested with pellets of polymethyl methacrylate (PMMA), pol...

A problem with micromechanics is that the commonly used fabrication methods and materials are relatively expensive. To be competitive on the market, new low-cost materials and manufacturing methods are necessary. Different micro-devices have already been made, e.g., micropumps. Micro-replication also enables different materials like polymers, metals and ceramics to be used. The research was conducted through part design, mold fabrication, experimental analysis, and quality test. The process parameters including injection speed, melt temperature, mold temperature and packing pressure on quality of micropumps were investigated. The injection molded part was actuated by a piezoelectric disc. Flow test was conducted to check the micropump performance.

Manufacturing of new ceramic components may be improved significantly by the use of rapid prototyping processes especially in the development of miniaturized or micropatterned components. Most known generative ceramic molding processes do not provide a sufficient resolution for the fabrication of microstructured components. In contrast to this, a rapid prototyping process chain that for example, combines micro-stereolithography and low-pressure injection molding, allows the rapid manufacturing of ceramic microcomponents from functional models to preliminary or small-lot series. (orig.)

Discussions were given on quality improvement and cost reduction of heating and forming molds for household rubber, plastics and electronic device parts. This paper summarizes the achievements in fiscal 1998. Verification was made on chromium plated steel and stainless steel molds as to improvement in water repellency of the mold surface by injecting N and F ions, improvement in surface hardness by making the surface into CrN and CrF, and improvement in wear resistance. In order to inject the ions uniformly into the mold surface having irregularities, a high-frequency and high-energy power supply was developed. Development was made on a negative voltage induction pulse power supply taking synchronism with the above pulse power supply and a 50-kV field through device. The design and fabrication thereof have been completed and the trial operation has begun. In order to evaluate mold releasing performance and pollution effect on molds under the same conditions for all makes, a unified evaluation criterion was established. With regard to nitriding and chromation by means of nitrogen ion injection into chromium plated steels under the unified rubber composition, the mold releasing performance and pollution effect were evaluated in terms of economics. Residue of rubber material in a mold has decreased, and metal polluting effect has been improved. Quantitative evaluation was performed successfully by the CCD taken image processing of surface images. (NEDO)

In Liquid Composite Molding (LCM) processes, a fibrous reinforcement preform is placed or draped over a mold surface, the mold is closed and a resin is either injected under pressure or infused under vacuum to cover all the spaces in between the fibers of the preform to create a composite part. LCM is used in a variety of manufacturing applications, from the aerospace to the medical industries. In this manufacturing process, the properties of the fibrous reinforcement inside the closed mold is of great concern. Preform structure, volume fraction, and permeability all influence the processing characteristics and final part integrity. When preform fabrics are draped over a mold surface, the geometry and characteristics of both the bulk fabric and fiber tow bundles change as the fabric shears...

  Injection molding of magnesium alloy is a new process in which slurry is injected into a mold at semi-solid temperatures to form net-shape products from solid feed stock in one step. The mechanical properties of injection molded AZ91D are equivalent to or better than those of die casting. In this study, we investigated the relationship between the process parameter and mechanical properties of the AM-series magnesium alloy. The results obtained are summarized as follows : 1) A high barrel temperature reduces solid fraction and improves mechanical properties. But the properties tend to saturate above the melting point. 2) A high injection velocity results in a small grain size of residual liquid phase, producing better mechanical properties. 3) The tensile specimens of AM-series alloy show better mechanical properties than those of die castings   

An injection apparatus with a pressure vibration field was self-developed to study the effects of vibration frequency and vibration pressure on the mechanical properties and crystal structure of nylon6 during the process of vibration injection molding. Scanning electron microscope (SEM) and wide-angle X-ray diffraction (WAXD) measurements were conducted. Experimental results showed that the amount of spherulites in subsurface of vibration sample is much more than that of static sample, and the spherulites become more uniformly and perfect. In subsurface layer, vibration induced the change of crystal form from ?-form to ?-form. Tensile and impact strength of samples obtained via vibration injection molding were improved, while the elongation decreased.

Abstract Multifunctional mobile products, such as cellular phones, laptop computers, personal media players, etc., have become smaller and lighter; so the technology of thin-wall injection molding (TWIM) has been highlighted for making lightweight and compact mobile electronic products. Regarding mechanical properties, many portable electronic products should pass the so-called -drop test-; therefore, the evaluation of the dart (or impact) property of the housing that is made by the TWIM process is crucial for commercializing a product. However, extant research on the effect of injection molding process parameters on the physical properties of TWIM plates is insufficient as yet. Therefore, in this study, the pressure and temperature inside the cavity during the injection molding process ar...

The present invention relates to methods for embedded a micrometer and/or nanometer pattern into an injection molding tool. In a first main aspect, a micro/nanometer structured imprinting device is applied in, or on, an active surface so as to transfer the micro/nanometer patterned structure to the tool while the imprinting device is, at least partly, within a cavity of the injection molding tool. In a second main aspect, a base plate with a micro/nanometer structured pattern positioned on an upper part is positioned on the active surface within the tool, the lower part of the base plate facing the tool, the active surface receiving the base plate being non-planar on a macroscopic scale. Both aspects enable a simple and effective way of transferring the pattern, and the pattern may be transferred on the active working site of tool immediately prior to molding without the need for extensive preparations or remounting of the tool before performing the molding process.

Purpose - This purpose of this study is to investigate an effective method to manufacture propellers. Design/methodology/approach - The investment casting process and injection molding process have been applied separately to the rapid prototyping/rapid tooling (RP/RT) to obtain metal (Al-Si alloy) propellers and plastic (Acrylonitrile butadiene styrene - ABS) propellers. The two different manufacturing processes were compared following the same master model (MM). The Moldflow software is used to optimize the experimental parameters of the molding. Furthermore, a gypsum type of powder is used to produce the RP MM of the propeller according to the Pro-E software. The RP MM then is filled with a metallic resin material (at room temperature) to obtain a wax mold. Then, this wax mold was coatin...

Abstract in english Resin Transfer Molding (RTM) is a manufacturing process in which a liquid resin is injected into a closed mold pre-loaded with a porous fibrous preform, producing complex composite parts with good surface finishing. Resin flow is a critical step in the process. In this work, the numerical study of the resin flow in RTM applications was performed employing a general Computational Fluid Dynamics software which does not have a specific RTM module, making it necessary to use (more) the Volume of Fluid method for the filling problem solution. Examples were presented and compared with analytical, experimental and numerical results showing the validity and effectiveness of the present study, with maximum difference among these solutions of around 8%. Besides, based on the computational model for the RTM process, a new computational methodology was developed to simulate Light Resin Transfer Molding (LRTM). In this process, resin is injected into the mold through an empty injection channel (without porous medium) which runs all around the perimeter of the mold. The ability of FLUENT® package to simulate geometries which combine porous media regions with open (empty) regions was used. Two specific cases were simulated, showing the differences in time and behavior between RTM and LRTM processes.

Determination of the rheological behavior of a polymer melt under high shear rate is generally considered to be crucial for accurate simulation modeling of ultra high speed injection molding, a process that has been attracting more attention from researchers. In this study, a melt viscosity measurement system under high shear rate was established using an instrumented injection molding machine combined with a slit die. Polystyrene melt was studied. From measured pressure drop and volumetric flow rate, the slit flow model was used for the calculation of viscosity at wall shear strain rates up to 10^5 s^-^1. Good agreement in shear viscosity was found between results from conventional capillary rheometry and in-line measurement made using an injection molding machine for strain rates of 7 x ...

Semisolid injection molding is expected to be increasingly utilized as a forming process applicable to highly flammable magnesium alloys, since it can be carried out at temperatures lower than those of die casting. In this study, we investigated the effects of molding conditions on the tensile strength and internal casting defects of AZ91D magnesium alloy. Semisolid injection molding was conducted at injection speeds of 220, 300 and 400 mm·s?1 and fraction solids of 0.0, 0.3, 0.4 and 0.5. Whereas the volume fraction of casting defects decreased together with the decrease of injection speed, the mechanical strength reached a maximum at an injection speed of 300 mm·s?1. The investigation results show that in the solidification microstructure, ?-Mg and ?-Mg17Al12 phases, which were liquid during injection, were refined at higher injection speeds, suggesting that the tensile strength increases together with the injection speed if there are no casting defects. This trend might be due to the increased heat transfer coefficient between the mold and the slurry from the higher flow rate. On the other hand, the volume fraction of casting defects increased together with injection speed, and as a result the tensile strength deteriorated. When the injection speed was increased, the effects of decreased strength due to the increase in the volume fraction of casting defects counterbalanced the effects of increased strength due to the refinement of ?-Mg + ?-Mg17Al12 mixed phase. For this reason, the mechanical strength is considered to reach a maximum at an injection speed of 300 mm·s?1. Thus, we demonstrated that the tensile strength of semisolid products is affected not only by the volume fraction of casting defects, but also by the microstructure of the residual mixed phase precipitated, which is refined by increasing the injection speed.   

It is essential to study and optimize multiple objective functions such as binder system design, feedstock, part geometry, mold design, and processing conditions in order to develop a successful powder injection molding process. A powder with different combinations of binder systems and a binder system with different combinations of powder systems were investigated with a combined experimental and simulation study. First, an experimental rheological study was performed to evaluate the influence of the powder/binder combinations on the rheological behavior and thermal stability of carbonyl iron and stainless steel powder injection molding (PIM) feedstocks. Second, based on the characterization of the feedstock, the simulation study revealed that the pressure-related parameters such as wall ...

The purpose of this program was to design, select, and evaluate plastic materials for an injection molded, half-size steamtable tray to be used for the storage, reheat, and serving of processed food items at government facilities. In performance of this s...

condensate .... methanol, to enable processing. The monomers are essentially unreactive ..... are considered. The pressure is supplied by a compressed gas which exerts ...... normal resin transfer type mold, which need only have an injection ...... reservoir area of the bottom end cap and secure manifold cover with three cap ...

agency began the process of returning the. Shuttle to safe ..... a .02 to .04-inch- thick layer of silicon carbide in a chamber filled ..... provides a vent for the liquid Hydrogen tank portion of the .... Additionally, a new mold injection foam closeout ...

Melt flow during injection molding is non-Newtonian, non-isothermal, and unsteady. Software packages for the numerical simulation of such flows are prevalent in the plastics industry, but experimental data for benchmarking and verification of these programs are scarce. To address this situation, an optical access mold has been constructed with a rectangular mold cavity that can be illuminated from the top and bottom and viewed from the side. The mold has been placed in a Cincinnati Milacron VS-33 injection molding machine and has been used to study the flow of polyethylene melts. A digital CCD camera was used to record the progress of the melt as it filled the cavity from a gate near one of the cavity corners. The digital images were then processed to extract the melt front geometry as a function of time. Images of the flowing plastic, and polynomial fits to the melt front data for various sets of molding parameters are presented. In addition, the experimental data may be compared to the results of GOMA, a program developed at Sandia that can be used to simulate the flow of non-Newtonian fluids with free and fixed boundaries, if time allows.

Online process metrology is critical to ensuring manufacturing quality and productivity. This paper presents the design and modelling of a multivariate sensor that enables the simultaneous measurement of multiple parameters from within an RF shielded environment, e.g. an injection mold. A coded wave modulation scheme is developed for wirelessly transmitting the parameters through the mold. The design of the modulator is optimized through a coupled field analysis for noise reduction. The effectiveness of the sensing method is demonstrated in the online measurement of melt pressure, temperature, viscosity, and velocity. This sensing method is applicable to various process monitoring scenarios.

An aqueous injection molding process based on the gelling properties of certain naturally occurring polysaccharides, in particular agar, and its purified derivative, agavose, is described. The materials form nonviscous solutions at temperatures near 100{degrees}C which solidify to rigid gels upon cooling below the so-called gel point temperature, 37{degrees}C. Gels formed by these materials are strong, nominally 1500 g/cm{sup 2} for agar and 2500 g/cm{sup 2} for agavose at 3 wt% concentration. Molded parts can be dried and fired without use of absorbent powders or special debinding operations of any kind.

New approaches to the fabrication of microstructures of special shape were developed for polymers. Unusual superhydrophobic surface structures were achieved with the use of flexible polymers and hierarchical molds. Flexible polyurethane-acrylate coatings were patterned with microstructures with use of microstructured aluminum mold in a controlled UV-curing process. Electron microscope images of the UV-cured coatings on polymethylmethacrylate (PMMA) substrates revealed micropillars that were significantly higher than the corresponding depressions of the mold (even 47 vs. 35 ?m). The elongation was achieved by detaching the mold from the flexible, partially cured acrylate surface and then further curing the separated microstructure. The modified acrylate surface is superhydrophobic with a water contact angle of 156° and sliding angle of < 10°. Acrylic thermoplastic elastomers (TPE) were patterned with micro-nanostructured aluminum oxide molds through injection molding. The hierarchical surface of the elastomer showed elongated micropillars (57 ?m) with nail-head tops covered with nanograss. Comparison with a reference microstructure of the same material (35 ?m) indicated that the nanopores of the micro-nanomold assisted the formation of the nail-shaped micropillars. The elasticity of the TPE materials evidently plays a role in the elongation because similar elongation has not been found in hierarchically structured thermoplastic surfaces. The hierarchical micronail structure supports a high water contact angle (164°), representing an increase of 88° relative to the smooth TPE surface. The sliding angle was close to zero degrees, indicating the Cassie-Baxter state.

Abstract in portuguese A fabricação de moldes por técnicas de prototipagem rápida, como a estereolitografia (SL), é considerada uma importante tecnologia no auxílio ao desenvolvimento de produtos de plástico moldados por injeção. Embora esta tecnologia se mostre vantajosa, a vida útil dos moldes pode ser bastante reduzida em decorrência, por exemplo, de forte adesão entre o polímero injetado e o material do molde SL. Neste trabalho é investigado o uso da técnica de recobrimento m (more) etálico com Ni-P por deposição electroless sobre moldes de injeção, fabricados por SL com a resina DSM SOMOS 7110®. Foram comparados resultados de moldagem de PA6.6 em moldes fabricados com e sem recobrimento metálico evidenciando a possibilidade de utilizar a técnica de metalização como alternativa para a moldagem deste material em moldes SL, uma vez que a vida útil foi superior. Abstract in english Manufacturing of moulds by rapid prototyping processes, such as stereolithography (SL), is considered an important technology to aid the development of injection moulding plastic products. Although this technology shows significant advantages, the lifetime of moulds may be drastically be reduced due to strong adhesion between the injected polymer and the material of the SL mould. This work investigates the use of Ni-P metal coating obtained by electroless deposition on SL (more) moulds manufactured with the resin DSM SOMOS 7110. Specimens of PA6.6 have been injected into SL moulds manufactured with and without metal coating. The results showed that the electroless metal coating process can be an appropriate alternative to allow moulding of small series of PA6.6 parts in SL moulds.

Purpose: It was the aim of the present study to develop sustained-release matrix tablets by means of injection molding of ethylcellulose (EC) and polyethylene oxide (PEO) mixtures and to evaluate the influence of process temperature, matrix composition, and viscosity grade of EC and PEO on processability and drug release. Methods: Formulations consisting of metoprolol tartrate (MPT, concentration: 30%), EC plasticized by dibutyl sebacate, and PEO were extruded and consequently injection molded into tablets. The influence of process temperature (120degreeC and 140degreeC), matrix composition, viscosity grade of EC (4, 10, 20, 45, and 100 mPas) and PEO (7 x 106, 1 x 106, and 1 x 105 Mw) on processability and drug release was determined. Results: Formulations consisting of 70% EC and 30% MPT ...

Abstract in portuguese O processamento de termoplásticos através do processo de injeção representa o principal método de fabricação de peças plásticas. Limitações do processo de injeção convencional, principalmente quanto à matéria-prima e configuração e funcionamento das máquinas disponíveis, tornam inviável a produção de produtos com grande área projetada e pequena espessura, como janelas automotivas e alguns tipos de lentes. Paralelamente, o processo de injeção evolu (more) i continuamente e há uma série de novas tecnologias geradas a partir do processo original, dentre elas o processo de injeção-compressão. No presente trabalho, utilizando análise computacional, estudou-se a produção de lentes de policarbonato através de dois processos distintos: injeção convencional e processo de injeção-compressão. A seqüência de estudos envolveu basicamente os seguintes pontos: estudo do padrão de preenchimento com conseqüente otimização do processo de injeção-compressão quanto à formação de linha de emenda; estudo da janela de processo para ambos os casos e comparação de alguns parâmetros principalmente tensão de cisalhamento e força de fechamento, por se tratarem de fatores limitantes na produção de peças com grande área projetada. Os resultados para o caso estudado comprovam grande vantagem na utilização do processo de injeção-compressão. Abstract in english The injection-molding of thermoplastics is the main process used in the production of plastics parts. There are some limitations in the conventional injection process, specially related to raw materials, machines configuration and operation, which hamper fabrication of thin parts with large areas such as car windows and lenses. On the other hand, the process has been improved continuously with several new technologies, going beyond the conventional injection molding proce (more) ss, including the "injection-compression" process. In this paper, using CAE (computer aided engineering) technology, the author studied the production of PC lens by both processes: conventional injection molding and injection-compression molding. The studies were basically conducted in the following sequence: flow pattern study and optimization of the injection-compression process focusing on the weld line size, molding window study for both cases and comparison of several parameters, particularly shear stress and clamp force - as they are key parameters for the production of large-area parts. The results confirm the advantages of the injection-compression process.

A process combining cooling slope casting and suction casting was developed to generate a semisolid structure in a Zr-based bulk metallic glass matrix composite. The melt was injected onto a cooling slope and subsequently vacuum sucked into a cylindrical copper mold placed at the end of the slope. The structure obtained for 4-mm-diameter specimens of composition Zr66.4Nb6.4Cu10.5Ni8.7Al8 consists of a dispersion of spheroidal and rosettelike bcc crystals in a glassy matrix. Various slope angles, slope lengths, and injection pressures were tested. The coarsest and most spheroidal crystal structure was obtained at short slope lengths and high injection pressures. Microstructure analysis suggests that the slope is the location of extensive crystal nucleation and possible fragmentation, while the microstructure’s morphological evolution seems to occur mainly in the mold. The semisolid structure is expected to confer improved mechanical properties and ductility to the composite material.

Most clinical chemistry tests are performed on cell-free serum or plasma. Therefore micro assay devices for blood tests require integrated on-chip microfluidics for separation of plasma or serum from blood. Polymers are ideally suited for these applications due to their material properties and their applicability for high volume production. These requirements are achieved by a new on-chip blood separation technique based on microchannel bend structures and a rapid processing technology for micro assay devices using injection molding or hot embossing. Different prototype polymer chips with channel dimensions down to 20 ?m and aspect ratios of 4 have been fabricated by injection molding and hot embossing. The inserts for the molding tools were fabricated by an UV-LIGA technology. The separation efficiency of these chips has been tested with human blood samples. The results show different separation efficiencies up to 100 % for blood cells and plasma depending on microchannel geometry as well as cell concentration. As compared to present microfluidic devices for the separation of blood cells like filters, membranes or filtration by diffusion the microchannel bend is an integrated on-chip blood separation method. It combines the advantages of rapid separation times and a simple geometry that leads to cost-effective high volume production using injection molding.

Simulation of the injection molding process is a helpful way for the engineers who work with plastics processing. By simulation, they will get some important parameters which sometimes are highly necessary for the mold design and processing. Thus, the engineers will save much time to do experiments for the parameters. Two simulation programs are used in this report, namely CADMOULD and CADMOULD MEFISTO which are designed by Institut fur Kunststoffverarbeitung (IKV) in Aachen, W. Germany. CADMOULD works with 2-D geometry and is specialized for rheological, thermal and mechanical calculation. It is installed on a personal computer, while CADMOULD MEFISTO works in 3-D and is installed on a VAX 8530 computer at SINTEF. A PC version of this program is also available. This report deals with CADMOULD and CADMOULD MEFISTO. The construction of flow lines, balancing of sprue system, the optimizing of injection time, and gate(s) optimizing are mainly included.

RSP Tooling{trademark} is a spray forming technology tailored for producing molds and dies. The approach combines rapid solidification processing and net-shape materials processing in a single step. The general concept involves converting a mold design described by a CAD file to a tooling master using a suitable rapid prototyping (RP) technology such as stereolithography. A pattern transfer is made to a castable ceramic, typically alumina or fused silica (Figure 1). This is followed by spray forming a thick deposit of a tooling alloy on the pattern to capture the desired shape, surface texture, and detail. The resultant metal block is cooled to room temperature and separated from the pattern. The deposit's exterior walls are machined square, allowing it to be used as an insert in a standard mold base. The overall turnaround time for tooling is about 3 to 5 days, starting with a master. Molds and dies produced in this way have been used in high volume production runs in plastic injection molding and die casting. A Cooperative Research and Development Agreement (CRADA) between the Idaho National Engineering and Environmental Laboratory (INEEL) and Grupo Vitro has been established to evaluate the feasibility of using RSP Tooling technology for producing molds and dies of interest to Vitro. This report summarizes results from Phase I of this agreement, and describes work scope and budget for Phase I1 activities. The main objective in Phase I was to demonstrate the feasibility of applying the Rapid Solidification Process (RSP) Tooling method to produce molds for the manufacture of glass and other components of interest to Vitro. This objective was successfully achieved.

Abstract The main issue concerning poly(lactic acid) (PLA) has been its brittleness, thus limiting its potential to only a minute number of applications. Some attempts have been made to modify or blend PLA with tougher materials to improve its deformability, with varying degrees of success. This study primarily concentrates on enhancing the toughness of PLA without the incorporation of any additives whatsoever, thus the end product would consist of 100% biodegradable PLA. It is shown here that the toughness of PLA can be significantly enhanced by merely improvising processing techniques. The textile-insert molding technique was applied in this case, whereby PLA fabrics were attached to the surface of PLA resin by injection-compression molding. It was found that the molding conditions have ...

This study focuses on the injection molding of mechanical alloyed Ti–Fe–Zr alloys. Injection molded samples were produced using mechanical alloying based on hydride-dehydride (HDH) titanium and pure iron and zirconium powders. Mechanical alloyed powders were mixed with a polymeric binder and hot injection molded to form standard tensile bars. The critical powder loading for injection molding was 50 vol% for feedstock. Molded bars were debound by solvent and then thermal steps, under ultra pure argon. Debound samples were sintered at 1300°C for 60 min in a high level vacuum (10?5 mbar). After sintering, the performances of the sintered materials was characterized using tensile and hardness testing, optical microcopy (OM) and scanning electron microscopy (SEM). The strengths and weaknesses of the test conditions have been analyzed from the microstructure and mechanical properties. Theoretical density, ultimate tensile strength, and hardness of injection molded Ti powders increased with the additions of 5%Fe and 5%Zr.   

This thesis is concerned with the application of statistical methods in quality improvement of injection molded parts. The methods described are illustrated with data from the manufacturing of parts for a medical device. The emphasis has been on the variation between cavities in multi-cavity molds. >From analysis of quality measurements from a longer period of manufacturing, it was found that differences in cavities was that source of variation with greatest influence on the lenght of the molded parts. The other large contribution to the lenght varation was the different machine settings. Samples taken within the same machine set-point did not cause great variation compared to the two preceding sources of variation. A simple graphical approach is suggested for finding patterns in the cavity differences. Applying this method to data from a 16 cavity mold, a clear connection was found between a parts lenght and the producing cavitys position in the mold. In a designed expriment it was possible to isolate the machine parameters contributing to the variation beteeen cavities. Thus, with a proper choice of levels for the machine variables, it was possible to reduce the varation between cavities substantially. Also an alternative model for the shrinkage of parts from a multi-cavity mold is suggested. From applying the model to data from a shringage study, it seemed that the observed part differences were not only due to differences in cavity dimensions. A model for the in-control varation for a multi-cavity molding process was suggested. Based on this model, control charting proceures have been suggested for monitoring the quality of the molded parts. Moreover, a capability index for multi-cavity molds has been suggested. Furthermore an alternative method for in-line quality charting is suggested. The method is for continuous control by attributes, and it is an alternative to the batch oriented approach mostly used. The procedure is especially efficient for quality requirements of very low proportion non-conformities. For the proposed charts the ARL function is derived. It is shown that in the case where a non-conforning unit is only expected very rarely during sampling, a moving sum chart and a CUSUM chart are equivalent. Finally, the correlation structure of 21 process variables has been studied prior to monitoring the process. Is is illustrated how the process can be analysed with multivariate techniques. It was found that two principal components reflected changes in machine set-points. Thus, there seems to be great potential in monitoring the process variables using a multivariate approach.

During the past decade, enhanced processing has produced ceramic materials with improved mechanical properties and reliability. However, ceramic materials are still inherently brittle. Therefore, whisker-reinforced ceramic composites have recently received significant attention because of their attractive mechanical properties. In addition, the discrete nature and moderate aspect ratio of the short whiskers allow them to be processed into complex-shaped components, using automated fabrication methods, such as injection molding. Here, the compounding behavior of injection moldable silicon powder - SiC whisker formulations, for toughened reaction-bonded Si[sub 3]N[sub 4] composites, was examined as a function of the binder system. The effect on whisker degradation and orientation was also studied.

The ability to replicate the surface roughness from mold wall to the plastic part in injection moldning has many functional and cosmetic important implications from medical use to designer products. Generally the understanding of surface transcription i.e the the replication of the surface structure from the mould to plastic part, also relates to micro injection moulding and moulding of parts with specific micro structures on the surface such as optical parts. The present study concerns transcription of surface roughness as a function of process parameters. The study is carried out with a polystyrene part, process parameters at typical levels and a rough spark eroded mould surface with Ra=12.6 micro meters.

A pattern roll mold for imprinting 15-in. liquid crystal display black matrix was fabricated. A Ni sheet mold was replicated by electroforming process. For high accurate sheet mold wrapping process, a sheet mold wrapping machine was developed. Using the roll mold, black matrix patterns were manufactured by a roll-to-roll nanoimprint lithography system with high pattern uniformity. The electroformed Ni sheet mold has 0.01% dimensional error rate due to the thermal and internal stress. The radius variation of the roll increases by 2 ?m after wrapping the sheet mold. And alignment error in wrapping was 8.2×10?5 radian out of vertical line.   

The development of molecular orientation in thermotropic liquid crystalline polymers (TLCPs) during injection molding has been investigated using two-dimensional wide-angle X-ray scattering coordinated with numerical computations employing the Larson-Doi polydomain model. Orientation distributions were measured in 'short shot' moldings to characterize structural evolution prior to completion of mold filling, in both thin and thick rectangular plaques. Distinct orientation patterns are observed near the filling front. In particular, strong extension at the melt front results in nearly transverse molecular alignment. Far away from the flow front shear competes with extension to produce complex spatial distributions of orientation. The relative influence of shear is stronger in the thin plaque, producing orientation along the filling direction. Exploiting an analogy between the Larson-Doi model and a fiber orientation model, we test the ability of process simulation tools to predict TLCP orientation distributions during molding. Substantial discrepancies between model predictions and experimental measurements are found near the flow front in partially filled short shots, attributed to the limits of the Hele-Shaw approximation used in the computations. Much of the flow front effect is however 'washed out' by subsequent shear flow as mold filling progresses, leading to improved agreement between experiment and corresponding numerical predictions.

This project is intended to support plastics manufacturing being the important supporting industry in Thailand for manufacture of household electric appliances and automobiles, particularly the manufacture of engineering plastics having excellent heat and impact resistance. In order to achieve the target, a supporting system is being developed to allow injection molding of engineering plastics to be performed easily. The project aims particularly at developing a system that suits climate conditions in Thailand, properties of plastic materials procurable in Thailand, and skills of Thai engineers. The current fiscal year has carried out the following activities: evaluating materials required for the research and development, deciding the specifications for and ordering product evaluating and testing facilities, molds and mold cooling and heating adjustment devices, and an injection molding CAE system; these items were introduced and installed in Thailand; engineers were sent from Japan to perform technical guidance on operation, maintenance and management of the material and product evaluating and testing facilities, as well as joint researches; and Thai researchers were received to execute training on product evaluating and testing technologies, forming and processing technologies, and CAE utilizing technologies. (NEDO)

Kenaf (Hibiscus Cannabinus) is a fast growing annual growth plant that is harvested for its bast fibers. These fibers have excellent specific properties and have potential to be outstanding reinforcing fillers in plastics. In our experiments, the fibers and polypropylene (PP) were blended in a thermokinetic mixer and then injection molded, with the fiber weight fractions varying to 60%. A maleated polypropylene was used to improve the interaction and adhesion between the non-polar matrix and the polar lignocellulosic fibers. The specific tensile and flexural moduli of a 50 % by volume (39 % by volume) of kenaf-PP composites compares favorably with a 40 % by weight of glass fiber-PP injection molded composites, These results suggest that kenaf fibers are a viable alternative to inorganic/mineral based reinforcing fibers as long as the right processing conditions are used and for applications where the higher water absorption is not critical.

In this paper, we present in a first time a methodology used to determine the thermophysical properties and the crystallization kinetics of a thermoplastic reinforced composite (MXD6). A specific instrumented device was developed to allow the molding of the polymer in conditions as close as possible to those met in the injection process. Measurements during molding are used by two inverse problems to compute the thermal conductivity in melted and solid phases and the kinetic parameters. The estimated values of thermal conductivity are compared to a model based on the orientation of the fibers through the thickness. Results from kinetics are compared to literature one. Heat transfers are then studied during the injection by using an instrumented mould. It is shown that during filling the he...

In the field of micro-technology the production of metallic and ceramic micro-components by powder injection molding (PIM) has become a more and more established fabrication method. But in order to fulfill the demand for more complex-shaped high-precision micro-components further development work has to be performed. This is especially true if more efficient production routes for multi-component-micro-assemblies consisting of different materials or sub-components are envisaged. To meet these challenges, investigations are performed to realize and to establish two primary shape micro-processes. These are two-component micro-injection molding (2C-MicroPIM) and sinter-joining. The realization of these technologies will lead to a markedly reduction of the efforts for handling, adjustment, and ...

Surface feature optics, including binary optics, sinusoidal gratings, and high-fill factor micro- lens arrays, are being intensively developed for use in beam splitting and optical computing. Most are fabricated in plastics, and are therefore subject to such general disadvantages as limited optical transmission and high CTE. Some can be scribed in silica but dimensions are limited and fabrication costs are extremely high. Using a sol-gel process it is possible to fabricate surface feature optics in pure silica by a room-temperature molding technique. This technique provides the advantage of the highly favorable optical qualities of silica, including broadband transmission, low CTE, and exceptional resistance to laser damage. The sol-gel process is a room temperature casting operation in which the glass replicates the surface of the mold. Molds used in the sol-gel process can be fabricated from plastics and epoxies using common injection molding and press forming operations or via more sophisticated techniques. The manufacture of several prototypes is reported in terms of processing and characterization to determine the fidelity of the replication and their ability to fulfill required optical specifications.

Fabrication of polymer microfluidics devices such as micromixer by injection molding becomes popular increasingly. It is always involved with the replication of micro-channels for fluids. The quality control of the produced micro-channels is a key issue in the microfluidics devices fabrication. This paper studies the effects of processing conditions on the cross-sectional profile and the dimensions of the micro-channel such as its width and depth. Design of experiment (DOE) using Taguchi method and a L18 (21??37) orthogonal array is used to carry out the optimization of the processing conditions in order to achieve the closest micro-channel width to the micro-feature width of the mold insert. Eight processing parameters are considered in DOE and their significances are investigated in ana...

This paper applies a recently developed model to predict the elastic-plastic stress/strain response and strength of injection-molded long-fiber thermoplastics (LFTs). The model combines a micro-macro constitutive modeling approach with experimental characterization and modeling of the composite microstructure to determine the composite stress/strain response and strength. Specifically, it accounts for elastic fibers embedded in a thermoplastic resin that exhibits the elastic-plastic behavior obeying the Ramberg-Osgood relation and J-2 deformation theory of plasticity. It also accounts for fiber length, orientation and volume fraction distributions in the composite formed by the injection-molding process. Injection-molded-long-glass-fiber/polypropylene (PP) specimens were prepared for mechanical characterization and testing. Fiber length, orientation, and volume fraction distributions were then measured at some selected locations for use in the computation. Fiber orientations in these specimens were also predicted using an anisotropic rotary diffusion model developed for LFTs. The stress-strain response of the as-formed composite was computed by an incremental procedure that uses the Eshelby’s equivalent inclusion method, the Mori-Tanaka assumption and a fiber orientation averaging technique. The model has been validated against the experimental stress-strain results obtained for these long-glass-fiber/PP specimens.

  In order to develop the near net shaping process of austenitic stainless steels (UNS : s30400) by semi-solid extrusion forming process, microstructure controlling technology and forming technology of this material in the semi-solid state were investigated. Effects of forming temperature, forming rate, and forming pressure on the form ability of its slurry into a metallic mold were studied. Rapid heating of the material before forming into the mold is needed to avoid coarsening of grains in the semi-solid state, but no homogeneous temperature distribution and homogeneous microstructure are obtained. In the case of rapid forming, the liquid phase is injected into the mold preferentially and segregation of the solid and liquid phases occurs. In the case of slow forming, such segregation does not occur, but good fulfillment is not obtained because of rapid cooling caused by sufficient contact with the metallic mold. When these parameters are optimized, defect-free formings are obtained, as are good surface products. By using a stainless steel wire net in place of a multi-hole die, high fluidity and homogeneous microstructures are obtained even at low forming rates. Two- or three-dimensional shape plates can also be formed by optimizing these parameters.   

Resin transfer molding (RTM) is a common composite manufacturing process. Voids are a common defect encountered in RTM components. A new type of void, the 'Mega-Void', has been identified and addressed by this research. To produce acceptable RTM components requires that the mega-void be eliminated either through prevention or through dissolution. The latter is the topic of this research. Three process parameters affecting mega-void dissolution are researched; (1) Preform/mold vacuum, (2) Resin degas, and (3) Resin curing pressure. To address preform/mold vacuum, analytical and empirical investigations were carried out. Results show that the preform can take-up and retain water. Additional analytical investigations show that gas flow within the preform is molecular in nature. The consequence of this finding is that the removal of moisture and gases from the preform is difficult. Confirming experiments were carried out showing a significant difference between gas pressures within the mold and the gas pressure external to the mold. The resin degas and resin curing pressure parameters were studied by researching the solubility of air in epoxy. An experimental apparatus was designed and fabricated wherein a sample of resin could be subjected to a specified level of vacuum for degassing. Subsequently, a measured amount of air was introduced into the resin sample and the combination pressurized to a controlled pressure. The resin and air were then monitored over time to observe the shrinkage of the air pocket as the air was absorbed by the resin. The experimental results show the pressure of residual air and the resin dissolution pressure both significantly affect the absorption of the air pocket. Higher levels of resin degassing are shown to provide a small benefit to gas dissolution. As a final research effort, composite panels were fabricated using a blind injection setup where a single mold port is used for evacuation and resin injection. In this way, the starting size of the mega-void is fixed and equal to the mold free volume. The three processing parameters were varied in order to show the dissolution of mega-voids when the appropriate parameters are used.

Molecular dynamics studies are carried out to investigate the deformation mechanism of glass materials for nanoimprint lithography (NIL). The filling process of glass into the mold cavity and the stick slip phenomena during the mold release are investigated in atomic scale. The relationship between displacement of the mold and applied pressure to the mold are evaluated in NIL including both deformation and demolding processes. The dependence of the required pressure for full filling on the glass thickness and the line width of the mold cavity are investigated. In addition, fracture of glass pattern during the mold release is studied.   

Various types of barrier ribs for a plasma display panel were formed via a capillary molding process. A thermosetting paste was filled into cavities of working molds by means of capillary action and was cured prior to removal of the molds. The working molds were prepared by curing liquid polydimethylsiloxane on master molds that were produced from a photoresist. It was demonstrated that various types of barrier ribs could be produced successfully by sintering the ribs formed by the molding process. In addition, the effects of solid loading in the paste, prefiring temperature and type of barrier ribs on the morphologies of the ribs were investigated.   

For over ten years, injection molding and slip casting have been actively developed as forming techniques for ceramic gas turbine components. Co-development of these two processes has continued within the U.S. DOE-sponsored Advanced Turbine Technology Application Project (ATTAP). Progress within ATTAP with respect to these two techniques is summarized. A critique and comparison of the two processes are given. Critical aspects of both processes with respect to size, dimensional control, material properties, quality, cost, and potential for manufacturing scale-up are discussed.

Abstract Starch as an inexpensive and renewable source has been used as a filler for environmental friendly plastics for about two decades. In this study, glycerol was used as a plasticizer for starch to enhance the dispersion and the interfacial affinity in thermoplastic starch (TPS)/polybutene-1(PB-1) blend. PB-1 was melt blended with TPS using a single screw extrusion process and molded using injection molding process to investigate the rheological and mechanical properties of these blends. Rheological properties were studied using a capillary rheometer, and the Bagley's correction was performed. Mechanical analysis (stress-strain curves) was performed using Testometric M350-10 kN. The rheological properties showed that the melt viscosity of the blend is less than that of PB-1, and the ...

This paper has investigated the fabrication process of porous Ni?YSZ anodes by the powder injection molding method, in which a powder space holder (PSH) is used. Polymethyl methacrylate (PMMA) has been used as a PSH for mixing with NiO?YSZ powders. For this study, five kinds of feedstock containing 0%, 10%, 20%, 30%, and 40% PMMA by volume were prepared. The thermoplastic binder used for the process had a fixed 35 vol.%, and the powder loads formed the remaining 65, 55, 45, 35, and 25 vol.% of the feedstock. After molding and debinding, the parts were sintered at 1,500 °C. The obtained results showed that increasing the PMMA portion of the feedstock and reducing its powder load causes the viscosity of the feedstock to decrease. The amount of shrinkage of the samples containing 0?30% PMMA s...

On production of sintered Co-Cr-W-C alloy using metal injection molding (MIM) process, effect of debinding and various conditions in the sintering process on the carbon content, microstructure and mechanical properties of the sintered compact was examined. Powders of Co, Cr, Cr3C2 and W mixed in a wet mill were dried. Mixed powder and waxy binder in equal volume were mixed and heated, and molded into specimens. Sixty-five wt% of the binder was extracted in the heptane gas, and the residual binder was dissipated under heating in the H2 and N2 mixture gas. It was shown that carbon content was variously controlled with change of gas compositions. The following coexisting phases were observed in the sintered compact: Co-phase, {eta}(Co3W3C) phase, M23C6 phase and M7C3 phase. Injection molded alloys showed almost the same microstructure and mechanical properties as those of conventional powder metallurgy alloys. Possibility of application of MIM with excellent moldability was shown in sintered Co-Cr-W-C alloy. 3 refs., 7 figs., 1 tab.

High-tensile brass was used to make molding die for injection by casting it into the ceramic permeable mold. The transprinting attribute is mainly dependent on the sucking pressure. In sucked cases, all of the patterns are transprinted clearly and have very good sense of reality. The effect of sucked casting on roughness of plane is also obvious. Defects, like pinholes and gas pores which are resulted from air and gas at the interface, appear under non-sucked condition, but the defects can not be observed in sucked cases. Various kinds of molding dies suck-cast so far are shown. Every alloy can be cast successfully and each kind of patterns can be transprinted perfectly. The finest triangle wave has the angle of 102 {degree}, pitch of 88 {mu} m, the size of which is close to that of a groove of music record. Comparison of the used alloys on their mechanical and other properties is made. Molding die having patterns can be produced by this process with high quality and precision at low cost in relatively short time. 3 refs., 4 figs., 1 tab.

A process in which lightweight, highly accurate, economical molds can be produced for prototype and low production runs of large parts for use in composites molding has been developed. This has been achieved by developing existing milling technology, using new materials and innovative material applications to CNC mill large female molds directly. Any step that can be eliminated in the mold building process translates into savings in tooling costs through reduced labor and material requirements.

The paper is concerned with optimization and parametric identification of Powder Injection Molding process that consists first in injection of powder mixture with polymer binder and then to the sintering of the resulting powders parts by solid state diffusion. In the first part, one describes an original methodology to optimize the injection stage based on the combination of Design Of Experiments and an adaptive Response Surface Modeling. Then the second part of the paper describes the identification strategy that one proposes for the sintering stage, using the identification of sintering parameters from dilatometer curves followed by the optimization of the sintering process. The proposed approaches are applied to the optimization for manufacturing of a ceramic femoral implant. One demonstrates that the proposed approach give satisfactory results.

The effects of two different rheological models used in the simulation of the micro injection molding (µIM) process are investigated. The Cross-WLF viscous model and the Giesekus viscoelastic model are selected and their performance evaluated using 3D models implemented on two different commercially available software packages. Simulation results are then compared with the experimental µIM process. Validation parameters for the comparison are the flow front position during filling of the micro cavity. They are respectively obtained by applying the short-shots method and the flow-markers method. The µIM part is a polystyrene tensile bar test weighting 20mg and with three µ-features 300µm wide.

Fully biobased composite materials were fabricated using a natural, lignocellulosic filler, namely oak wood flour (OWF), as particle reinforcement in a biosynthesized microbial polyester matrix derived from poly(@b-hydroxybutyrate)-co-poly(@b-hydroxyvalerate) (PHBV) via an extrusion injection molding process. The mechanisms and effects of processing, filler volume percent (vol%), a silane coupling agent, and a maleic anhydride (MA) grafting technique on polymer and composite morphologies and tensile mechanical properties were investigated and substantiated through calorimetry testing, scanning electron microscopy, and micromechanical modeling of initial composite stiffness. The addition of 46vol% silane-treated OWF improved the tensile modulus of neat PHBV by 165%. Similarly, the tensile m...

Current ceramic materials, component fabrication processes, and reliability prediction capability for ceramic stators in an automotive gas turbine engine environment are assessed. Simulated engine duty cycle testing of stators conducted at temperatures up to 1093 C is discussed. Materials evaluated are SiC and Si3N4 fabricated from two near-net-shape processes: slip casting and injection molding. Stators for durability cycle evaluation and test specimens for material property characterization, and reliability prediction model prepared to predict stator performance in the simulated engine environment are considered. The status and description of the work performed for the reliability prediction modeling, stator fabrication, material property characterization, and ceramic stator evaluation efforts are reported.

The effect of a tie film consisted of polyethylene (PE) and maleic anhydride functionalized PE (PE-g-MAH) on the interfacial adhesion of PE and polymide-6 (PA6) was studied in a sequential injection molding process. It was found that the interfacial adhesion of PE/PA6 was significantly improved via in situ reactive compatibilization. The results showed that the interfacial adhesion increased with PE-g-MAH concentration, and reached a plateau value at the weight fraction of 40%, showed a maximum at a thickness of about 15 mm tie film. Higher the second melt and mold temperature, stronger the interfacial adhesion was obtained. An analysis conducted on the fracture interface by using scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) revealed that the increase of t...

Automotive safety restraint system components increasingly use flexible styrenic and olefinic TPEs. With continued evolution in automotive interior design and performance requirements, demands on material technology are concomitantly rising. A growing trend towards molded in color solutions with low gloss aesthetics require TPE materials with ery low gloss, improved scratch resistance, and low temperature ductility. Innovations utilizing Teknor Apex's compounding technology have enabled the development of low gloss styrenic elastomers for airbag door applications that provide an optimized combination of low temperature performance, surface aesthetics (low gloss and improved scratch resistance), and ease of processing. This paper highlights the salient features of these new compounds and the effect of injection molding condition on the gloss at the surface of the cover.

Replica microchips for capillary array electrophoresis containing 10 separation channels (50 microm width, 50 microm depth and 100 microm pitch) and a network of sacrificial channels (100 microm width and 50 microm depth) were successfully fabricated on a poly(methyl methacrylate) (PMMA) substrate by injection molding. The strategy involved development of moving mask deep X-ray lithography to fabricate an array of channels with inclined channel sidewalls. A slight inclination of channel sidewalls, which can not be fabricated by conventional deep X-ray lithography, is highly required to ensure the release of replicated polymer chips from a mold. Moreover, the sealing of molded PMMA multichannel chips with a PMMA cover film was achieved by a novel bonding technique involving adhesive printing and a network of sacrificial channels. An adhesive printing process enables us to precisely control the thickness of an adhesive layer, and a network of sacrificial channels makes it possible to remove air bubbles and an excess adhesive, which are crucial to achieving perfect sealing of replica PMMA chips with well-defined channel and injection structures. A CCD camera equipped with an image intensifier was used to simultaneously monitor electrophoretic separations in ten micro-channels with laser-induced fluorescence detection. High-speed and high-throughput separations of a 100 bp DNA ladder and phi X174 Hae III DNA restriction fragments have been demonstrated using a 10-channel PMMA chip. The current work establishes the feasibility of mass production of PMMA multichannel chips at a cost-effective basis. PMID:15791347

The investment casting process is an expendable mold process where wax patterns of the part and rigging are molded, assembled, shelled and melted to produce a ceramic mold matching the shape of the component to be cast. Investment casting is an important manufacturing method for critical parts because of the ability to maintain dimensional shape and tolerances. However, these tolerances can be easily exceeded if the molding components do not maintain their individual shapes well. In the investment casting process there are several opportunities for the final casting shape to not maintain the intended size and shape, such as shrinkage of the wax in the injection tool, the modification of the shape during shell heating, and with the thermal shrink and distortion in the casting process. Studies have been completed to look at the casting and shell distortions through the process in earlier phases of this project. Dr. Adrian Sabau at Oak Ridge National Labs performed characterizations and validations of 17-4 PH stainless steel in primarily fused silica shell systems with good agreement between analysis results and experimental data. Further tasks provided material property measurements of wax and methodology for employing a viscoelastic definition of wax materials into software. The final set of tasks involved the implementation of the findings into the commercial casting analysis software ProCAST, owned and maintained by ESI Group. This included: o the transfer of the wax material property data from its raw form into separate temperature-dependent thermophysical and mechanical property datasets o adding this wax material property data into an easily viewable and modifiable user interface within the pre-processing application of the ProCAST suite, namely PreCAST o and validating the data and viscoelastic wax model with respect to experimental results

Described herein is a process for fabricating microfluidic systems with embedded components in which micron-scale features are molded into the polymeric material polydimethylsiloxane (PDMS). Micromachining is used to create a mold master and the liquid precursors for PDMS are poured over the mold and allowed to cure. The PDMS is then removed form the mold and bonded to another material such as PDMS, glass, or silicon after a simple surface preparation step to form sealed microchannels.

Improved ceramic-processing methods that use pressure slip-casting and injection molding are being developed at Norton Advanced Ceramics, with a goal of producing reliable structural ceramics for advanced heat engines. Nondestructive evaluation (NDE) of ceramic parts at different stages of processing can provide useful diagnostic information to help improve processing techniques. For example, an evaluation of density gradients in as-cast green-body samples can be used to judge mold performance and make changes in mold design. Also, the ability to detect minute flaws (20 to 50 {mu}m), such as agglomerates, inclusions, and voids, in green-body, presintered, and densified parts is important in ensuring structural reliability of the final parts, because these flaws, above certain critical sizes, can lead to catastrophic failure. Three-dimensional microfocus X-ray computed tomography (CT) and nuclear magnetic resonance imaging (MRI) systems have been developed at Argonne National Laboratory (ANL) for application to quantitative NDE evaluation of ceramics. This paper evaluates the detection sensitivity of the ANL X-ray CT system when used to determine density gradients, inclusions, and voids in green-state Si{sub 3}N{sub 4} ceramics. A theoretical account of key system- and sample-related parameters affecting X-ray CT detection sensitivity is given, and results of experimental evaluation are presented. Density calibration phantoms and net-shape-formed tensile rods with seeded defects were used in the experimental evaluation of detection limits. 6 refs., 6 figs., 1 tab.

We present a novel method to fabricate an all in polymer injection molded chip for electrochemical cell recordings and lateral cell trapping. The complete device is molded in thermoplastic polymer and it results from assembling two halves. We tested spin-coated conductive polymer poly(3,4-ethylenedioxythiopene) and showed that it can be used as an electrode material for detecting neurotransmitters electrochemically in biosensors.

A rapid wax injection tool of a gearbox shift fork was designed, simulated, and manufactured using rapid prototyping and rapid tooling technology to save time and cost of producing wax models used for the investment casting process. CAE simulation softwares, in particular, MoldFlow, are used to get wax injection moulding parameters such as filling parameters, temperature profiles, freeze time, speed, and pressure. The results of this research were compared with conventional wax model production methods. The criteria of such comparison were based upon parameters such as time, cost, and other related characteristics, which resulted in saving of 50% in time and 60% in cost. In this research, design, assembly, and wax injection operation of the wax tool took 10 days. Considering the fact that ...

Mold powder plays an important role in the continuous casting process for high quality steel production. Qualitatively, it is well known that mold powder entrapment causes surface defects in steel sheets, and high viscosity of the mold powder prevents the entrapment of the mold powder into the molten steel in ultra-low carbon steel.This paper deals quantitatively with the entrapment of mold powder caused by suction by Karman's vortex in a laboratory experiment. First, in a water model experiment using oil as a substitute for mold powder, the effects of the viscosity of the oil and the interfacial tension between the water and oil were investigated. Following this, hot model experiments were carried out with mold powder and molten steel. The amount of mold powder entrapment was affected by the viscosity of the molten mold powder and the interfacial tension between the molten steel and mold powder. As the result, the following equation for mold powder entrapment was obtained.m=1.06×107??0.255?m–s?2.18where m: weight of entrapped mold powder (g/100 g-steel), ?: viscosity of mold powder at 1573 K (Pa·s), and ?m–s: interfacial tension between molten steel and mold powder (mN/m).The amount of mold powder entrapment decreased when the viscosity and interfacial tension increased. However, the effect of viscosity on mold powder entrapment was larger than that of interfacial tension in the case of an industrial mold powder when viscosity was under 0.5 Pa·s and interfacial tension was from 1200 to 1300 mN/m.   

Until now the utilization of plastics for exterior parts of automobiles has been mainly limited to front and rear ends using polyurethane (PUR), sMC or modified polypropylene (PP-EPDM). Saving energy by reducing vehicles' weight and optimizing their drag coefficients (csub(w) values) is the most important goal in modern motor vehicle development. In addition, it is necessary to observe the safety regulations in force and to make production more cost-efficient. Thermoplastic parts can be processed economically by injection-molding, but their characteristics must be improved. Improvements must be aimed at their stability in environments containing gasoline and developing heat; impact strength at low temperatures, paintability and dimensional stability.

The mechanical responses including monotonic and cyclic tensile responses have been investigated on a microphase-separated poly (styrene-isoprene-styrene) triblock copolymer (SIS). The specimens were injection-molded by using different melt temperatures to acquire different microphase structures. As a result of temperature-dependent segregation driving force, the specimens with reduced microphase separation can be obtained by increasing processing melt temperature from 180 degreeC to 240 degreeC. On the basis of stress-strain behavior, Youngs modulus was found to increase with increasing PS domain continuity in the order of disorder state to disordered spheres to body-cubic-centered (BCC) spheres to oriented cylinders morphology. Meanwhile, cyclic hysteresis decreases with reduced micropha...

In this paper, short carbon fiber reinforced nylon spur gear pairs, and steel and unreinforced nylon spur gear pairs have been selected for study and comparison. A 3D finite element model was developed to simulate the multi-axial stress-strain behaviors of the gear tooth. Failure prediction has been conducted based on the different failure criteria, including Tsai-Wu criterion. The tooth roots, where has stress concentration and the potential for failure, have been carefully investigated. The modeling results show that the short carbon fiber reinforced nylon gear fabricated by properly controlled injection molding processes can provide higher strength and better performance.

The insufficient entanglement of the molecular chains and the stress amplification at the v-notch of a weld line compromise the mechanical strength of a plastic product, also in the micro scale. To investigate the influence of process parameters on the weld lines formation, a special micro cavity was designed and manufactured by µEDM (Electro Discharge Machining). Weld lines were quantitatively characterized both in the two-dimensional (direction and position) and three-dimensional range (surface topography characterization). Results showed that shape and position of weld lines are mainly influenced by mold temperature and injection speed.

For micro/nanoimprinting of glass, the appropriate combination of glass and mold material was clarified by an adhesion test using chemical vapor deposition (CVD) diamond, silicon, glassy carbon and sintered nitride ceramics as the mold material, and Pyrex, TEMPAX and BK7 as the glass material. The result of the adhesion test shows that CVD diamond is suitable for imprinting with a wide variety of glass materials under various temperature conditions. The method of fabricating the CVD diamond mold using focused ion beam (FIB) was examined, and it was clarified that the grain boundary of CVD diamond has little effect on the surface condition. Glass micro/nanoimprinting was performed using the CVD diamond mold. The effect of the molding conditions, such as the molding temperature and mold-release temperature, on the height of glass transcription was clarified. The effects of pattern size and shape were also investigated. On the basis of the results, a method of selecting the molding conditions to obtain the desired transcript height was developed. In this research, the entire flow of glass micro/nanoimprinting, including mold material selection, the mold fabrication process and molding process, was proposed experimentally, and the selection method of the molding conditions was shown.

Microfabricated single-cell capture and DNA stretching devices have been produced by injection molding. The fabrication scheme employed deep reactive ion etching in a silicon substrate, electroplating in nickel and molding in cyclic olefin polymer. This work proposes technical solutions to fabrication challenges associated with chip sealing and demolding of polymer high-volume replication methods. UV-assisted thermal bonding was found to ensure a strong seal of the microstructures in the molded part without altering the geometry of the channels. In the DNA stretching device, a low aspect ratio nanoslit (1/200) connecting two larger micro-channels was used to stretch a 168.5 kbp DNA molecule, while in the other device single-HeLa cells were captured against a micro-aperture connecting two larger microfluidic channels. Different dry etching processes have been investigated for the master origination of the cell-capture device. The combination of a modified Bosch process and an isotropic polysilicon etch was found to ensure the ease of demolding by resulting in slightly positively tapered sidewalls with negligible undercut at the mask interface.

To address the cost and performance barriers which hinder the introduction of composite materials for combat ground vehicle applications, Co-Injection Resin Transfer Molding (CIRTM) and Diffusion Enhanced Adhesion (DEA) have been recently invented and developed at the Army Resear...

Oct 26, 1982 ... consisting of silicon nitride powder and a densification aid. The reaction ... open porosity originally found in the reaction bonded .... h as silicon particles are injection that I am ... This mixture is slip cast into a plaster mold.

(e.g. injection molding) or becomes optimized and rationalized through such additives. ... porosity into the furnace space. - oxidation of these gases in the furnace space ..... powder in a platinum crucible. The heating dm3/min rate was. 5 K/min ...

were improved by using high purity powder and a stabilized Zr02 additive,. (2) Impact ..... methods such as slip casting, cold pressing, or injection molding. ... a consequence of its porosity, RSSN has much lower room temperature strength ...

havior of the powder blends during pressure sintering was determined by ... or injection molding is used for RSSN parts in comparison to the more expensive hot- ... materials of low porosity (viz 7 percent) evoked considerable interest.

A compound formulation having good abrasion resistance and flex crack resistance was developed for a combat boot outsole. The lightweight polyurethane has a specific gravity of 0.55. To fabricate the outsole, liquid injection molding equipment was used. I...

Disclosed is a molten metal injector system including a holder furnace, a casting mold supported above the holder furnace, and a molten metal injector supported from a bottom side of the mold. The holder furnace contains a supply of molten metal having a metal oxide film surface. The bottom side of the mold faces the holder furnace. The mold defines a mold cavity for receiving the molten metal from the holder furnace. The injector projects into the holder furnace and is in fluid communication with the mold cavity. The injector includes a piston positioned within a piston cavity defined by a cylinder for pumping the molten metal upward from the holder furnace and injecting the molten metal into the mold cavity under pressure. The piston and cylinder are at least partially submerged in the molten metal when the holder furnace contains the molten metal. The cylinder further includes a molten metal intake for receiving the molten metal into the piston cavity. The molten metal intake is located below the metal oxide film surface of the molten metal when the holder furnace contains the molten metal. A method of injecting molten metal into a mold cavity of a casting mold is also disclosed.

It is noted that with traditional foam casting under pressure technology the casting mold chamber formed during injection of molten polymer material (PM) is only partly filled with the mixture of melt and gas-former, but total filling of the chamber occurs during melt foaming. In this stage, the pressure of the forming gas governs the magnitude of the internal pressure in the casting mold. It is demonstrated that due to the relatively low pressure and bubble formation during mold filling it is impossible to obtain a component with a high quality surface. In order to avoid this disadvantage, the following are developed: ?breathing?? casting molds; a method using a gas counterpressure in the mold; special coatings for forming the casting mold surface, reducing temperature oscillation and smo...

A study of the flow behavior during sequential co-injection molding is shown using a three-dimensional finite element flow analysis code. Solutions of the non-Newtonian, non-isothermal melt flow are obtained by solving the momentum, continuity and energy equations. Two additional transport equations are solved for tracking polymer/air and skin/core polymers interfaces. The co-injection model is integrated into the NRC's 3D injection molding software. Solutions are shown for the filling of a spiral-flow mould for which experimental measurements are available. The numerical approach predicts the core advance stage during which the core flow front catches up on the skin flow front and the core expansion phase when the flow fronts of core and skin materials advance together without breakthrough. The breakthrough phenomenon is also predicted. The predicted flow front behavior is compared to the experimental observations for various skin/core melt temperature and skin/core viscosity ratio. Simulation results are in good agreement with experimental data and indicate correctly the trends in solution change when processing parameters are changing.

This paper introduces the development of a double-sided micro lens array (DSMLA) for application in micro laser projectors. For commercial mass production, it is necessary to investigate the concurrent engineering of optical design, mold fabrication, and plastic injection molding at once. This experiment based the design of the micro lens array on the scalar diffraction theory. The proposed DSMLA can simultaneously shape red, green, and blue laser beams into a uniform projection pattern. An ultra precision diamond turning machine using a slow tool servo method fabricated the mold. The study considered optical design constraints from the feedback of mold fabrication and plastic injection molding, measuring and comparing fabricated samples with calculated results. Experimental results show that the fabricated DSMLAs achieve the desired function and application feasibility for micro laser projectors.

Work performed to develop silicon carbide materials of high strength and to form components of complex shape and high reliability is described. A beta-SiC powder and binder system was adapted to the injection molding process and procedures and process parameters developed capable of providing a sintered silicon carbide material with improved properties. The initial effort has been to characterize the baseline precursor materials (beta silicon carbide powder and boron and carbon sintering aids), develop mixing and injection molding procedures for fabricating test bars, and characterize the properties of the sintered materials. Parallel studies of various mixing, dewaxing, and sintering procedures have been carried out in order to distinguish process routes for improving material properties. A total of 276 MOR bars of the baseline material have been molded, and 122 bars have been fully processed to a sinter density of approximately 95 percent. The material has a mean MOR room temperature strength of 43.31 ksi (299 MPa), a Weibull characteristic strength of 45.8 ksi (315 MPa), and a Weibull modulus of 8.0. Mean values of the MOR strengths at 1000, 1200, and 14000 C are 41.4, 43.2, and 47.2 ksi, respectively. Strength controlling flaws in this material were found to consist of regions of high porosity and were attributed to agglomerates originating in the initial mixing procedures. The mean stress rupture lift at 1400 C of five samples tested at 172 MPa (25 ksi) stress was 62 hours and at 207 MPa (30 ksi) stress was 14 hours. New fluid mixing techniques have been developed which significantly reduce flaw size and improve the strength of the material. Initial MOR tests indicate the strength of the fluid-mixed material exceeds the baseline property by more than 33 percent.

  The effects of injection speed on the cast properties were first investigated. High injection speeds were found to cause a high degree of air entrapment in the casting which reduced the casting quality, such as mechanical properties and density. Secondly, water model experiments using transparent molds were performed to clarify the relationship between the mold filling flow characteristics and the injection speed. A critical injection speed, below which no air entrapment occurred, was found to exist, and its value was 0.5m/s. Furthermore, pre-charge in a mold prior to high speed injection was found to be effective for preventing air entrapment. The relationship of the amount of pre-charge required and the injection speed was determined from a series of water model experiments.   

Ti and its alloys have been widely used for various industrial and medical applications because of their excellent characteristics of low density, high strength, high corrosion resistance and high biocompatibility. However, it is not easy to produce the complicated shape and precise parts because of their poor workability. Therefore, the advanced powder processing techniques such as Metal Injection Molding (MIM) are hoped to be a suitable technique for fabricating complex shaped Ti or its alloy parts with low cost. In this paper, various high performance Ti alloy materials such as Ti-6Al-4V added Mo or Fe or Cr have been developed by MIM process. The effect of powder type and sintering conditions on the microstructures, relative density and mechanical properties of injection molded compacts were investigated. Also the oxygen and carbon contents were checked in detail for obtaining high performance properties as same as the wrought materials. Eventually, more than 1000MPa of strength and 15% of elongation were achieved with MIM process.   

Taguchi method of L27 (313) orthogonal array is used in this paper as a tool in optimization of Metal injection molding (MIM) parameters for the highest green strength. Parameters optimized are the injection pressure, injection temperature, powder loading, mold temperature, holding pressure and injection speed. Besides those, interaction of the injection pressure, injection temperature and powder loading were studied. The metal powder of Ti-6Al-4V is mixed with binder 60wt% of palm stearin and 40wt% of polyethylene successfully injected at optimum parameter condition: 350 bar of injection pressure, 140° C of injection temperature, 65vol% of powder loading, 50° C of mold temperature, 600 bar of holding pressure, and 10 ccm/s of the injection rate. Analysis of variance (ANOVA) for the best signal to noise ratio (S/N) presents the contribution of the parameters to the quality characteristic (green strength). Results show that the mold temperature has highest significant percentage (27.59%) followed by powder loading (15.44%) and injection pressure (12.30%). Nevertheless, the analysis of variance does not show any contribution from interaction.

A high-thermal-resistance polymer-based flexible imprint mold was developed to be used in a hot embossing process. This mold was readily replicated in a UV curing imprint process and can be used as a mold for hot embossing and thermally curing imprint processes. The nano-sized pattern of this mold was not degraded by soaking at 350 degrees C for 10 min and the pattern fidelity was maintained after 10 separate cyclic heating tests between 0 degrees C and 350 degrees C. The substrate of this flexible mold was PI film, and a UV-cured polyurethane acrylate (PUA) layer was used to form the nano-scale patterns. The durability of this polymeric mold was tested by repetitive hot embossing processes. Nano-scale patterns of the mold were readily transferred to a PMMA layer coated onto a Si substrate by hot embossing lithography at 180 degrees C. After 10 cycles of hot embossing processes, no damage or degradation was observed in the flexible polymer mold. Using this polymer mold, patterns as small as 50 nm were successfully transferred to a Si substrate. Due to the flexibility of the polymer mold, nano-scale patterns were successfully transferred to a non-flat acryl substrate by hot embossing lithography. PMID:22849136

We have developed a new type of semi-solid injection process that can obtain a high material yield of about 90% for magnesium alloys. The morphology of the solid particles in the semi-solid slurry has significant effects on the rheological behavior. In this study, semi-solid injection moldings of AZ91D magnesium alloy were conducted with injection speeds of 220, 300, and 400 mm/s and for fraction solids of fs = 0.3, 0.4, and 0.5 in order to investigate the effects of shear stress on the microstructure. With a high injection speed, the ?-phase solid particles became spherical and the average particle size decreased. The average roundness of the ?-phase solid particles was correlated to the shear stress calculated on the assumption that the slurry characteristics correspond to that of the steady state at the nozzle. The reduction of the average particle size suggests that the solid particles were broken up and spheroidized by the shear stress. Under all experimental conditions, the ?-phase particles in the plane perpendicular to the flow direction were concentrated at the center of specimen rather than on the surface. On the other hand, distribution of the ?-phase particles in the plane parallel to the flow direction depended on the injection speed. A high fraction solid zone was generated at the end of the specimen for a high injection speed.   

This work applies modular design concepts to designating beverage-container injection molds. This study aims to develop a method of controlling costs and time in relation to mold development, and also to improve product design. This investigation comprises two parts: functionality coding, and establishing a standard operation procedure, specifically designed for beverage-container injection mold design and manufacturing. First, the injection mold is divided into several modules, each with a specific function. Each module is further divided into several structural units possessing sub-function or sub-sub-function. Next, dimensions and specifications of each unit are standardized and a compatible interface is constructed linking relevant units. This work employs a cup-shaped beverage contain...

AGT-5 gasifier vane seat platforms with 14 vane pockets were fabricated by Ceramics Process Systems Corporation under contract to GM-Allison for the US Department of Energy sponsored ATTAP program. A newly developed SiAlon, engineered for gas turbine engine use at 1370{degrees}C, was formed into the component using the Quickset{trademark} injection molding process followed by pressureless sintering. The as-sintered components gave average 4-point flexural strengths of 102 kpsi at 25{degrees}C, 80 kpsi at 1000{degrees}C, 73 kpsi at 1200{degrees}C, 67 kpsi at 1300{degrees}C and 53 kpsi at 1370{degrees}C. Injection molded billet strengths were similar except at 1370{degrees}C where the average flexural strength was 72 kpsi. Creep rates at secondary steady state, were determined for CM200 material at 1300{degrees}C, 36 kpsi, 190 hr to be 0.0006%/hr and at 1300{degrees}C, 50 kpsi, 190 hr to be 0.0014%/hr. As sintered 3-sigma dimensional tolerances for the vane seat platforms were less than + 0.20 mm, within the component specification tolerance of {plus_minus}0.30 mm. Components have been delivered to GM-Allison for evaluation and test. 2 refs.

Cleveland Tool and Machine (CTM) of Cleveland, Ohio in conjunction with Harrington Product Development Center (HPDC) of Cincinnati, Ohio have developed an advanced, dimensionally accurate, temperature-stable, energy-efficient and cost-effective material and process to manufacture patterns for the investment casting industry. In the proposed technology, FOPAT (aFOam PATtern material) has been developed which is especially compatible with the investment casting process and offers the following advantages: increased dimensional accuracy; increased temperature stability; lower cost per pattern; less energy consumption per pattern; decreased cost of pattern making equipment; decreased tooling cost; increased casting yield. The present method for investment casting is "the lost wax" process, which is exactly that, the use of wax as a pattern material, which is then melted out or "lost" from the ceramic shell. The molten metal is then poured into the ceramic shell to produce a metal casting. This process goes back thousands of years and while there have been improvements in the wax and processing technology, the material is basically the same, wax. The proposed technology is based upon an established industrial process of "Reaction Injection Molding" (RIM) where two components react when mixed and then "molded" to form a part. The proposed technology has been modified and improved with the needs of investment casting in mind. A proprietary mix of components has been formulated which react and expand to form a foam-like product. The result is an investment casting pattern with smooth surface finish and excellent dimensional predictability along with the other key benefits listed above.

An investigation was carried out to study the heat-transfer phenomena across mold flux film by using infrared emitter technique (IET). With IET, it is possible to develop the mold fluxes with a liquid layer at the top and a solid layer in contact with copper mold with the degree of varying crystallization. The dynamic crystallization and melting process of the mold fluxes as well as their effects on the overall heat-transfer rate in the mold were successfully conducted. The single hot thermocouple technique (SHTT) was also employed in this investigation to study the melting and crystallization behaviors of mold fluxes for the interpretation of IET results. The results suggested that the interfacial thermal resistance between the solidified mold flux and copper mold would significantly influence the heat-transfer rate in continuous casting and the melting of the mold flux tends to enhance the overall heat-transfer rate. The technique established in this article by utilizing the IET can be well applied to the investigation of mold flux thermal properties, which in turn gives guidelines for the design of new mold flux for continuous casting.

Poly(phenylene ether) (PPE) is a high temperature polymer (Tg=210°C). Neat PPE is hardly melt-processed below its thermal decomposition temperature. It is believed that the melt-processability is only achieved by blending with polystyrene as a polymeric plasticizer. The polymeric plasticizer sacrifices the heat resistance; the Tg decreases almost linearly with polystyrene content. We found that PPE can react with poly(ethylene-co-glycidylmethacrylate) (EGMA) by melt mixing. Reactive blending of PPE with EGMA yielded an excellent engineering plastic with nice melt-processability, even when a small amount of EGMA (e.g., 5 wt%) was incorporated. The injection molded parts showed high impact strength, high temperature resistance, high tensile strength, and low dielectric loss. It can be classified as a super-engineering plastics. The computer simulation based on a particle-slip model revealed why the melt-processability is attained by the incorporation of polyolefin in pure PPE matrix.   

For the last ten years, the application of high-technology processes to dental ceramics allowed for the development of new materials such as heat-pressed, injection-molded, and slip-cast ceramics and glass-ceramics. The purpose of the present paper is to review advances in new materials and processes available for making all-ceramic dental restorations. Concepts on the structure and strengthening mechanisms of dental ceramics are provided. Major developments in materials for all-ceramic restorations are addressed. These advances include improved processing techniques and greater mechanical properties. An overview of the processing techniques available for all-ceramic materials is given, including sintering, casting, machining, slip-casting, and heat-pressing. The most recent ceramic materials are reviewed with respect to their principal crystalline phases, including leucite, alumina, forsterite, zirconia, mica, hydroxyapatite, lithium disilicate, sanidine, and spinel. Finally, a summary of flexural strength data available for all-ceramic materials is included. PMID:8875028

Abstract in spanish Se ha empleado C-MOLD (herramienta CAE, Asistencia Computacional a Ingeniería) para simular el proceso de inyección de lentes bicóncavas y se ha encontrado que para ciertas geometrías los valores de las variables del proceso de inyección comienzan a ser excesivamente altos. Se han diseñado lentes de 50 mm de diámetro y muy diferentes curvaturas y se ha establecido una relación entre los parámetros geométricos (espesor y curvatura) y las variables de proceso (pre (more) sión máxima de inyección y diferencias de temperaturas al final de la inyección). De las representaciones de las variables de proceso frente a los parámetros geométricos se han podido determinar los valores críticos de los mismos, siendo de 2,2 mm para el espesor en el borde de la lente, 0,75 mm para la ságita, 420 mm para el radio de curvatura y 0,4 mm para el espesor en el centro de la lente. Abstract in english C-MOLD software (CAE tools, Computational Assistant Engineering) has been used to simulate the injection process of biconcave lenses. It has been found that for a given geometry the variables that control de process attain values that are excessively high. Lenses of 50 mm in diameter and very different thickness have been designed and a relationship between the geometrical parameters (thickness and curvature) and the process variables (maximum injection pressure and tempe (more) rature difference at the end of injection) has been established. From the plots of the process variables against the geometrical parameters it has been possible to obtain the critical values of the geometrical parameters: 2,2 mm for the edge thickness, 0.75 mm for sagitta, 420 mm for the curvature radius and 0,4 mm for the thickness at the center of the lens.

We investigated the occurrence of cutaneous depigmentation (vitiligo) among employees of a company that manufactured hydraulic pumps. The interiors of these pumps were injection-molded with rubber. We identified a small but significant cluster of vitiligo cases among a group of employees who frequently handled the rubber used in this injection molding process. Although none of the additives specified in the rubber formulations was a phenolic or catecholic derivative, known to be potential causes of chemically induced vitiligo, gas chromatographic analysis identified a para-substituted phenol (2,4-di-tert-butylphenol, DTBP) in solid samples of the most frequently used rubber. Surface wipe analysis confirmed that workers could be exposed to DTBP from simple handling of the rubber. We subsequently established that the solid bulk rubber used as the base in these stock rubber formulations contained both DTBP and smaller quantities of p-tert-butylphenol. Both had formed as unsuspected byproducts during chemical synthesis of two antioxidants added to the solid bulk rubber by a major rubber supplier. We conclude that the unsuspected presence of potential chemical depigmenting agents in solid bulk rubber, from which industrial rubber products are formulated, may contribute to the occurrence of occupational vitiligo, and that a simple review of ingredients in rubber formulations is inadequate to detect their presence.

In order to develop a mold oscillation-less continuous casting process, i.e. to replace the mold oscillation by an intermittent alternating magnetic field in a continuous caster, a model experimental work has been conducted using molten tin and gallium with low melting point, densities of which are as large as molten steel. The behavior of the mold flux penetrating into a flux channel between the molten metal and the mold and the process forming oscillation marks due to the mold oscillation were visualized. It was found that mold flux can penetrate periodically under the imposition of the intermittent alternating magnetic field even if without mold oscillation. The measured penetration depth of the mold flux agrees well with model predictions. Finally, the molten tin was continuously cast in a cold crucible type copper mold under the imposition of an intermittent alternating magnetic field instead of mold oscillation. It is noticed that molten tin can be successfully cast with the imposition of the magnetic field, but cannot without it. (author)

We tested and characterized molecular coating of Aluminium and Nickel prototype molds and mold inserts for polymer replication via injection molding (IM). X-Ray photoelectron spectroscopy (XPS) data, sessile drop contact angles with multiple fluids, surface energy and roughness data have been collected and used to predict coating lifetimes. Samples have been characterized immediately after coating, after 500+ IM cycles to test durability and after 7 months to test temporal stability. Sessile drop contact angle was measured for multiple fluids, namely water, di-iodomethane and benzylacohol. Detectable coating presence was indicated by an increased angle on all post IM samples. To conclude, we present mold coating evaluation method, which is well suited for ultrathin, controlable, covalently bonded coating, that is reasonably durable, affordable, scalable to production, detectable on surface and especially suitable for rapid prototyping and mold geometry testing.

Induction heating in injection molding has the advantages of rapid heating, reduced cycle time, and improved product quality. In this research, using both experiment and simulation, externally wrapped coil induction heating was applied to verify the heating capacity of a pair of mold plates. By applying different coil designs and mold gap, the effect of the externally wrapped coil induction heating was evaluated. Results showed that when a serial coil was used as an inductor, the heating rate reached 8.0^oC/s. From an initial mold temperature of 40^oC, after 15s heating, the mold surface temperature reached 159.9^oC with the serial coil. The parallel coil shows a better heating uniformity but its heating rate is far lower than the serial coil. For the serial coil, the temperature distribut...

The continuous process of production of molded metallurgical coke from poorly-caking and gas coal types, developed in the USSR, involves thermal treatment of the molded coal in vertical continuous coking ovens. The process of heat transfer is complicated by the movement of the coked material and the requirement of a certain heating rate to the final temperature for strong molded coke. Equations are developed for the calculation of the capacity for molded coke from one running meter of vertical continuous oven with external heating, depending on the oven width and the velocity of the coking material. 8 references, 1 table.

AS-4/polyimidesulfone (PISO2) composite prepreg was utilized for the improved compression molding technology investigation. This improved technique employed molding stops which advantageously facilitate the escape of volatile by-products during the B-stage curing step, and effectively minimize the neutralization of the consolidating pressure by intimate interply fiber-fiber contact within the laminate in the subsequent molding cycle. Without the modifying the resin matrix properties, composite panels with both unidirectional and angled plies with outstanding C-scans and mechanical properties were successfully molded using moderate molding conditions, i.e., 660 F and 500 psi, using this technique. The size of the panels molded were up to 6.00 x 6.00 x 0.07 in. A consolidation theory was proposed for the understanding and advancement of the processing science. Processing parameters such as vacuum, pressure cycle design, prepreg quality, etc. were explored.

Injection molding is the most widely used process in the plastic industry. In the case of semi-crystalline polymer, crystallization kinetics impacts directly the quality of the piece, both on dimensional and mechanical aspects. The characterization of these kinetics is therefore of primary importance to model the process, in particular during the cooling phase. To be representative, this characterization must be carried out under conditions as close as possible to those encountered in the process: high pressure, high cooling rate, shearing, and potential presence of fibers. However, conventional apparatus such as the differential scanning calorimeter do not allow to reach these conditions. A PVT? apparatus, initially developed in the laboratory for the characterization of thermoset composites, was adapted to identify the crystallization kinetics. The aim of the presented study is to demonstrate the feasibility of the identification. This device allows the molding of a circular sample of 40 mm diameter and 6 mm thick by controlling the applied pressure on the sample and the temperature field on its surfaces. This mold is designed such as heat transfer is 1D within the thickness of the sample. It is equipped with two heat flux sensors to determine the average crystallization rate through the thickness and a displacement sensor for the determination of the volume change. The heat transfer problem between the polymer and the molding cavity is modeled by using a 1D conduction problem with a moving boundary, in which the control volume is a uniform temperature disk with a variable volume, and coupled to a crystallization kinetic model. An inverse method is used to identify the parameters of the crystallization kinetic model by minimizing an objective function based on the difference between the evolutions of the experimental and computed volume of the sample. The first validation of this methodology was to compare the kinetic parameters identified with this apparatus with those obtained from DSC experiments, i.e. without additional pressure and at low cooling rates. A good agreement was obtained between both methods. A second validation was to compare experimental and computed temperatures at the center of the plastic part. In this case also, a very good agreement was found. The feasibility of the methodology is now demonstrated. The device is being adapted to increase the level of applied pressure as well as the cooling rate to achieve injection conditions.

Manufacturing of complex-shaped bimetals utilizing two-color powder injection molding (2C-PIM) and three-dimensional printing (3DP) processes, which basically involve sintering of a powder/binder mixture, has been attracted a great interest. This article addresses sintering of biocompatible Co-Cr-Mo alloy for manufacturing stepwise porosity-graded composite structures. Such composite structures provide strength at the core and a porous layer for the tissue growth. To evaluate the process, two grades of gas atomized Co-Cr-Mo powder with an average particle size of 19 and 63mm were used. Isothermal and non-isothermal sintering behavior of the loose powders under hydrogen and argon atmospheres, which is a simulated condition of 2C-PIM and 3DP processes after de-binding, was studied. Microstru...

Developing a rapid and efficient method for removing polymers (termed binders) from a shaped powder component, know as a green body, is important to forming defect-free metal, ceramic, and cermet structures. The rapid growth in powder injection molding to form complex shapes at high precision in large quantities has increased the need for faster, cleaner, and cheaper polymer removal processes. Binder removal using controlled heating of the component in gaseous atmosphere is the most popular method. This thermal debinding or burnout process is a delicate process, since it is easy to crack, blister, slump, or otherwise damage the component with an improperly designed cycle. To avoid these issues, often long heating cycles are used to remove the binder, but with a loss of productivity. Consid...

This study concerns determination of optimum sintering and thermal process parameters for Ni-based alloy 625 superalloy formed by the method of powder injection molding (PIM). Samples, formed from the feedstock by mixing the prealloyed 625 powder with a multi-component binding system, are made subject to sintering at different temperatures following the debinding process. Samples that are sintered under such conditions giving way to the highest relative density (3h at 1300degreeC), are aged after they have been subject to solution treated thermal process. Sintered, solution treated and aged samples have been subjected to microstructural analysis and mechanical test. Mechanical tests such as hardness measurement and tensile test as well as microstructural characterization such as X-ray diff...

A joint project is ongoing to evaluate nondestructive characterization (NDC) methods to detect and measure process-induced variations in ceramic materials. The process methods of current focus are slip-casting and injection molding, and a primary NDC method being evaluated is microfocus X-ray computed tomography (XCT). SiC-whisker-reinforced Si3N4 was pressure-slip-cast under the following conditions: at two casting pressures, 0.103 and 0.276 MPa (15 and 40 psi); and at length/diameter ratios of 1.5, and 2.67 with whisker contents of 20, 23, 27, and 30 wt. percent. Three-dimensional microfocus XCT was used to study density variations in billets produced by different process conditions. Destructive measurement of density variation has been compared to the XCT measurements and correlations have been established. XCT has been proven (by destructive verification) to be capable of detecting less than 5 percent variations in as-cast density.

A joint project is ongoing to evaluate nondestructive characterization (NDC) methods to detect and measure process-induced variations in ceramic materials. The process methods of current focus are slip-casting and injection molding, and a primary NDC method being evaluated is microfocus X-ray computed tomography (XCT). SiC-whisker-reinforced Si[sub 3]N[sub 4] has been pressure-slip-cast at two casting pressures, 0.103 and 0.276 MPa (15 and 40 psi); and at length/diameter ratios of 1.5, and 2.67 with whisker contents of 20, 23, 27, and 30 wt.%. Three-dimensional microfocus XCT has been used to study density variations in billets produced by different process conditions. Destructive measurement of density variation has been compared to the XCT measurements and correlations have been established. XCT has been proven (by destructive verification) to be capable of detecting cast density.

The reduced pressure frozen mold casting process has been known as a recycling-based casting method with several advantages, such as improvement of the work environment, reduction of industrial waste and significant improvement of product yield. In this method, only water and silica sand were used to make mold, which was rapidly frozen at ?40°C, then molten metal was poured into it. In the present investigation, samples were made by the reduced pressure frozen mold casting process and previous processes, and comparisons of their mechanical properties, especially the fatigue strength, were reported.As a result, it was clarified that cast iron made by the reduced pressure frozen mold casting process has a sufficient strength; therefore the reduced pressure frozen mold casting process was expected to be applicable to other castings that have made by previous casting processes.   

Polystyrene (PS), a standard material for cell culture consumable labware, was molded into microstructures with high fidelity of replication by an elastomeric polydimethylsiloxane (PDMS) mold. The process was a simple, benchtop method based on soft lithography using readily available materials. The key to successful replica molding by this simple procedure relies on the use of a solvent, for example, gamma-butyrolactone, which dissolves PS without swelling the PDMS mold. PS solution was added to the PDMS mold, and evaporation of solvent was accomplished by baking the mold on a hotplate. Microstructures with feature sizes as small as 3 µm and aspect ratios as large as 7 were readily molded. Prototypes of microfluidic chips made from PS were prepared by thermal bonding of a microchannel molded in PS with a flat PS substrate. The PS microfluidic chip displayed much lower adsorption and absorption of hydrophobic molecules (e.g. rhodamine B) compared to a comparable chip created from PDMS. The molded PS surface exhibited stable surface properties after plasma oxidation as assessed by contact angle measurement. The molded, oxidized PS surface remained an excellent surface for cell culture based on cell adhesion and proliferation. The micromolded PS possessed properties that were ideal for biological and bioanalytical needs, thus making it an alternative material to PDMS and suitable for building lab-on-a-chip devices by soft lithography methods. PMID:16616608

A greatly simplified method for fabricating poly(methyl methacrylate) (PMMA) separation microchips is introduced. The new protocol relies on UV-initiated polymerization of the monomer solution in an open mold under ambient pressure. Silicon microstructures are transferred to the polymer substrate by molding a methyl methacrylate solution in a sandwich (silicon master/Teflon spacer/glass plate) mold. The chips are subsequently assembled by thermal sealing of the channel and cover plates. The new fabrication method obviates the need for specialized replication equipment and reduces the complexity of prototyping and manufacturing. Variables of the fabrication process were assessed and optimized. The new method compares favorably with common fabrication techniques, yielding high-quality devices with well-defined channel and injection-cross structures, and highly smoothed surfaces. Nearly 100 PMMA chips were replicated using a single silicon master, with high chip-to-chip reproducibility (relative standard deviations of 1.5 and 4.7% for the widths and depths of the replicated channels, respectively). The relatively high EOF value of the new chips (2.12 x 10(-4) cm(2) x V(-1) x s(-1)) indicates that the UV polymerization process increases the surface charge and hence enhances the fluidic transport. The attractive performance of the new CE microchips has been demonstrated in connection with end-column amperometric and contactless-conductivity detection schemes. While the new approach is demonstrated in connection with PMMA microchips, it could be applied to other materials that undergo light-initiated polymerization. The new approach brings significant simplification of the process of fabricating PMMA devices and should lead to a widespread low-cost production of high-quality separation microchips. PMID:15080740

Molecular dynamics simulations are performed to investigate the mold geometry effect on the pattern transfer in thermal nano imprint lithography (NIL). Layered structures composed of single crystalline diamond molds with different taper angles of 0, 15, 30, and 45°, an amorphous poly(methyl methacrylate) (PMMA) thin film, and a rigid silicon substrate were investigated, and the sequential movement of the mold followed by NVT (isothermal ensemble) simulation was implemented in accordance with a real NIL process. Both van der Waals interaction and electrostatic potentials were considered in all non-bond interactions between each layer. From the relative atomic concentration profile of the PMMA resist, the springback effects of the different mold geometries were compared. As a result, mold-PMMA interaction energy, the potential energy variation of the PMMA resist and lateral springback length were determined to be affected by the mold geometry.   

The results of preliminary work on the modeling and measurement of the heat transfer coefficients of metal/mold interfaces is reported. The system investigated is the casting of uranium in graphite molds. The motivation for the work is primarily to improve the accuracy of process modeling of prototype mold designs at the Los Alamos Foundry. The evolution in design of a suitable mold for unidirectional solidification is described, illustrating the value of simulating mold designs prior to use. Experiment indicated a heat transfer coefficient of 2 kW/mS/K both with and without superheat. It was possible to distinguish between solidification due to the mold and that due to radiative heat loss. This permitted an experimental estimate of the emissivity, epsilon = 0.2, of the solidified metal.

U casting was studied using a combined experimental and modeling approach; the U is cast into graphite molds using vacuum induction melting. Mold design and process parameters were varied. FLOW-3D and ABAQUS codes were used. Temperature predictions were compared with experimental data from thermcouples in the mold; initial metal and mold temperatures were used in input to FLOW-3D. Fluid flow predictions were validated using static and dynamic radiographic data. Dynamic radiographic videos of gold castings were compared to 3D simulations.

Abstract In this article, the microstructure and the adhesion developed in co-injected specimens obtained with polypropylene (PP; core) and polystyrene (PS; skin) were studied as a function of process conditions and additives used. The study shows that the incorporation of low amounts of fillers such as Nanoclays and styrene-ethylene-butadiene-styrene (SEBS) copolymer to the core material, working as compatibilizers, improves the adhesion at lower and higher polymer melt temperatures, respectively. The authors concluded as well that the use of such fillers, also improves the reproducibility of the process. The adhesion was assessed by shear tests using double lap shear specimens. A data acquisition system was attached to the mold to evaluate the pressure inside the cavity. Results of the i...

The debinding process in the case of metal injection molding for fabrication of the Fe–6Ni–4Cu compact and variables such as temperature and time has been studied. The debinding process of multiple organic binders in the Fe–6Ni–4Cu compact was investigated by thermal gravimetric analysis (TGA) weight loss and mercury porosimetry analysis. The weight loss of wax and SA dramatically increases from below 10 wt% to 76.0 wt% and 86.0 wt% after immersion in 35°C and 40°C n-hexane for 6 h, respectively. The interdiffusion coefficients of the binder and solvent are 9.763× 10-7 cm2/s and 1.295× 10-6 cm2/s, respectively. The temperature dependent interdiffusion coefficient for the Fe–6Ni–4Cu compact can be expressed as Dx=4.534× 10exp(-5437.2/T). The distribution of pore size is about 0.1–1.9 ?m for the Fe–6Ni–4Cu compact.   

Abstract Recyclability of the bioplastic polyhydroxybutyrate-co-valerate (PHBV) was studied with multiple melt processing (five cycles), with their performances evaluated. A batch of PHBV was processed with a twin screw extrusion followed by injection molding. This operation was repeated five times and samples were collected from each cycle for characterization. For each cycle, the mechanical properties were characterized with tensile, flexural, and impact testing, along with dynamic mechanical analysis. The results showed that the mechanical properties are maintained for four cycles; but in the fifth cycle, there was slight decrease in the properties. Gel permeation chromatography studies revealed that the molecular weight of the polymer does not decrease drastically; however, a drop was ...

This article addresses the processing and ageing properties of jute fiber reinforced polypropylene (PP) composites. The composite has been manufactured by a continuous extrusion process and results in free flowing composite granules, comprising up to 50 weight percent (wt %) jute fiber in PP. These granules have similar shape and diameter as commercially available PP granules. Rheological analysis shows that viscosity of the compounds follows the same shear rate dependency as PP and is on the same level as glass-PP compounds. The mechanical properties show very little variation and exhibit strength and stiffness values at the upper range of competing natural fiber reinforced compounds for injection molding. The mechanical performance reduces gradually upon prolonged thermal loading and imm...

This Cooperative Research and Development Agreement (CRADA) was undertaken to assess the applicability the gelcasting process for forming ceramic green bodies using Saint-Gobain/Norton Industrial Ceramics Corporation`s proprietary CRYSTAR{reg_sign} silicon carbide powder. A gelcasting process, specifically tailored to Saint-Gobain/Norton`s powder composition, was developed and used successfully to form green bodies for property evaluation. This preliminary evaluation showed that the gelcast material had characteristics and properties comparable to Norton`s baseline material. Wafer carrier molds were received from Norton for gelcasting a complex-shaped configuration with CRYSTAR{reg_sign} silicon carbide. Gelcasting experiments showed that Norton`s standard plaster of paris molds were incompatible with the gelcasting process. Mold surface treatments and the use of alternative castable mold materials were investigated, however, a successful process was not identified. The highest quality parts were cast in either glass or aluminum molds.

Layered compaction manufacturing (LCM), which is a hybrid process of powder compaction and milling in layers, is applied to the fabrication of a cemented carbide mold (WC–9 mass%Co) for the forming of optical glass lenses with internal cooling channels, which are placed along the molding cavity. The mold is produced by repeating the process of powder compaction with the subsequent creation of grooves filled with paraffin wax as a sacrificial material. The channels placed along the molding cavity are formed during the sintering process by dewaxing. In the sintering process, the extent of deformation in the shape of the internal channels and molding cavity is measured. It is found that the shapes of the channels and cavity exhibit uniform linear shrinkage in the range from 17 to 19%. By filling the molding cavity with epoxy resin, the cooling capability of the mold by air is investigated by performing experiments as well as two-dimensional finite differences simulation. The cooling effect of the mold in the glass lens-forming process is also estimated by the simulation. For both resin and glass, when air is supplied to the channels, the obtained cooling rate is approximately ten times higher as compared to natural cooling at an ambient temperature.   

Abstract in english The use of high-strength aluminium alloys as material for injection molding tools to produce small and medium batches of plastic products as well as prototyping molds is becoming of increasing demand by the tooling industry. These alloys are replacing the traditional use of steel in the cases above because they offer many advantages such as very high thermal conductivity associated with good corrosion and wear resistance presenting good machinability in milling and electr (more) ical discharge machining operations. Unfortunately there is little technological knowledge on the Electrical Discharge Machining (EDM) of high-strength aluminium alloys, especially about the AMP 8000 alloy. The duty factor, which means the ratio between pulse duration and pulse cycle time exerts an important role on the performance of EDM. This work has carried out an experimental study on the variation of the duty factor in order to analyze its influence on material removal rate and volumetric relative wear under roughing conditions of EDM process. The results showed that high values of duty factor are possible to be applied without bringing instability into the EDM process and with improvement of material removal rate and volumetric relative wear.

Ceramic matrix composites using either continuous ceramic fibers or ceramic whiskers have been shown to have significantly higher fracture toughness than monolithic ceramics. High fracture toughness is necessary for ceramic applications in many advanced heat engines. Nondestructive characterization methods to measure different properties therefore are important for both types of materials. Mass production methods such as slip casting and injection molding, for composites or monolithics, require high reliability; thus, the development of nondestructive characterization methods for process control can have a high payoff. A method of producing continuous-fiber composites is by chemical vapor infiltration (CVI). In this technology, production and process development requires knowledge of the as-infiltrated density distribution and the orientation of the fibers after infiltration. We have demonstrated on injection-molded Si{sub 3}N{sub 4} with 10--15 wt.% binder that by appropriate use of high-gradient-field nuclear magnetic resonance (NMR) imaging and microfocus 3-D X-ray computed tomography (CT), the distribution of polymeric binders can be mapped to with {plus minus}0.5 wt.%. In the case of SiC/SiC CVI continuous-fiber composites made with 0,+, {minus}30 degree cloth layups, we have shown that density variations attributed to process conditions can be detected and that fiber orientations can be determined to better than {plus minus}2 degrees by 3-D X-ray microfocus CT data, together with advanced image processing. All data were acquired on NMR and X-ray CT machines designed and built at Argonne National Laboratory. 15 refs., 7 figs., 5 tabs.

Abstract in spanish Se ha realizado un estudio comparativo entre las deformaciones reales de una pieza industrial obtenida por inyección y los desplazamientos obtenidos por simulación empleando C-MOLD, con el objeto de verificar la utilidad predictiva de herramientas de simulación de procesos. La pieza seleccionada es un aforador, fabricado en poliamida 6/10 con un 50% de fibra corta de vidrio, que presenta suaves rechupes en las zonas laterales como principal defecto. La simulación del (more) proceso se realizó con las condiciones empleadas por el fabricante y, posteriormente, se optimizó para máquinas de inyección Engel 125 y 175. Con los parámetros óptimos de proceso se fabricaron piezas y se midieron las deformaciones en puntos situados en dos ejes paralelos a la dirección longitudinal de la pieza. Estas deformaciones se compararon con los valores de desplazamiento obtenidos por simulación encontrándose una coincidencia excelente entre ambos, excepto en las zonas próximas a los extremos de la pieza. Abstract in english A comparative study between the actual deformation of a real industrial part obtained by injection moulding and the displacement in the same simulated part has been performed using C-MOLD, with the objective of verifying the predictive capabilities of process simulation tools. The selected part is a gauge, made of polyamide 6/10 reinforced with 50% of fibber glass, that presents soft sink marks in the lateral areas as main defects. Process simulation was initially perform (more) ed using the process conditions used by the manufacturer and, in a later stage, those conditions were optimised for Engel 125 and 175 injection machines. Using the optimum process parameters a set of parts was manufactured and the deformations were measured in several points located along two parallel longitudinal axis. These deformations were compared with displacement values obtained from simulation. Excellent agreement between the two sets of values was found except in the most external regions of the part.

A new method of fabricating translucent alumina brackets using powder injection molding (PIM) is reported. Alumina powder was mixed with MgO, La2O3, and Y2O3 to control grain size and porosity. The powders were mixed with a binder consisting of a mixture of paraffin wax and polyethylene in a 1:1 ratio to make feedstock for injection molding. The total amount of binder was limited to 14 wt% to minimize shrinkage and cracking after sintering. After injection molding, debinding was performed using the wicking method and samples were sintered in a vacuum at 1700 °C to achieve high density. Ultimately, translucent corundum was fabricated. The sintering additives resulted in a decrease in porosity and an improvement in translucency by promoting grain growth during pressure-less sintering. After ...

A load-cell-embedded burnishing tool has been newly developed and integrated with a machining center, to improve the surface roughness of the PDS5 plastic injection mold steel. Either the rolling-contact type or the sliding-contact type was possible for the developed ball burnishing tool. The characteristic curves of burnishing force vs. surface roughness for the PDS5 plastic injection mold steel using the developed burnishing tool for both the rolling-contact type and the sliding-contact type, have been investigated and constructed, based on the test results. The optimal plane surface burnishing force for the PDS5 plastic injection mold steel was about 420N for the rolling-contact type and about 470N for the sliding-contact type, based on the results of experiments. A force compensation s...

We fabricated microlenses and the logo of the National Institute of Advanced Industrial Science and Technology (AIST) on Pyrex glass by employing thermal nanoimprint technology. The mold material used for imprinting on Pyrex glass was an amorphous Ni–P alloy that was deposited on Inconel-600 by electroless plating technology. The complete fabrication technique consisted of highly accurate processing by focused-ion-beam (FIB) on material that involved a high-temperature thermal treatment that has the advantage of improving the hardness of the mold. An amorphous Ni–P alloy layer on an Inconel-600 substrate was characterized by measuring its X-ray diffraction spectrum. Using this technique we successfully developed a low-cost mold for imprinting on Pyrex glass instead of using a more expensive glass-like carbon mold that is commonly used for this purpose. Microlenses with concave curvatures having radii of 12 and 20 ?m were created on the mold by a FIB system equipped with three-dimensional computer-aided-design (CAD) software. This mold was used for thermal imprinting on Pyrex glass substrates to fabricate microlenses and the AIST logo. When polished Inconel-600 was used as a substrate for molds, the accuracy of the Ni–P mold proved to be of higher quality than a mold made of unpolished Inconel-600. The microlenses made using Ni–P/polished-Inconel-600 molds showed lubricious surfaces that were not possible to achieve using Ni–P/unpolished-Inconel-600 molds. Moreover, some of the parameters in Ni–P electroless plating were changed in order to make three kinds of molds with P content ratios of 4, 8, and 16 wt %. The micro-vickers hardness caused by thermal treatment and the differences among the transcript values on Pyrex glass were also evaluated experimentally.   

Nano-/micro-scale structures of transparent crosslinked polytetrafluoroethylene (RX-PTFE) mold have been fabricated by combined process which is thermal and radiation process for fabrication of RX-PTFE (TRaf process). The nano-/micro-fabricated RX-PTFE were attempted to be applied for the transparent polymer molds of UV nanoimprint lithography (NIL). The ability of the RX-PTFE mold for UV-NIL was evaluated by the imprinted patterns. The RX-PTFE molds and the imprinted structures obtained by UV-NIL were observed by a field emission scanning electron microscope (FE-SEM). As a result, imprinted structures of photo-curable resin (Trimethylolpropane-triacrylate: TMPTA) by UV-NIL using RX-PTFE mold were successfully obtained. The nano-scale L&S patterns, square (410 nm × 410 nm) and hole (? 170 nm) array patterns were clearly obtained.   

Because of the limitation of manufacturing capability, free-form glass optics cannot be produced in a large volume using traditional processes such as grinding, lapping, and polishing. Very recently compression molding of glass optics became a viable manufacturing process for the high-volume production of precision glass optical components. An ultraprecision diamond-turning machine retrofitted with a fast tool servo was used to fabricate a free-form optical mold on a nickel-plated surface. A nonuniform rational B-spline trajectory generator was developed to calculate the computer numerical control machine tool path. A specially formulated glass with low transition temperature (Tg) was used, since the nickel alloy mold cannot withstand the high temperatures required for regular optical glasses. We describe the details of this process, from optical surface geometry, mold making, molding experiment, to lens measurement. PMID:16912790

An experimental apparatus to determine the heat-transfer coefficient in the gap formed between the cast metal and the mold wall of a vertical direct chill (DC) casting mold is described. The apparatus simulates the conditions existing within the confines of the DC casting mold and measures the heat flux within the gap. Measurements were made under steady-state conditions, simulating the steady-state regime of the DC casting process. A range of casting parameters that may affect the heat transfer was tested using this apparatus. In the current article, the operation of the apparatus is described along with the results for the effect of gas type within the mold, and the size of the metal-mold gap formed during casting. The results show that the gas type and the gap size significantly affect the heat transfer within a DC casting mold. The measured heat fluxes for all the conditions tested were expressed as a linear correlation between the heat-transfer coefficient and the metal-mold gap size, and the fluxes can be used to estimate the heat transfer between the metal and the mold at any gap size. These results are compared to values reported in the literature and recommendations are made for the future reporting of the metal/mold heat-transfer coefficient for DC casting. The results for the effect of the other parameters tested are described in Part II of the article.

Experimental and analytical studies toward the goal of replacing the fiberglass reentrant support posts and their end restraint systems with lower cost injection molded posts are described. Thermoplastic resins with chopped fiberglass reinforcement having lower thermal conductivity were investigated. Experimentally obtained data from creep, shear, and tensile tests on actual injection molded posts of Ultem and Noryl are included. Discussion of flaws and quality control is included. These studies for the Relativistic Heavy Ion Collider (RHIC) and the Superconducting Super Collider (SSC) are continuing at Brookhaven National Laboratory and at the SSC Laboratory. 6 refs., 13 figs.

Weld lines are a major concern to designers since they result in poor mechanical properties. Designers may overdesign parts when considering anticipated failure modes and safety factors by locating weld lines in non-critical areas without taking into account material factors. This study focus on the effect of part thickness on the weld-line strength of injection-molded short-fiber-reinforced thermoplastic composites. Comparisons were made with specimens without weld lines. The use of design data which takes into account fiber orientation and part thickness will enable designers to more accurately predict the performance of an injection-molded thermoplastic composites under applied load.

Various polyarylates from substituted hydroquinones (HQs) and substituted 1,2-bis(phenoxy)ethane-4,4?-dicarboxylic acids (PECs) or 4,4?-diphenyldicarboxylic acid (BB) were prepared. Thermal properties, orientation function of nematic domains (F value) and morphology of fibers and injection molded specimens of them were investigated. From these results, it is assumed that the stability of liquid crystallinity, rigidity of the polymer chain and F value are the important factors determining the modulus of fibers. On the other hand, the stability of liquid crystallinity, rigidity of the polymer chain and packing density of the polymer chain are assumed to be the influential factors to determine the modulus of injection molded specimens.   

An experimental study on heat transfer and flow in compression molding of class-B SMC in flat and T-shape cross-sectioned was carried out. The influences of mold temperatures and mold closing speeds on cure and pressure requirements during the process were examined. Three different mold speed, 15, 45, 50 mm/min and two different mold temperatures, 130{sup o} C and 150{sup o} C are used for compression molding experiments. Experiments with different colored SMC charge were performed to study flow pattern at various compression ratios. Glass fiber orientation in flat plate and cross-sectional T-shape were investigated by SEM. In addition, compression test of cylindrical specimens made of class-A SMC sheet at 20{sup o} C, 50{sup o} C, 75{sup o} C was performed to characterize the material property as a function of temperatures. The study was to establish a relationship between the processing variables and mechanical properties of the molded SMC parts. As a result of this investigation, a reasonable prediction of the properties of a molded component with given processing conditions can be made. (author). 25 refs. 5 tabs. 42 figs.

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