• Journal of Powder Materials
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• v.9 no.4
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• pp.267-272
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• 2002

The production of micro components is one of the leading technologies in the fields of information and communiation, medical and biotechnology, and micro sensor and micro actuator system. Microfabrication (micromachining) techniques such as X-ray lithography, electroforming, micromolding and excimer laser ablation are used for the production of micro components out of silicon, polymer and a limited number of pure metals or binary alloys. However, since the first development of microfabrication technologies there have been demands for the cost-effective replication in large scale series as well as the extended range of available material. One such promising process is micro powder injection molding (PIM), which inherits the advantages of the conventional PIM technology, such as low production cost, shape complexity, applicability to many materials, applicability to many materials, and good tolerance. This paper reports on a fundamental investigation of the application of W-Cu powder to micro metal injection molding (MIM), especially in view of achieving a good filling and a safe removal of a micro mold conducted in the experiment. It is absolutely legitimate and meaningful, at the present state of the technique, to continue developing the micro MIM towards production processes for micro components.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.93-94
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• 2006

A novel production method for porous metal components has been developed by applying powder space holder (PSH) method to metal powder injection molding (MIM) process. The PSH-MIM method has an industrial competitive advantage that is capable of net-shape manufacturing the micro-sized porous metal products with complicated shapes and controlled porosity and pore size. In this study, the small impeller with homogeneous micro-porous structure was manufactured by the PSH-MIM method. The effects of combinations in size and fraction of PMMA particle on dimensional tolerance and variation of sintered porous specimens were investigated. It was concluded that the PSH-MIM method could manufacture commercially microporous metal components with high dimensional accuracy.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.43-44
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• 2006

The production method of micro sacrificial plastic mold insert metal injection molding, namely ${\mu}-SPiMIM$ process has been proposed to solve specific problems involving the miniaturization of MIM. Two types of sacrificial plastic molds (SP-mold) with fine structures were used: 1) PMMA resist, 2) PMMA mold injected into Ni-electroform, which is a typical LIGA (${\underline{L}}ithographie-{\underline{G}}alvanoformung-{\underline{A}}bformung$) process. Stainless steel 316L feedstock was injection-molded into the SP-molds with multi-pillar structures. This study focused on the effects of metal particle size and processing conditions on the shrinkage, transcription and surface roughness of sintered parts.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.36-37
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• 2006

This study aims to investigate the usage of nano-scale particles in a micro metal injection molding ($\mu$-MIM) process. Nanoscale particle is effective to improve transcription and surface roughness in small structure. Moreover, the effects of hybrid micro/nano particles, Cu/Cu and SUS/Cu were investigated. Small dumbbell specimens were produced using various feedstocks prepared by changing binder content and fraction of nano-scale Cu particle (0.3 and $0.13{\mu}m$ in particle size). The effects of adding the fraction of nano-scale Cu powder on the melt viscosity of the feedstock, microstructure, density and tensile strength of sintered parts were discussed.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.04a
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• pp.23-23
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• 2006

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.60-63
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• 2009

Manufacturing technologies of micro spur gear and micro mold by micro PIM were studied with stainless steel feedstock. For molding of gears, micro mold with gear cavity of 1.2 mm in diameter was produced by wire EDM. The proper injection pressure was selected to 70bar by observation and measuring of shapes and shrinkage of gears before/after sintering. For fabrication of micro mold, a tiny polymer gear was produced by injection into the mold. Then, 316L feedstock was again injected/compressed on the polymer gear and debinded together with polymer gear followed by sintering. As a result, another metal mold with gear cavity reduced to about 20% was fabricated and through repetition of this process chain, micro gear mold with cavity about below 800 um was finally obtained. In reduction of size by injection/compression molding, height of gear tooth was shrunk more and the effort for decrease of roughness of micro cavity were carried out ultrasonic polishing and as a result, the roughness in cavity decreased from 3-4 um to about 200 nm.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.773-774
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• 2006

Gas surface treatment is considered to be effective for titanium because of its high reactivity. In this study, we investigated the gas nitriding mechanism in titanium sintered parts produced by metal powder injection molding (MIM) process. The microstructure and nitrogen content of sintered MIM parts were greatly affected by nitriding conditions. Nitriding process strongly depended on the specimen size, for example, the size of micro metal injection molding (${\mu}-MIM$) product is so small and the specific surface is so large that the mechanical and functional properties can be modified by nitriding.

• Transactions of Materials Processing
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• v.19 no.3
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• pp.191-196
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• 2010

Tungsten-carbide as typical difficult-to-cut material has excellent mechanical properties such as high thermal resistivity, mechanical strength and chemical durability. However, it is next to impossible for tungsten-carbide to be fabricated the needed parts by cutting process. In this study, for establishing the micro fabrication method of tungsten-carbide for micro injection or compression molding core, the investigation on micro cutting characteristics of tungsten-carbide green part which is made by powder injection molding process and easy to cut relatively was performed. For this, micro endmilling experiments of tungsten-carbide green part were performed according to various cutting conditions. Finally, the wear trend of micro endmill and the appearance of micro rib according to feed-rate and cutting depth per step were analyzed through SEM images of micro cutting feature and microscope images of micro tools.

• Design & Manufacturing
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• v.11 no.3
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• pp.1-7
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• 2017

The fabrication process of micro pattern structure with high precision and high aspect ratio using powder injection molding (PIM) is developed. In the PIM process, the metal powder is mixed with the binder systems and the mixture is injected into the metal mold. The injection molded green parts are debinded and sintered to reach final shape and properties. In this method, the optimization of physical properties such as fluidity and strength of the binder system is essential for perfect filling the high aspect ratio micro-pattern. For this purpose, the correlation between the properties of the binder system and feedstock and ${\mu}-PIM$ process was investigated, and a binder system with low viscosity at low temperature(about $110^{\circ}C$) and high strength after cooling was investigated and applied. Employing this process, high precision parts with line type micro pattern structure which has pattern size $160{\mu}m$ and aspect ratio more than 2 can be manufactured.

• Design & Manufacturing
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• v.14 no.4
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• pp.71-77
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• 2020

Various manufacturing technologies, including over-molding and insert-injection molding, are used to produce hybrid plastics and metals. However, there are disadvantages to these technologies, as they require several steps in manufacturing and are limited to what can be reasonably achieved within the complexities of part geometry. This study aims to determine a practical approach for producing metal/plastic hybrid components by combining plastic injection molding and metal die casting to create a new hybrid metal/plastic molding process. The integrated metal/plastic hybrid injection molding process developed in this study uses the proven method of multi-component technology as a basis to combine plastic injection molding with metal die casting into one integrated process. In this study, the electrical conductivity and ampacity were verified to qualify the new process for the production of parts used in electronic devices. The electrical conductivity was measured, contacting both sides of the test sample with constant pressure, and the resistivity was measured using a micro ohmmeter. Also, the specific conductivity was subsequently calculated from the resistivity and contact surface of the conductor path. The ampacity defines the maximum amount of current a conductive path can carry before sustaining immediate or progressive deterioration. The manufactured hybrid multi-components were loaded with increasing currents, while the temperature was recorded with an infrared camera. To compare the measured infrared images, an electro-thermal simulation was conducted using commercial CAE software to predict the maximum temperature of the power loaded parts. Overall, during the injection molding process, it was demonstrated that multifunctional parts can be produced for electric and electronic applications.