• Design & Manufacturing
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• 제8권1호
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• pp.27-30
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• 2014

Alloy tool steel such as SKD11 and SKD61 or high speed tool like SKH51 are used as materials for semiconductor dies. Cavities, curl blocks, pot blocks and housings are made from those materials. To make those parts from alloy tool steel or high speed tool, one utilizes discharge machining, and mechanical machining including machining center, milling, drilling, forming grinding and others. In the process of cutting machining and polishing, the die materials become unsuitable for machining owing to bubbles and foreign substances in them, which hinders production process. Therefore, this study focuses on die material selection criteria, and on analysis and comparison of material characteristics to help companies to solve their problems, make die manufacture less burdensome and extend die life.

• 한국안전학회지
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• 제13권1호
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• pp.19-25
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• 1998

In this study, proper injection molding condition has been studied through stress relaxation tests in order to experimentally investigate the effect of the condition on softening of mold product, using specimens produced under the different conditions according to the recommendation of resin manufactures. As a result, softening of the specimens was found to be strongly influenced by material melting temperature. The specimen with higher material melting temperature is found to have lower softening. However, softening of the specimen with lower mold temperature has an decrement, compared with other specimens. In particular, specimen with notch is influenced by mold temperature. The softening increase with higher injection speed and pressure. Finally in order to improve softening, material melting temperature, injection speed and injection pressure were found to be increased with low mold temperature.

• 한국주조공학회지
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• 제27권1호
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• pp.24-30
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• 2007

The effects of C, Si and RE additions on the tendency of chill formation of ductile cast iron obtained from metal mold casting were investigated. In case of metal mold cast, the ductile cast iron with 2.5%Si had pearlitic matrix, and specimens with 2.9%Si had bull's eye type regardless of C contents. As-cast specimen with a large amount of fine graphites could be obtained by adding 0.2% RE. Normalizing process was necessary to remove carbide and form a large amount of spheroidal graphites for the as-cast specimens. Good mechanical properties could be obtained by heat-treatment of as-cast specimens with pearlitic matrix. Normalizing the specimens with RE caused the reduction in mechanical properties.

• 한국산학기술학회논문지
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• 제13권10호
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• pp.4392-4397
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• 2012

본 연구에서는 우레탄레진(TSR-755)을 이용하여 레이저 조형으로 시작형 몰드를 가공하고, 상용패키지(Unigraphics)를 이용하여 자동차 단자함 케이블 케이스를 설계한 후 사출성형해석(Simpoe-Mold)을 사용하여 충전, 보압, 냉각, 변형해석을 수행하여 게이트 위치 선정 및 냉각 사이클 등을 검토 하였다. 해석결과, 세라믹소재 가공 후 사출금형에 인서트시켜 성형 시 열전도도 및 냉각시간을 줄여 줌을 확인할 수 있으며, 게이트 및 냉각라인 선정을 빠른 시간에 결정할 수 있어 생산성 향상을 가져올 것으로 나타났다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.484-487
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• 2002

The mold transformers have been widely used in underground substations in large building and have some advantages in comparison to oil-transformer, that is low fire risk, excellent environmental compatibility, compact size and high reliability. In addition, the application of mold transformer for outdoor is possible due to development of epoxy resin. The mold transformer generally has cooling duct between low voltage coil and high voltage coil. A mold transformer made by one body molding method has been developed for small size and low loss. In this paper, the proto type mold transformer of 50kVA class is investigated by routine, type, special test. The outdoor energized aging test is investigated by back-to-back method to verify the long time performance of pole mold transformer. The aging process of transformer is analyzed by various diagnosis method such as DC voltage-current test, $tan{\delta}$, Meggar measurement, winding temperature and etc.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.308-311
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• 2002

Removal of gas in a mold has been a big problem in pressing mold or in injection mold. Air vent has been used to solve the problem, but it has weak points such as the Increased cost, the increased number of process. and vent marks on the surface of a product. In this study, the sintering method and rapid tooling method are used for making porous metal mold. Porous metal mold has many open pores, which are very small. When porous metal mold is used for pressing mold or injection mold, all process would be made short, produce cost would be down, and vent marks would be not leaved on the surface of a product. Characteristic of Porous material varies from sintering conditions, which are the length of sintering time, sintering temperature and sintering atmosphere etc. This study will find optimized sintering condition for the porous metal mold.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.111-111
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• 2010

The mold transformers have been widely used in underground substations in large building and have some advantages in comparison to oil-transformer, that is low fire risk, excellent environmental compatibility, compact size and high reliability. In addition, the application of mold transformer for outdoor is possible due to development of epoxy resin. The mold transformer generally has cooling duct between low voltage coil and high voltage coil. A mold transformer made by one body molding method has been developed for small size and low loss, but it needs some cooling method because heat radiation between each winding is difficult. In this paper, the temperature distribution and thermal stress analysis of H class 100kVA pole cast resin transformer for power distribution are investigated by FEM program.

• Design & Manufacturing
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• 제17권3호
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• pp.61-66
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• 2023

In this study, we developed a simulation methodology for a technology that rapidly cools molds by directly spraying them with CO₂ in its liquefied gaseous state. Initially, a simulation verification process was conducted using ANSYS Fluent's heat transfer analysis based on temperature values measured in prior research experiments, ensuring a comparable temperature could be calculated. Subsequently, the validated analysis method was employed to evaluate design factors that exert the most significant influence on cooling. An evaluation was conducted based on three factors: part thickness, mold thickness, and the melting temperature of material. Using a full factorial design approach, a total of 27 analyses were completed and subsequently calculated through analysis of means. The impact assessment was carried out based on the temperature values at the product's core. The results indicated that the thickness of the mold had the highest influence, while the melting temperature of material had the least.

• 한국정밀공학회지
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• 제20권1호
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• pp.91-98
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• 2003

Removal of gas in a mold has been a big problem in pressing mold or in injection mold. Air vent has been used to solve the problem, but it has weak points such as the increased cost, the increased number of process, and vent marks on the surface of a product. In this study, the sintering method and rapid tooling method are used for making porous metal mold. Porous metal mold has many open pores, which are very small. When porous metal mold is used for pressing mold or injection mold, all process would be made short, produce cost would be down, and vent marks would be not leaved on the surface of a product. Characteristic of porous material varies from sintering conditions, which are the length of sintering time, sintering temperature and sintering atmosphere etc. This study will find optimized sintering condition for the porous metal mold.

• 한국분말재료학회지
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• 제18권2호
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• pp.141-148
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• 2011

Carbon material shows relatively high strength at high temperature in vacuum atmosphere and can be easily removed as CO or $CO_2$ gas in oxidation atmosphere. Using these characteristics, we have investigated the applicability of carbon mold for precision casting of high melting point metal such as nickel. Disc shape carbon mold with cylindrical pores was prepared and Ni-base super alloy (CM247LC) was used as casting material. The effects of electroless Nickel plating on wettability and cast parameters such as temperature and pressure on castability were investigated. Furthermore, the proper condition for removal of carbon mold by evaporation in oxidation atmosphere was also examined. The SEM observation of the interface between carbon mold and casting materials (CM247LC), which was infiltrated at temperature up to $1600^{\circ}C$, revealed that there was no particular product at the interface. Carbon mold was effectively eliminated by exposure in oxygen rich atmosphere at $705^{\circ}C$ for 3 hours and oxidation of casting materials was restrained during raising and lowering the temperature by using inert gas. It means that the carbon can be applicable to precision casting as mold material.