• Transactions of Materials Processing
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• v.16 no.7
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• pp.549-554
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• 2007

The objective of this paper is to investigate into the fabrication technology of cores for the injection mould with three-dimensional conformal cooling channels to reduce the cooling time. The location of the conformal cooling channels has been determined through the injection molding analysis. The mould has been manufactured from a hybrid rapid tooling technology, which is combined a direct metal rapid tooling with a machining process. Several injection molding experiments have been performed to examine the productivity and the validity of the designed mould. From the results of the experiments, it has been shown that the proposed mould can mold a final product within a cooling time of 3 seconds and a cycle time of 21 seconds, respectively.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.02a
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• pp.187-194
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• 2002

This paper describes the experimental results on direct selective laser sintering of WC-Co mixture for rapid tooling. The experiments were carried out within an air, argon and nitrogen atmosphere. Coupons of single layer were sintered at various laser powers, scanning speeds and scan spacings. As the energy density (energy per unit scanned area) is increased, the thickness of coupons is increased. The main problem took place during sintering within an air atmosphere was severe oxidation of WC-Co mixture. As the laser power is increased and/or scanning speed is decreased, more severe oxidation occurred. Within an argon and nitrogen atmosphere the oxidation is reduced significantly. Experiments on multi-layer sintering were also carried out.

• CDE review
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• v.8 no.2
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• pp.47-52
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• 2002

레이저를 이용한 직접금속성형기술(영문명 : DMT: Direct Metal Tooling)은 고 부가가치의 기능성 소재(금속, 합금, 세라믹 등)의 미세한 분말을 원하는 3차원 공간상에 주사함과 동시에 이를 레이저로 직접, 순간 용착시키며 이것이 공간상에서 축적되가면서 미리 정해진 3차원 파트형상이 자동적으로 빌드업 되도록 하는 고도의 정밀제어 기술을 요하는 신기술이다. 이는 컴퓨터에 저장된 3차원 디지털 형상정보(digital data of 3D subjects)만 갖고 있으면 이로부터 그에 해당하는 금속파트형상을 적절히 소재분말을 이용하여 곧바로 실물로 재현하여 얻을 수 있게 됨을 의미하며 이로서 기존에 절삭기계를 이용한 가공 공법보다 손쉽고 빠르면서도 반면 기계적 성질은 종전기술보다 월등히 우수한 B차원 금속 파트나 금형 형상을 소재의 낭비가 전혀 없는 환경 친화적인 방법으로 제작할 수 있는, 소위 밀레니엄시대를 대표하는 최첨단 미래형 기술의 구현이다.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.11
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• pp.103-108
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• 2019

The cooling rate and the uniformity of mold temperature, in the injection molding process, possess great influences on the productivity and quality of replications. The conformal cooling channel, which is of a uniform spacing from the mold cavity by the metal additive manufacturing process, receives much attention recently. The purpose of this study is to develop a mold core with a curved conformal cooling channel for a pottery-shaped thick-wall cosmetic container through the hybrid method of direct metal tooling (DMT) process. In this study, we design a mold core that contains the curved cooling channel for the container. A method that divides the cavity is proposed and the DMT process is carried out to form the curved cooling channel. The test mold core, with the curved conformal cooling channel, has been fabricated by the proposed method to confirm the feasibility of the design concept. We show that no leakage is observed for the additive manufactured test mold core, and its physical properties demonstrate that it can be sufficiently used as the injection mold core.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.1 s.173
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• pp.1-6
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• 2000

As dies and molds have become more and more complicated in the recent years, the demand for lower cost and shorter production time is also growing stronger. Rapid prototyping and Tooling technologies are expected to be used for more rapid and lower cost tool fabrication. However the rapid tooling methods have not yet reached the level of application to the manufacturing of metallic dies and molds which require high dimensional accuracy. As the rapid tooling technology, there are the slurry casting, the powder casting, the direct laser sintering, and so on. Generally, in the slurry casting, the alumina powder and the water soluble phenol were mainly used. However, the mechanical properties of the phenol were not good enough to apply to molds directly. In this study, pure epoxy and two types of aluminium powder reinforced resin are applied to the slurry casting. The mechanical and thermal properties are better than phenol because the epoxy is the thermosetting resin. And mechanical characteristics such as shrinkage rate, hardness, surface roughness are measured for the sake of comparison. Metal powder reinforced resin molds are better than the resin tool form the viewpoint of shrinkage rate and hardness. Finally, it has been shown that the application possibility of this process is high, because the manufacturing time and cost savings are significant.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.1019-1020
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• 2009

• Journal of the Korean Society for Precision Engineering
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• v.33 no.4
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• pp.279-286
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• 2016

To enhance the safety of nuclear reactors after the Fukushima accident, researchers are developing various types of accident tolerant fuel (ATF) to increase the coping time and reduce the generation of hydrogen by oxidation. Coated cladding, an ATF concept, can be a promising technology in view of its commercialization. We applied 3D printing technology to the fabrication of coated cladding as well as of coated pellets. Direct metal tooling (DMT) in 3D printing technologies can create a coated layer on the tubular cladding surface, which maintains stability during corrosion, creep, and wear in the reactor. A 3D laser coating apparatus was built, and parameter studies were carried out. To coat pellets with erbium using this apparatus, we undertook preliminary experiments involving metal pellets. The adhesion test showed that the coated layer can be maintained at near fracture strength.

• Korean Journal of Computational Design and Engineering
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• v.8 no.3
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• pp.150-156
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• 2003

Direct Metal Deposition (DMD) is a new additive process producing three-dimensional metal components or tools directly from CAD data, which aims to take mold making and metalworking in an entirely new direction. It is the blending of five common technologies: lasers, CAD, CAM, sensors and materials. In the resulting process, alternatively called laser cladding, an industrial laser is used to locally heat a spot on a tool-steel work piece or platform, forming a molten pool of metal. A small stream of powdered tool-steel metal is then injected into the metal pool to increase the size of the molten pool. By moving the laser beam back and forth, under CNC control, and tracing out a pattern determined by a computerized CAD design, the solid metal part is eventually built line-by-line, one layer at a time. DMD produces improved material properties in less time and at a lower cost than is possible with traditional fabrication technologies.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.199-200
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• 2006

It will not be an exaggeration to say that one of the most important features of RT (Rapid Tooling) technology is to easy manufacturing complex shape of cooling channel in injection mold. That is, RT technology is hardly influenced complex shape of tool, Therefore, mold designer can optimize the position and shape of cooling channel whatever they want. In this study, we optimized cooling channel through CAE analysis to solve the problem; prototype-connector-mold applied conventional cooling channel, locally warped by internal stress: The effect of three-dimensional cooling channel was supported by simulation result. But it is impossible to produce injection mold applied three-dimensional cooling channel through machining operation. Therefore, we produced the prototype-connector-mold with three-dimensional cooling channel using Direct Metal Laser Sintering (DMLS) process, and get good-quality prototype-connector without warpage.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.3
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• pp.9-14
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• 2015

The Direct Metal Tooling (DMT) process is a kind of additive manufacturing processes, which is developed using various commercial steel powders, such as P20, P21, SUS420, and other non-ferrous metal powders. The DMT process is a versatile process that can be applied to various fields, such as the molding industry, the medical industry, and the defense industry. Among them, the application of the DMT process to the molding industry is one of its most attractive and practical applications, since the conformal cooling channel cores of injection molds can be fabricated at a slightly expensive cost by using the hybrid fabrication method of DMT technology compared with parts fabricated with machining technology. The main objectives of this study are to provide various characteristics of the parts made using the DMT process compared with the same parts machined from bulk materials and evaluate the performance of the injection mold equipped with a conformal cooling channel core fabricated using the hybrid method of the DMT process.