• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.348-349
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• 2006

The plastic deformation behavior of cemented carbides is related to the WC grain boundary strength. Ab initio calculations predict that Co and Mn segregate to WC/WC grain boundaries. To experimentally study the effect of Mn, a WC-Co-Mn material was manufactured and compared to a WC-Co material. The microstructure was studied using scanning electron microscopy (SEM), including electron backscatter diffraction (EBSD). Special attention was paid to the WC grain size and the frequency of special low-energy grain boundaries. Mn was found to have negligible effect on both the WC grain growth and the fraction of $\sum2$ WC/WC boundaries in the as-sintered material.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 금형가공,미세가공,플라스틱가공 공동 심포지엄
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• pp.110-113
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• 2005

In recent, various shapes of pattern in micron or nano scale are adapted in many applications due to their good mechanical or optical properties. Light guide panel (LGP) of the LCD is one of important applications for micro pattern and micro prism shape is one of the typical patterns. Many applications have the patterns on their surface and the size of the pattern keep decreasing down to the order of micron or even under micron. On the other hand, the area to be patterned keeps enlarging. These two trends in patterned products require tooling micro patterns on large surface, which has still many technical problems to be solved mainly due to pattern size and the tooling area. In this study, we fabricate prism shape of patterns using diamond cutting tool on some metal core and plastic core like PMMA Some of cutting conditions are investigated including cutting force, cutting depth and speed for different core materials.

• 한국정밀공학회지
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• 제23권8호
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• pp.203-210
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• 2006

This paper focuses on the development of RT technology suitable for manufacturing a small quantity of metal prototype of a precise part from an RP master. Dimensional accuracy and surface roughness are evaluated from Thermojet part of a 3D printer, and effective post-processing method is introduced. Investment casting is done using a prototype built from 3D printer as a wax pattern. Ceramic shell investment casting technique is developed to build a prototype with materials mostly wanted. Also, experimental result shows this research is very useful in manufacturing of a small quantity of functional part or a test part of a specific material.

• 한국정밀공학회지
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• 제16권11호
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• pp.62-67
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• 1999

The RP&M(Rapid Prototyping and Manufacturing) is the most appropriate technology for the small-lot production system, in which the production cycle is getting shorter owing to various needs from consumers. Recently RP products which are made of plastics, wax, and paper are used to verify the design of samples. But these products cannot be applied to the real mold because the strength enough to be a mold cannot be given by soft materials such as plastics. So RP products are copied to AFR(Al powder Filled Resin) molds or metal molds, which is called the RP&M. In this paper, RP&M is applied to a casting process. A porous casting mold, which is made from ceramic powder and binder, is used for rapid tooling of aluminum shoes molds.

• 한국정밀공학회지
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• 제21권9호
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• pp.196-203
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• 2004

SL(Stereolithography) part is made by piling up thin layers which causes the stair stepping effect at the surface of SL parts. The effect brings about excessive surface roughness and cuts down the merits of using SL part. Hence, additional post-machining finishing such as traditional grinding is required. But the traditional post-machining is detrimental to part geometry and time consuming. In this study, therefore, a paraffin coating and grinding post-machining is newly proposed to improve the surface quality of SL fart. The paraffin which has suitable properties for the proposed post-machining is coated all over the part surface. By grinding the only over-coated paraffin based on boundary of the SL part surface, the surface roughness can be improved without any damage on the part. Also, it is verified that SL part finished by the proposed post-machining process can be applied for rapid tooling as pattern through manufacturing silicon rubber molding and casting test.

• 한국정밀공학회지
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• 제10권3호
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• pp.231-238
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• 1993

Mold-marking industries currently demands to reduce the tooling costs and time in mold making and to improve the productivity and quality in injection molding process. These problems can be easily solved by the laminated injection mold which is made by laser cutting metal sheets and bonding them by the brazing. Comparing with the conventional mold making technology which mainly depends on the machining, the new thchnology enables an arvitary design of cooling circuit whithout any restrictions of geometry. Therefore, it will offer high production tata of the injection molding processes. This paper evaluates the conventional and laminated injection mold making processes with a simple molding geometry, and also the cooling efficienty of the kinds of mold with the filling and cooling analyses. The results show that the laminated injection mold process takes much shorter time in tooling and cooling, and distributes temperatures more uniformly than the conventional one.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 추계학술대회 논문요약집
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• pp.31-31
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• 2003

• 한국정밀공학회지
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• 제18권8호
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• pp.18-23
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• 2001

• 한국기계가공학회지
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• 제18권11호
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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.

• 한국기계연구소 소보
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• 통권15호
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• pp.105-115
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• 1985

For the application of factory automation, a 3-axis numerical control system with personal computer and KM3701 function generator LSI chip, which has liner, circular, parabolic, logarithmic, and exponential interpolations, is developed. The developed system also has 2 control function to stabilize tooling speed and 1/1000mm step sizes.