• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.389-394
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• 1993

Die making process is classified into design,manufacturing,polishing,assembly, and performance test. Die polishing is not a machining process by cutting edge of tool, but it is finishing by relative cutting movement under the surface contact between grinding particles and workpiece, and this process comprised 30~40% of total manufacturing hours. However, die polishing process is still performed by the skilled workers. Now a days, it is very difficult to secure skilled workers due to the hardworking environment and this situation will be getting worse in the future which has great difficulty of dies and molds industries.This process has the common problem on the elimination of tedious manual polishing among the tool making industries. Therefore this study is aimed at the development of an automatic polishing attachment which could be attached onthe spindle of CNC machine tool and controlled by the NC program data created by CAD/CAM system. As a result, this study will contribute the realization of automatic fine polishing process and improvement of quality level of dies and molds.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.417-422
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• 2000

In the process of die manufacturing, according to increasing demand of die and molds, the efficient machining of dies and molds has been increased. However, while the cutting process has been automated by the progress of CNC(computer numerical control) and CAD/CAM, the polishing process still depends on the experienced knowledge of an expert. Also, even when workers are skilled in polishing dies. it takes much time to obtain the required roughness and smoothness on the surface of a die. Moreover, many workers gradually avoid doing polishing work because of the poor working conditions caused by dust and noise. Therefore, to improve productivity and to solve the potential shortage of skilled workers, a user-friendly automatic polishing system was developed in this research. The developed polishing system with five degrees of freedom is able to keep the polishing tool normal to the die surface during operation and is able to maintain a pressure constantly by the developed pneumatic system. Also, to evaluate polishing performance of the developend system and find the polishing conditions, the various polishing experiments were carried out.

• Design & Manufacturing
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• v.9 no.2
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• pp.6-9
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• 2015

The objective of manufacturing knowledge sharing platform is to convert the production experience like a worker's know-how into quantitative values, to construct database of the process technologies and to share the technologies systematically via web portal service. In addition, the knowledge sharing platform contains the total production processes of automobile and mobile products such as information of experts, facilities, and cutting-edge R&D outputs. Automobile, telecommunication mobile, and semiconductors account for a large amount of Korea's export industry rate. These industries need production technology which is a result of converting worker's know-how and R&D. Manufacturing knowledge portal aims to enable transforming production experience such as worker's know-how into standardized form for constructing database and sharing technologies systematically. Manufacturing knowledge portal can contribute to small and mid-sized manufacturing companies with further improvements.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.2
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• pp.14-20
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• 1998

Automatic finishing process requires the development of high efficient and precision abrasive machining method for dies and molds. This study describes the evaluation of the finishing characteristics, such as surfrace roughness, topography and material removal depth of the electrolytic mixed abrasive machining methods. Experimental setup is composed of 3 axis machining center, a newly developed finishing attachment with constant pressure, electrode and electrolytic bath. Finally, we achieved a successful result that surface roughness is $0.01\mu$m Ra and material removal depth is $120\mu$m using electrolytic(0.8A. 30V) mixed abrasive (#400 CBN, #320 SiC) machining method.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.1047-1050
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• 2000

As the progress of new industrial products or parts technology, the precise and fine machining technologies are needed more and more. Micro fabrication technology of these products are usally consisted of mechanical machining or MEMS technology. Direct machining by mechanical method is not applicable to mass production. MEMS technology also has several problems such as low mechanical strength, bad surface roughness and difficulty of 3 dimensional machining. In this study, we introduce several micro fabrication technology to make micro molds and dies and our project to develop these machining technology.

• Design & Manufacturing
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• v.10 no.2
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• pp.50-54
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• 2016

In the semiconductor industry the final products were checked for several environments before sell the products. The burning test of memory and chip was implemented in reliability for all of parts. The memory and chip were developed to high density memory and high performance chip, so circuit design was also high integrated and the test bed was needed to be thin and fine pitch socket. LGA(Land Grid Array) IC socket with thin wall thickness was designed to satisfy this requirement. The LGA IC socket plastic part was manufacture by injection molding process, it was needed accuracy, stiffness and suit resin with high flowability. In this study, injection molding process analysis was executed for 2 and 4 cavities moldings with runner, gate and sprue. The warpage analysis was also implemented for further gate removal process. Through the analyses the total deformations of the moldings were predicted within maximum 0.05mm deformation. Finally in consideration of these results, 2 and 4 cavities molds were designed and made and tested in injection molding process.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.3
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• pp.119-129
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• 1995

In this paper, the inclined endmilling process with a 3-axis machining center using inclined jigs is introduced for the purpose of reducing overall Dies/Molds machining time and improving the machining accuracies. In order to analyze the cutting mechanism of a given endmill more accurately, the unification of the cutting mechanism model of 3-different- kind endmills is carried out by using a nose radius as a parameter. By adding radial runouts as a parameter which influences on surface roughness, the superposition method which defines the effective cusp height superposing the cutter mark height and the conventional cusp height is advanced. And 3-D suface topography predicted in this paper looks like the surface normally observed in practice. Through machining experiments, the adequacy of the superposition method was confirmed.

• Transactions of Materials Processing
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• v.23 no.1
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• pp.5-9
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• 2014

Although much research has been conducted to reduce the thickness of PET bottles in order to save manufacturing costs, the challenge remains of guaranteeing mechanical strength for top-loaded thin PET bottles. The current study investigates the large deformation characteristics of a circle shaped PET bottle and a square shaped PET bottle when compressively loaded using FEA. The arc length method is used in the nonlinear FEA to understand the buckling phenomenon. For PET bottles with the same capacity, the circle shaped bottle shows more resistance to buckling and compression loading than the square shaped bottle.

• Design & Manufacturing
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• v.10 no.1
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• pp.1-6
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• 2016

In this study, the modification structure design of insulation displacement connector developed was considered for simplification of assembly process. The modified connector consisted terminal, wafer and fitting nails. The separation behavior under locking condition for pitch 1.25mm wire to board connector was measured and the apparatus for the test was made. The maximum restraining force was measured about 4.5kgf that was bigger value than the specification limit. And the pulling force of a wire was also indicated about 2.3kgf.

• Design & Manufacturing
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• v.1 no.1
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• pp.27-32
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• 2007

In the optical application demand for high quality lens is increasing. Plastics lenses are demanded more than glass lenses for large size lenses as well as micro-size lenses. It is difficult to apply typical straight cooling channels of injection mold to lens molding due to its non-uniform temperature distribution. In this study, we manufactured molds for plastic lenses with the conventional cooling channels and conformal cooling channels produced by the DMLS process. We evaluated cooling performance for the 2 molds by injection molding experiment. Also, uniformity of the temperature distribution was tested by infrared camera and temperature monitoring. We confirmed that the cooling performance and temperature uniformity with the conformal cooling channels is much improved from the ones with the conventional. The cooling time with the conformal cooling channels was reduced 30% compared with the conventional cooling channels.