• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.04b
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• pp.66-70
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• 1993

미세드릴가공은 드릴 직경의 소경화로 발생하는 공구강성저하, 지동 발생, 칩배출 곤란 등으로 인해 수많은 기계가공 중에서도 가장 어려운 가공 중의 하나이며 이로인해 설계의 단계에서 가능한 피하고있는 실정이다. 그러나 근래 각종 제품의 소형 경량화 추세가 일어나면서 미세구멍가공 기술에 대한 중요성이 높아지고 있으며, 특히 시계부품, 소형 정밀 부품, 연료분사용 노즐, 광파이버 관련품, 우주항공기 부품 등에 수요가 급증하고 있다. 또한 최근 전기.전자 공업의 발달과 함께 등장한 표면실장기술(SMT)은 프린터 배선기판의 고밀도화를 더욱 진전시켰으며 이는 구멍밀도, 구멍지름의 미소화 등 미세구멍가공 관점에서 보완해야 할 기술적인 과제를 남겨 놓았다. 본 연구는 미세드릴가공의 메카니즘을 규명하고 그 문제점을 해결하여 미소경 드릴링 머신을 개발하는 데 주력함과 동시에그 절삭현상의 기초적인 연구를 수행하였다

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.923-928
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• 1997

An MCP (Microchannel Plate) is a secondary electron multiplier to detect and amplify electrons. An MCP has many rnicrochannels whose diameters range from 10 to 100pm and whose lengths range from 40 to 100times of the diameter. Each microchannel of the MCP amplifies electrons over IOOOtimes by the secondary electron emission. Even though MCPs have high performance for electron amplification, the application of MCPs is limited to high performance electronic equipments because of their high fabricating cost and the limit of increasing their size due to the conventional fabrication process. Therefore, in this work, microchannels of the MCP are manufactured by micro-drilling to reduce the cost of the MCP and to increase their size. Alumina green body with epoxy binder was machined for fabricating microchannels using a high speed air turbine spindle and micro-drills with diamond grinding abrasives. Then alumina MCP was fabricated through the sintering of the machined alumina green body.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.593-598
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• 2003

Ceramic plates containing many micro-holes are used in diverse applications such as MCP (Microchannel Plate). catalytic converters, filters, electrical insulators in integrated circuits, and so on. One of the efficient methods for machining many holes in ceramic plates is wet drilling of ceramic green bodies followed by sintering them. Since the strength of ceramic green bodies is much lower than the strength of sintered ceramic plate, ceramic green bodies can be drilled with high feed rate. The axial force during micro-drilling of ceramic green bodies increases rapidly at high feed rate, which induces the crack in workpiece. Therefore, the tool lift of micro-drill with respect to feed rate may be determined by the predicting increase of axial force. In this work, the axial force during micro-drilling was calculated using the chip flow model on the micro-drill tip. from which the tool life of diamond abrasive micro-drill during micro-drilling of ceramic green bodies was calculated.

• Journal of the KSME
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• v.50 no.6
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• pp.36-42
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• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.926-931
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• 2002

Although ceramic plates with many micro-hales are used as MCP (Micro-channel plate) for electron amplification, catalytic converters, filters, electrical insulators and thermal conductors in integrated circuits, the drilling of micro-hales in the ceramics is difficult because of their low thermal conductivity, high hardness and brittleness. Therefore, in this work, the machining of ceramic green body fellowed by sintering of green body was employed fur fabricating ceramic plates with many micro-holes. The micro-drilling of alumina green body was performed with diamond abrasive WC drills, and the cutting force w.r.t. drilling times was measured for the determination of toot life. From the investigation of the wear of micro-drill tip w.r.t. drilling times, the wear mechanism of tip during micro-drilling of ceramic green body was suggested.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.7
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• pp.227-232
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• 2003

In order to make a deep and precise micro-hole, electrode wear and clearance between the electrode and the workpiece are important parameters using micro-electrical discharge machining. In this study, experiments were carried out to show the characteristics of electrode wear and radial clearance with respect to the depth of machined hole. Electrode wear varied with respect to the depth of hole. With deeper machined hole, bigger clearance was observed. Also it was found that the diameter of electrode influences machining characteristics of deep holes.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.225-230
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• 2001

Small diameter drilling which take high precision in cutting work is needed more small hole and high speed working. Especially, small hole deep drilling is one of the most important machining types and its necessity and importance become more and more increasing in the whole field of industry. This paper shows the limit depths with small diameter drills using experimental analysis. The results are gained by tool dynamometer and Labview system and obtained during small diameter twist drilling system on SM45C steel for different machining conditions. The machine and tools are the CNC machining center and twist drill of diameter 1.5mm. And additionally, tool microscope show the relationship between shapes of chips and breakage shapes of small diameter drills.

• Journal of the Korean Ceramic Society
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• v.13 no.3
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• pp.55-62
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• 1976

순수한 닉켈과 금 박막을 (III)규소 단 결정위에 진공 증착시켰다. Ni/Au/Si나 Au/Ni/Si시료를 진공중에서 약 55$0^{\circ}C$로 가열하였을 때 육방정 혹은 변형된 육방정의 미소 결정들이 규소 기질위에 형성되었다. 이들 미소 결정들의 형성과정 및 조성은 X-선 회절법, scanning electron microscopy 및 scanning Auger microprobe 법을 사용하여 결정하였다. 이들 미소 결정은 NiSi2임이 확인되었다. Ni/Au/Si 시료에서는 Au-Si 공융점(37$0^{\circ}C$) 이상으로 온도가 증가됨에 따라 닉켈과 규소가 Au-Si 공융체 속으로 이동한 후 반응하여 NiSi2를 형성하였다. Au/Ni/Si 시료에 있어서의 Au-Si 공융체 형성은 닉켈 박막에 있는 바늘구멍형의 표면 결함과 관련 지을 수 있겠다. 금이 닉켈 박막의 grain boundary를 통하여 Ni/Si 계면으로 확산되어 그 계면을 습윤시킨 다음 Au-Si 공융체를 형성하였다. 이런 Au-Si 공용체는 닉켈과 규소 원자에 대한 높은 확산 매질로서 작용하여 NiSi2 형성을 촉진시켰다. 표면에 평행한 (III)규소면 위의 NiSi2 미소 결정은 유사한 육방정으로 나타났으며, 경사진 미소결정은 부등변 사변형과 유사하였다. Auger 스펙트럼 및 Ni, Au 및 Si에 대한 내층조성(indepth Composition Profiles)은 NiSi2 미소 결정이 Au-Si 공융체의 matrix에 미소 부분으로 나타났음을 보여주었다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.285-286
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• 2007

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1780-1783
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• 2003

Burrs formed in micro drilling with Ø 1.0 and 0.5 are observed. The changes of burr geometry are compared when feed rate and velocity changes. Characteristics of burr formation in 4 different workpiece materials are analyzed. The coefficient of burr geometry, CB is introduced to classify burrs according to burr height and burr types. Finally control charts are produced using the coefficient of burr geometry and burr types in each workpiece material. Data base is constructed to be used for burr expert system.