• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.1003-1007
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• 2002

Micro-EDM is generally used far machining micro 3-D structure. For micro-EDM, first of all, micro-electrode fabrication is needed and WEDG system is proposed for tool electrode fabrication method. When tool electrode is fabricated using WEDG system, its characteristics are under the control of many EDM parameters. Also relations between the parameters affect electrode fabrication. In this study, experiments are carried out to analyze effects of EDM parameters on micro-electrode fabrication. Experimental method and analysis are used to experimental design method. Factors used in experiments are composed of applied voltage, capacitance, wire feed rate, spindle rotating speed, machining time. As a result of experiments, wire feed rate, machining time and capacitance is proportional to gap distance(material removal), the other parameters(applied voltage, spindle rotating speed) and relations between the parameters have little influence on machining.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.42-45
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• 2004

Electrochemical discharge machining (ECDM) has been found to be suitable for the micro-hole machining of nonconductive materials such as ceramics or glass compared with existing conventional and also non-conventional machining methods. However this machining process has some problems such as low geometric accuracy and low machining efficiency due to the random spark generation at the end of the electrode. This paper proposes the methods to improve the geometric accuracy of micro-hole using powder mixed ECDM process. The experimental results show the effects of powder producing improved geometric accuracy of machined hole and decreased concentration of spark energy.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.7
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• pp.167-175
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• 1996

Work roll wear in the cold rolling of steel strip is strongly affected by rolling materials, rolling conditions and lubrication. Tests were performed to find the effects of rolling materials under the same lubricating conditions. Surface roughness of cold rolled steel strip as well as the coating technique itself is quite improtant in obtaining high image clarity of electronic products and car outer panels. Therefore this paper reviews for improvement of roughness and peak count about the surface of Cr coated work roll is investigated from the actual temper mill. The conclusions were obtained as follows; 1) Work roll wear in the cold rolling of steel strip is strongly affected by carbon contents of rolling materials, but there is not a separating force and total reduction ratio. 2) The roughness of strip surface is larger in the direction of width than in roll direction. 3) The electro-discharge textured roll has more uniform roughness distribu- tion than shot blasted roll and it's life time is two times longer than shot blasted because it has more harmonic wave roughness, and the higher peak count of surface roughness. 4) The life time of Cr coated work roll is 2 times longer than that of shot blasted work roll and variation of peak count, roughness and life time of Cr coated work roll is similar to electro-discharge texturing work roll. 5) The proper Cr coating thickness is 10 .mu. m at the work roll of temper mill.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.370-370
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• 2010

최근 자연모사를 통한 초저마찰 연구가 활발히 진행되고 있으며 리소그라피, 레이져 가공법 등의 다양한 방법을 통해 표면구조 제어가 시도되고 있다. 본 연구에서는 자장여과 아크 플라즈마 이온 소스를 이용한 WC-Co 및 SCM 415 금속소재의 표면구조 형상제어를 통해 저마찰 특성을 시도하였다. 자장여과 아크 소스는 90도 꺽힘형이며 5개의 자장 코일을 통해 아크 음극에서 발생된 고밀도($10^{13}\;cm^{-3}$ 이상) 플라즈마를 표면처리 대상 기판까지 확산시켰다. 공정 압력은 알곤가스 1 mTorr, 아크 방전 전류는 25 A, 플라즈마 수송 덕트 전압은 10 V이다. 기판 전압은 비대칭 펄스 (-80 %/+5 %)로 -600 V에서 -800 V까지 인가되었으며 -600 V 비대칭 펄스 인가시기판으로 입사하는 알곤 이온 전류 밀도는 약 $4.5\;mA/cm^2$ 이다. WC-Co 시편의 경우 -600 V 전압 인가시, 이온빔 처리 전 46.4 nm(${\pm}12.7\;nm$)의 조도를 갖는 시편이 5분, 10분, 20분동안 이온빔 처리함에 따라 72.8 nm(${\pm}3\;nm$), 108.2 nm(${\pm}5.9\;nm$), 257.8 nm(${\pm}24.4\;nm$)의 조도를 나타내었다. SCM415 시편의 경우 -800 V 인가시, 이온빔 처리 전 20.4 nm(${\pm}2.9\;nm$)의 조도를 갖는 시편이 20분동안 이온빔 처리함에 따라 275.1 nm(${\pm}43\;nm$)의 조도를 나타내었다. 또한 주사전자현미경을 통한 표면 형상 관찰 결과, 이온빔 식각을 통해 생성된 거친 표면에 $3-5\;{\mu}m$ 직경의 돌기들이 산발적으로 생성됨을 확인했다. 마찰계수 측정 결과 SCM415 시편의 경우, 이온빔 처리전 마찰계수 0.65에서 조도 275.1 nm 시편의 경우 0.48로 감소하였다. 본 연구를 통해 이온빔 식각을 이용한 금속표면 제어 및 저마찰 특성 향상의 가능성을 확인하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.1017-1020
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• 2002

The pure Ti is taken annealing process for one hour at 90$0^{\circ}C$. The pure Ti is sufficient for ASTM B348 Grade2. The rolling mill roll the Ti-8Ta-3Nb(wt%) which became vacuum melting in arc furnace until the length is about 45mm and the thickness is about 6.05mm. Then it is made 6mm$\times$6mm$\times$44mm by wire cutting with EDM and it is made ∮ 6mm by rough cutting with the general purpose lathe. The machining accuracy of implant parts in the dental and medical science are decided by dimension, shpe, straightness, surface roughness. It is difficult to cut for the Ti alloy. It is caused problems of straight degree and surface roughness to the Ti alloy have many cases which length is smaller than diameter in cutting. Total 24 specimens different kind of 4 alloies are used in experiment to gain a cutting property. According to the cutting velocity, cutting depth, cutting temperature, feed and clearance angle experiments are performed. Conclusively it is expected that cutting depth of 0.5mm, feed velocity of 0.07mm/rev and cutting velocity of 80m/min could make a suitable result.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.389-394
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• 2005

Microfactory is effective method for machining micro size component. Electro-chemical machining can be more suitable to a microfactory than other machining methods in terms of maintaining high accuracy. Surface profile of EDM Machined component is predicted by micro EDM simulation using superpositioning spark crater. Planar motor and micro pump are developed to construct microfactory system.