• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.235-240
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• 2002

In micro-EBM, it is well blown that RC circuit is suitable for discharge circuit because of its low pulse width and relatively high peak current. To increase machining speed without changing unit discharge energy, charge resistance should be decreased. But, if very low, continuous (or normal) arc discharge occurs, then increases electrode wear and reduces machining speed remarkably. In this paper, RC circuit with transistor is used to micro-EDM. Experimental results show that RC circuit with transistor can cut off continuous (or normal) arc discharge effectively if duty factor and switching period of transistor are set up optimally. Through experiments with varying charge resistance, it can be known that RC circuit with transistor has about two times faster machining speed than that of RC circuit. Especially, it has prominent rise-effect of machining speed in low unit discharge energy, so that a high-quality and high-speed micro-EDM can be realized through RC circuit with transistor.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1571-1574
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• 2005

Generally, the kerosene or the deionized water has been used for dielectric fluid in the electrical discharge machining. The spark occurs when the voltage is over the breakdown voltage and induces high temperature. In this study, the Oxygen gas is used as the dielectric. The voltage behavior in the dry Micro Electrical discharge machining is compared with that of the conventional Micro Electrical discharge machining. The dry Micro EDM has some advantages. The electrode wear isvery smaller than that of the conventional Micro EDM. The contamination in the dry Micro EDM can be drastically reduced comparing to that of the conventional Micro EDM. The Oxygen gas can be replaced as the dielectric successfully.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.158-161
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• 2005

In this paper, the precision electric discharge machining technology, the powder electric discharge machining technology, is applied to making a cold forging die for making the helical type of clutch gear. Various working conditions are investigated with emphasis on reduction of the electrode wear and enhancement of the surface roughness. Through the research work, the key technology of making the helical gear forging dies is achieved.

• 한국정밀공학회지
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• 제21권9호
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• pp.41-47
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• 2004

As mechanical structures are minimized, the demand on micro dies and molds has increased. Machining complex 3D shapes requires fabrication procedures for preparing the electrodes. Micro electrical discharge milling using a simple shape electrode can produce 3D micro structure. In this paper the machining characteristics of micro electrical discharge milling according to depth of cut and capacitance are investigated. The machining time is diminished when simple tool-paths and algorithms for changing the feedrate are applied. But a distorted bottom shape and a tapered wall shape are inevitable after machining. The distorted bottom shape and the taper angle of wall are reduced by finish machining.

• 한국정밀공학회지
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• 제27권10호
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• pp.45-51
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• 2010

Electrical discharge drilling (ED-drilling) is a widespread machining method used to bore small holes with a high aspect ratio. This paper presents additional methods by which ED-drilling can improve machining speed, tool wear, and machined surface quality. Firstly, for high machining speed, and low tool wear, a new-type electrode that was ground on one side or both sides of the cylindrical electrodes was suggested to expel debris. The debris which is generated during the machining process can cause sludge deposition and secondary discharge problems: major reasons to decrease machining speed. This new-type electrode also reduced tool wear that was due to the decrease of unstable discharge in a machining gap by helping to expel waste water and debris from the gap. Secondly, to improve the machined surface roughness, an electrolyzation process was included after drilling. This process made the machined surface smooth by means of an electrochemical reaction between an electrode and a workpiece. In this study, the machining speed, electrode wear, and surface roughness were improved by the newtype electrode and the electrolytic process.

• 한국정밀공학회지
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• 제21권2호
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• pp.177-185
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• 2004

The machining performance of wire electrical discharge machining(WEDM), such as cutting speed, surface roughness and straightness depend on the electrode, and the machining parameters are diverse and affect each other. Therefore operator must have a lot of experiences of the parameter for the better machining performance in WEDM. An approach to minimize the time for determining of parameters setting is proposed. Based on the Taguchi method, the significant factors affecting the machining performance are determined. Types of electrodes are arranged at inner array in tables of orthogonal arrays so that we can estimate machining performances of each electrode. Coating wire shows better performances than brass wire in cutting speed but it produces poor surface roughness, and two wires shows similar performance in straightness

• 한국정밀공학회지
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• 제15권12호
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• pp.55-61
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• 1998

Recently, the needs of machining technologies of very small parts have been increasing with advent of micro-revolution. These technologies have mostly used the method applied to semi-conductor production process such as LIGA, etc. But they have serious difficulties to settle down in terms of workpiece materials, machining thickness, 3-dimensional structure. Therefore. mciro-machining technology using EDM(Electrical Discharge Machining) was proposed. It is very difficult to machine the micro-parts (microshaft, microhole) using conventional machining. Micro-machining using BDM can machine the micro-parts easily because it requires little machining force. This MEDM(Micro-EDM) need the capabilities to move a electrode and control a discharge energy precisely, and the gap control strategy to maintain the optimal discharge condition is necessary. Therefore, in this study, the new EDM machine with high precision motion stage and high-performance EDM device was developed. Using this MEDM machine, we have machined microshaft and microhole with various shapes and sizes.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 추계학술대회 논문집
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• pp.176-179
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• 1998

In general, machining time by electrical discharge machining (EDM) process is much longer than that of cutting process, so rough-cut has done for the purpose of reducing machining time prior to EDM Nowadays EDM speed is improving due to the advance of EDM capacity. Therefore a new method, machining a raw material directly by EDM without rough-cut, is used widely. EDM area is varies according to the EDM position in three-dimensional EDM process, so EDM parameters should be determined adaptively based on the EDM area to increase productivity. However it is difficult to calculate EDM area corresponding to the EDM position the EDM workers who have experience in shop floor determine machining parameters by experience. This paper proposes a method for determining EDM parameters based on EDM area corresponding to EDM position.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 추계학술대회 논문집
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• pp.117-122
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• 2002

Electrical discharge machining uses thermal energy from electrical discharge, while wire electrical discharge machining (WEDM) technology is widely used in conductive material machining. This paper proposes a method for evaluating the characteristics of wires in WEDM. In order to evaluate the wire processing performance, processing speed and roughness, straightness, corner processing have been assessed with precision experiment equipment and image processing including Laplacian filtering with various threshold levels.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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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.