• 한국정밀공학회지
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• 제17권1호
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• pp.27-33
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• 2000

This paper presents a method for determining machining parameters in 3-dimentional electrical discharge machining(EDM). The parameters are the peak value of currents, the pulse-on time, and the pulse-off time. It is known that they influence the performance of EDM more than the other else. The parameters are determined from the discharge area between a tool electrode and a work piece. The discharge area is directly influenced by the geometry of a tool surface and the tool discharge position. The discharge area on a tool discharge position is calculated from intersection curves between the tool surface and a horizontal plane. The grid search method is applied to determine the intersection curves. An example is introduced to show that the machining parameters are obtained from the surface geometry of a tool electrode.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.218-222
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• 2002

Micro-EDM is generally used far machining micro holes, pockets, and 3-D structures. For micro-EDM, first of all, micro-electrode fabrication is needed and WEDC 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 about electrode surface integrity on micro-electrode fabrication. Experimental method and analysis are used to experimental design method. Factors used in experiments are composed of capacitance, resistance, pause time, wire feed rate, spindle rotating speed. As a result of experiments, capacitance and resistance affect electrode surface.

• 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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• 제23권4호
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• pp.146-152
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• 2006

In micro electrochemical machining (ECM), electrodes should be prevented from unfavorable oxide and Passive layer formation on the machined surface or overall corrosion of the entire surface. Generally, metal electrodes corrode, passivate or dissolve in the electrochemical cell according to the electrode potential. Therefore, each electrode must maintain its stable potential. Tn this paper, the stable electrode potentials of tool and workpiece were determined using the potentiodynamic polarization test and verified experimentally considering machining stability and surface quality. Stable workpiece electrode potentials of two different passive materials of 304 stainless steel and nickel were determined in the 0.1 M sulfuric acid. Experimental results show good machined surface and fast machining rate using the determined electrode potentials.

• 한국정밀공학회지
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• 제20권12호
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• pp.191-197
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• 2003

As mechanical components are miniaturized, the demand on micro die and mold is increasing. Micro mechanical components usually have high hardness and good conductivity. So micro electrical discharge machining (MEDM) is an effective way to machine those components. In micro cavity fabrication using MEDM, it is observed that the bottom surface of cavity is distorted. Electric charges tend to be concentrated at the sharp edge. At the center of the bottom surface, debris can not be drawn off easily. These two phenomena make the bottom surface of the electrode and workpiece distort. As machining depth increases, the distorted shape of electrode approaches hemisphere. This process is affected by capacitance and the size of electrode. By using a smaller electrode than the desired cavity size and appropriate tool movement, bottom shape distortion can be prevented.

• International Journal of Precision Engineering and Manufacturing
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• 제6권4호
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• pp.44-48
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• 2005

As mechanical components are miniaturized, the demands on micro die/mold are increasing. Micro mechanical components usually have high hardness and good conductivity. Micro electrical discharge machining (MEDM) can thus be an effective way to machine those components. In micro cavity fabrication using MEDM, it is observed that the bottom surface of the cavity is distorted. Electric charges tend to be concentrated at the sharp edge, and debris cannot be drawn off easily at the center of the bottom surface. These two phenomena make the bottom surface of electrode and workpiece distort. As machining depth increases, the distorted shape of the electrode approaches hemisphere. This process is affected by both capacitance and the size of electrode. By using a smaller electrode than the desired cavity size and appropriate tool movement, bottom shape distortion can be prevented.

• 한국정밀공학회지
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• 제25권7호
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• pp.139-144
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• 2008

Micro electrochemical machining was investigated to machine micro internal features. This method uses a micro disk tool electrode and can easily machine micro features inside of a micro hole, which are very difficult to make by the conventional processes. In order to limit the machining area and localize the electrochemical dissolution, ultra short pulses were used as power source and a micro disk electrode with insulating layer on its surface was used as a tool electrode. By electrochemical process, internal features, such as groove array, were fabricated on the stainless steel plate.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1996년도 춘계학술대회 논문집
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• pp.137-142
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• 1996

Magnetic-electrolytic-abrasive polishing system(MEAPS) was developed for machining national standard electrode and its finishing characteristics was analyzed. The paper describes the operational principle of MEAP system by experimental results. The finishing characteristics and optimal finishing condition for national standard electrodes were experimented and analyzed. As a result, MEAPS can improve straightness as well as surface roughness.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1999년도 춘계학술대회 논문집
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• pp.245-250
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• 1999

The experimental study of die-sinking electrical discharge machining for alloy tool steel of STD-11 with circular electrode was conducted for various conditions of the peak current and duty factor with the change of internal size of electrode for distributing the amount of dielectric flow through the electrode. From this study, the material removal rate(MRR) was found to be increased with the peak current and duty factor. The more MRR was obtained for the case of electrode inside diameter of 10mm. The surface roughness and roundness values were analyzed regularity under various conditions, and these values were not affected by the inside diameter change of electrode.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1999년도 춘계학술대회 논문집
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• pp.251-255
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• 1999

In last paper, it was suggested electrochemical polishing method using the point electrode tools. It was aimed that Machining rate in ECM using the point electrode method should be ultimately small and also high dimension accuracy and surface integrity should be fine. In this paper, the machining characteristics were investigated by using the several types of electrolyte.