• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.393-396
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• 1997

Electro Discharge Machining (EDM) is a so-call non-conventional machining technique. This paper presents the experimental results of an EDM technique for the fabircation of microholes on #7440 pyrex glans. With various applied voltages and at various concentration of KOH solution, the glass substrate have been microdrilled using the copper electrodes of which diameters are 250$\mu\textrm{m}$ to 450$\mu\textrm{m}$, respectively. The machined throughholes have been observed the top diameter, the bottom diameter, hollow width and hole diameter of the hole, and machining time hale been measured. The experimental results show that the machining time decreases as the concentration of KOH solution increases or the applied voltage increase. Also, The top diameter increases as the concentration of KOH solution decreases or the allied voltage increases. The bottom and hollow width decreases as the of KOH solution increases or the applied voltage decreases.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.537-542
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• 2000

Wire deflection, surface roughness and roundness were observed on changing discharge time for electrical discharge machining(EDM) of STD-11 in various conditions of thickness. The wire deflection was decreased as increasing discharge time and wire tension. The deflection is the smallest at the speed of wire of 10.6m/min and the water specific resistivity of 5k$\Omega$.cm. The deflection is found to be decreased as increasing dwell time. But if the water pressure is high, it is found not to be changed after the vibration of 4sec. The component of copper(Cu) and zinc(Zn), which is the main material of wire electrode, is observed for rough wire-cutting EDM of STD-11. This phenomena is found to be similar in spite of the change of EDM energy level. But it will be improved by changing the material and the shape of wire. The roundness of middle is found to be worse than that of upper and it is increased as the thickness of material is increased.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.41-42
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• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.411-412
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• 2008

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.5
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• pp.13-20
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• 2005

Micro EDM process is generally used for machining microholes, cavities, and three dimensional shapes. For machining micro structures, first of all, micro tool electrode is indispensable and WEDG system is proposed for tool fabrication method. When using WEDG, its machining characteristics are highly affected by many EDM parameters such as applied voltage, current, rotation speed, capacitance, and pulse duration. Therefore, the design of experiment is introduced to fully understand the effect of the EDM parameters on machining tool electrode. And an attempt has been made to develop the mathematical model for predicting the size of the tool electrode by calculating spark distance. The suggested model was verified with experiment and predicted working gap distance is in good accord with the measured value.

• Transactions of Materials Processing
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• v.14 no.3 s.75
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• pp.251-256
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• 2005

3-D micro structures and micro tools were fabricated using Micro Electrical Discharge Machining (MEDM). To make micro structures, micro electrical discharge milling process was applied. During micro electrical discharge milling, electrode (tool) worn in the both axial and radial direction. To compensate tool wear which has significant influence on machining accuracy, machining path overlapping was proposed. Machining characteristics of micro electrical discharge milling was investigated in considering of depth of cut and capacitance of discharge circuit. Micro complex shaped tools were also fabricated using REDM (reverse electrical discharge machining). Sacrificial electrodes were machined through electrical discharge milling process and were used as electrode to make micro tools. Using this process several micro tools shape of 'ㄷ', 'ㅁ' and 'o' were fabricated. With these complex shaped tools, micro machining was successfully applied repeatedly.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.4
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• pp.3-10
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• 2008

Micro-electrical discharge machining (micro-EDM) is an effective method for machining all types of conductive materials regardless of hardness. Since micro-EDM is an electro-thermal process, the energy supplied by the pulse generator is an important factor in determining the effectiveness of the process. In this study, an investigation was conducted on the micro-EDM of tungsten carbide (WC) to compare the performance of transistor and resistance/capacitance (RC) pulse generators in obtaining the best quality micro-hole. The performance was measured by the machining time, material removal rate, relative tool wear ratio, surface quality, and dimensional accuracy. The RC generator was more suited for minimizing the pulse energy, which is a requirement for fabricating micro-parts. The smaller-sized debris formed by the low-discharge energy of RC micro-EDM could be easily flushed away from the machined zone, resulting in a surface free of burrs and resolidified molten metal. The RC generator also required much less time to obtain the same quality micro-hole in WC. Therefore, RC generators are better suited for fabricating micro-structures, producing good surface quality and better dimensional accuracy than the transistor generators, despite their higher relative tool wear ratio.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.4
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• pp.74-78
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• 2008

High-speed tool steels are extensively used in tooling industries for manufacturing cutting tools, forming tools, and rolls. Electrical discharge machining (EDM) has been found to be an effective process for machining these extremely hard and difficult-to-cut materials. Extensive research has been conducted to identify the optimum machining parameters for EDM with different tool steels. This paper presents a fundamental study of the surface characteristics of SKH-51 tool steel machined by micro-EDM, with particular focus on obtaining a better surface finish. An RC pulse generator was used to obtain a better surface finish as it produces fine discharge craters. The main operating parameters studied were the gap voltage and the capacitance while the resistance and other gap control parameters were kept constant. A negative tungsten electrode was used in this study. The micro-EDM performance was analyzed by atomic force microscopy to determine the average surface roughness and the distance between the highest peak and lowest valley. The topography of the machined surface was observed using a scanning electron microscope and a digital optical microscope.

• Journal of Information Management
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• v.38 no.1
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• pp.59-73
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• 2007

To construct machining databases, which are reusable and sharable their meanings, semantic metadata management is required. In this study a semantic data modeling process for machining data is developed. It combines conventional data models with ISO/IEC 11179 standard, metadata registry(MDR). Names of object classes and properties constituting data element names are identified using conventional data model while data elements are named and specified based on ISO/IEC 11179 in order to obtain semantic interoperability of data. An experimental application to electrical discharge machining(EDM) is performed to explain the process.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.8
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• pp.9-15
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• 1999

Die-sinking electrical discharge machining(EDM) for conductive ceramic matrix composite(CMC) of Tic/$Al_2O_3$ was experienced with addition of ultrasonic emission, and the results were compared with ones obtained by the EDM only. From this experimental study, the values of material removal rate(MRR) and surface roughness($R_{max}$), scanning electron microscope(SEM) micrographs, and weibull probability distribution of bending strength for the specimens were obtained and compared. The trend of MRR was found to be increased slightly with the current and the duty factor for both EDM only and EDM with ultrasonic emission. The MRR values were found to be increased for EDM with ultrasonic emission. The SEM micrographs of EDMed surface by under various operating conditions showed less micro cracks in various places. Although smaller bending strength value was obtained by EDMed surface with ultrasonic emission by weibull probability distribution analysis of bending strength.