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RISS 인기검색어
- 검색키워드
- 저자 : Yoke San Wong (검색결과 5 건)
- 무료
- 기관 내 무료
- 유료
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Surface Characteristics of Tool Steel Machined Using Micro-EDM
Mohammed Muntakim Anwar,Wong Yoke San,Mustafizur Rahman 한국정밀공학회 2008 International Journal of Precision Engineering and Vol.9 No.4
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.
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A Comparative Study of Transistor and RC Pulse Generators for Micro-EDM of Tungsten Carbide
Muhammad Pervej Jahan,Yoke San Wong,Mustafizur Rahman 한국정밀공학회 2008 International Journal of Precision Engineering and Vol.9 No.4
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 We. 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.
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Surface Characteristics of Tool Steel Machined Using Micro-EDM
Anwar, Mohammed Muntakim,San, Wong Yoke,Rahman, Mustafizur Korean Society for Precision Engineering 2008 International Journal of Precision Engineering and Vol.9 No.4
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.
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A Comparative Study of Transistor and RC Pulse Generators for Micro-EDM of Tungsten Carbide
Jahan, Muhammad Pervej,Wong, Yoke San,Rahman, Mustafizur Korean Society for Precision Engineering 2008 International Journal of Precision Engineering and Vol.9 No.4
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.
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Study of Workpiece Vibration in Powder-Suspended Dielectric Fluid in Micro-EDM Processes
Gunawan Setia Prihandana,Muslim Mahardika,Mohd Hamdi,Yoke San Wong,Norihisa Miki,Kimiyuki Mitsui 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.
Abstract. In micro-EDM (electrical discharge machining), improper removal of debris causes short-circuiting between a tool electrode and a workpiece and in turn, prevents continuous machining process. Therefore, a remarkably longer period of time is required to fabricate a through hole than that would be required when no short-circuiting took place. In order to solve this problem, the dielectric fluid is immersed with graphite nano powders to reduce machining time and improve surface quality due to the less frequent of arcing between the tool electrode and the workpiece. However, excess powders become debris and subsequently deteriorate the efficiency of machining. To fully exploit the effects of the suspended powders, we introduced vibration of the workpiece in order to remove the debris in the small gap between the workpiece and electrode efficiently. The experimental results showed that combination of these techniques improved machining stability, assured continuous machining processes, and significant reduction of the machining time. Reduction of the machining time and the surface roughness of the workpiece after machining were investigated with respect to the powder concentrations when the workpiece was vibrated at 1000 Hz.
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