Abstract Die-sinking electrical discharge machining (EDM) is widely used in die and mold-making industry. Finish EDM conditions are often selected to produce good quality surfaces. Attempts to enhance the finishing capabilities using ultrasonic vibration and powder-added dielectric medium have been reported in the literature. However, the changes in the gap phenomena with ultrasonic assistance and powder addition have not been analyzed. In this article, finish EDM of hardened D3 steel has been carried out based on full factorial design of experiment with three levels of setting voltage, setting current and pulse on time. The performance of ultrasonic assisted and graphite powder-added EDM are evaluated by analyzing the voltage and current pulse trains in finishing operation for the first time. Based on two new parameters, namely energy expended over a second (E) and ratio of energy due to sparks in relation to total discharge energy (PF), the results are discussed and also compared with those obtained with conventional EDM for selected conditions. Even though E of 102.9 J (PF = 0.862) with ultrasonic vibration is higher than E of 43.0 J (PF = 1.0) with powder mix, the molten metal is removed effectively from the gap by ultrasonic vibration which results in a relatively better surface. The micrographs of cross-section and surface of the workpieces obtained using optical and scanning electron microscopes, respectively, also reveal their relative performance.

中文翻译：

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通过脉冲序列研究超声振动和粉末添加的电火花成型加工性能

摘要 电火花成型加工（EDM）广泛应用于模具制造行业。通常选择精加工 EDM 条件来生产高质量的表面。文献中已经报道了使用超声波振动和添加粉末的电介质来提高整理能力的尝试。然而，尚未分析超声波辅助和粉末添加对间隙现象的变化。本文在全因子实验设计的基础上，采用整定电压、整定电流和脉冲导通时间三个等级对淬硬D3钢进行了精加工电火花加工。首次通过分析精加工中的电压和电流脉冲序列来评估超声辅助和添加石墨粉的电火花加工的性能。基于两个新参数，即一秒内消耗的能量 (E) 和火花产生的能量与总放电能量 (PF) 的比率，讨论了结果，并与传统 EDM 在选定条件下获得的结果进行了比较。尽管超声波振动的 E 为 102.9 J (PF = 0.862) 高于粉末混合物的 E 43.0 J (PF = 1.0)，但通过超声波振动可以有效地从间隙中去除熔融金属，从而产生相对更好的表面。分别使用光学和扫描电子显微镜获得的工件横截面和表面的显微照片也揭示了它们的相对性能。尽管超声波振动的 E 为 102.9 J (PF = 0.862) 高于粉末混合物的 E 43.0 J (PF = 1.0)，但通过超声波振动可以有效地从间隙中去除熔融金属，从而产生相对更好的表面。分别使用光学和扫描电子显微镜获得的工件横截面和表面的显微照片也揭示了它们的相对性能。尽管超声波振动的 E 为 102.9 J (PF = 0.862) 高于粉末混合物的 E 43.0 J (PF = 1.0)，但通过超声波振动可以有效地从间隙中去除熔融金属，从而产生相对更好的表面。分别使用光学和扫描电子显微镜获得的工件横截面和表面的显微照片也揭示了它们的相对性能。