ABSTRACT

During electrical discharge machining (EDM) drilling of small high-aspect-ratio holes, abnormal discharges between tool flank and workpiece will result in high process instability and poor shape accuracy. In order to solve this problem, dense nano-alumina insulating film is plated on the tool flank based on atomic layer deposition (ALD) to suppress the secondary discharge for the benefit of the tool’s integrity and shape accuracy. Drilling experiments on nickel base superalloy GH4099 workpiece were conducted to test machining effect of the coated brass tool. Experimental results show that it can enhance the process stability and improve the surface topography of the machined holes. The tool wear is reduced by about 21.7%, and the discharge craters and carbon black film along the tool flank are significantly reduced.

摘要

在电火花加工（EDM）钻削高深宽比小孔时，刀具后刀面与工件之间的异常放电会导致工艺不稳定和形状精度差。为了解决这个问题，基于原子层沉积（ALD）的方法在刀具侧面镀上致密的纳米氧化铝绝缘膜，以抑制二次放电，从而有利于刀具的完整性和形状精度。对镍基高温合金GH4099工件进行钻孔实验，测试涂层黄铜刀具的加工效果。实验结果表明，它可以增强工艺稳定性并改善加工孔的表面形貌。刀具磨损减少约21.7%，沿刀具后刀面的放电坑和炭黑膜明显减少。