Depth dependent characteristics of discharge and their influence on micro deep hole drilling with EDM

Abstract

In micro drilling EDM process, the discharge process dominated the machining process. In different hole depth, the change of environment of gap area (caused by the accumulation of debris, occupancy of bubble, tool wear, etc.) will lead to the change of discharge process, especially the abnormal discharge such as the high order discharge in low voltage, frequent short circuit. Moreover, the deteriorated environment of gap area will result in the seriously decrease of machining speed in the last period of machining. In this paper, the characteristic of discharge process in different hole depth has been investigated by recording and analyzing the discharge signals of voltage and current. Moreover, combined with the feed curve of micro tool, the behavior of micro tool dominated by these signals has been analyzed and the special behavior caused by abnormal discharge has been explained.