Productivity improvement of micro EDM process by improvised tool

Abstract

Micro electric discharge machining (μ-EDM) is a widely used process for machining of difficult to machine materials. The occurrence of arcing and short circuiting in micro electric discharge drilling (EDD) is a common problem which limits the aspect ratio achieved during the process. The present study is focused on the improvement in response characteristics by eliminating the occurrence of arcing and short circuiting. These problems can be addressed by modifying the tool electrode geometry. Although, EDD using shaped tool electrodes improve response characteristics as proven by the previous studies, but time spent in electrode fabrication must also be considered as it affects the overall productivity. Considering the literature related to EDD using shaped tool electrodes, the proposed electrode has been found to have minimum electrode fabrication time i.e. 9min for an electrode length of 3.2mm. Therefore, the proposed electrode is capable of producing holes of high aspect ratio with minimum electrode fabrication time. The proposed electrode was also found to be effective in eliminating the accumulation of debris in the machining zone. Moreover, the need of flushing during the process has been totally eliminated making it a self-flushing electrode. The mechanism of removal of debris is well explained based on the images captured using a high speed camera. The performance of the proposed electrode was evaluated with respect to response characteristics such as material removal rate, tool wear rate, aspect ratio, taper angle and corner radius of the drilled hole. A substantial increase of 300% in aspect ratio was recorded using the designed electrode as compared to the solid cylindrical electrode for the hole diameter of 0.8mm.