Study on Influence of Tool Electrode Material on Discharge Delay Time in EDM

Abstract

The purpose of this paper is to clarify the influence of tool electrode materials on discharge delay time in electrical discharge machining (EDM). In this study, Copper, brass, and zinc were used as tool electrode materials. Experiments of single pulse discharge were conducted for both polarities, with and without debris particles put in the gap, respectively. The experimental results showed that regardless of the machining polarity and existence of debris particles, under the same machining conditions, the average discharge delay time was longest when using brass as the tool electrode material followed by copper, and shortest using zinc. This tendency agrees with the order in which the work function of electrode material decreases, indicating that under the same machining conditions the discharge delay time is largely affected by the work function of the electrode material. When the debris particles were mixed in the dielectric liquid, the average discharge delay time was significantly short compared with that when debris do not exist in the discharge gap and decreases with the increase of debris concentration. Since the average discharge delay time was decreased to one tenth with the inclusion of debris particles, the effect of work function on the delay time was insignificant and the effect of the debris concentration was decisive.