Reduction of tool wear in non-contact electrostatic induction feeding EDM

Abstract

This paper aims to decrease the tool wear ratio in the non-contact electrostatic induction feeding method for micro electrical discharge machining (EDM). Since the electrostatic induction feeding method realizes non-contact electric feeding to the tool electrode, the tool electrode can be rotated at a high speed of 50000rpm or more. Accordingly, both material removal rate and machining accuracy can be improved. With this method, however, since discharges occur with alternating polarity, the tool electrode wear rate is higher than the conventional unipolarity pulse discharge where the polarity of workpiece is positive. Thus, in this study, in order to decreace the tool wear ratio the circuit impedance were switched alternately, so that it becomes large and zero when the workpiece was negatively and positively charged, respectively. As a result, the tool wear ratio was equivalent to the conventional unipolarity discharge.