Experimental investigation on the discharge stability in micro-EDM based on finite-successive pulses discharge method

The discharge stability is crucial for micro-electrical discharge machining (EDM) performances such as material removal rate, tool wear ratio and surface integrity. In this study, based on the finite-successive pulses discharge method, the discharge stability of micro-EDM was systematically explored by focusing on the effective discharge rate (EDR) and uniformity of craters distribution (UCD). Specifically, a novel uniformity index method was adopted to achieve the mathematical characterization of UCD. The effects of the essential parameters including open-circuit voltage, peak current, pulse duration, duty cycle, electrode rotating speed, gap width and dielectric medium on EDR and UCD were assessed by analysis of variance. The results indicated that the pulse duration is a significant parameter for the EDR, while the peak current is significant parameter for both EDR and UCD. Moreover, the influencing mechanisms of machining parameters on EDR and UCD were also discussed. Finally, the optimal parameter combinations were obtained through signal-to-noise (S/N) ratio response graphs, and the feasibility to optimize machining parameters based on EDR and UCD was confirmed by verification experiments. The results of this work are expected to be helpful to achieve parameter optimization from a clearer perspective, and further improve the micro-EDM performances as well.