Simulation and experimental analysis of alternating-current phenomenon in micro-EDM with a RC-type generator

In micro electrical discharge machining (micro-EDM) with a RC-type generator, due to the oscillation voltage on a sparking gap caused by the parasitic parameters in a discharge loop and the smaller discharge capacitor, the normal-discharge is usually accompanied by the alternating-current. In this research, the alternating-current phenomenon was analyzed comprehensively through theoretical analysis, electrical simulation and experimental verification. An electrical discharge model based on real experimental waveforms was provided, and the machining influences of alternating-current were investigated. It was found that the alternating-current was likely occur when the discharge capacitor restored significant energy at the end of the first normal-discharge, and it remarkably contributed to material removal on the workpiece under some conditions, which improved the machining efficiency at a limited expense. So, the process servo control and the strategy for tool wear prediction and compensation should consider the alternating-current effects or utilize it in the finishing regime and high-accuracy machining applications.