Simultaneously counting of positive and negative pulse parts to predict tool wear in micro-EDM milling

In micro electrical discharge machining (EDM) processes, resistor-capacitor (RC) discharge pulses often display a reverse current flow at the end of the pulse, most likely due to parasitic inductance in the discharge circuit, especially at high frequency. As negative pulses generally lead to high electrode wear, this paper quantitatively analyses the contribution of the positive and negative pulse parts on tool wear in micro-EDM milling when a commercial RC based generator is employed. The characteristics of both positive and negative pulse parts were studied and the tool wear per discharge (TWD) of each part was determined separately. The tool wear was then ultimately predicted by the sum of the number of occurrences of each part multiplied its specific TWD. The proposed tool wear prediction method was finally experimentally validated.status: publishe