Effect of inductance in micro EDM using high frequency bipolar pulse generator

Abstract

In this work, effect of inductance was investigated in micro EDM using high frequency bipolar pulse generator used for electrolytic corrosion prevention in deionized water. To understand behaviors of the pulses during machining according to inductance, capacitor voltage which is equal to gap voltage and inductor current were analyzed both theoretically and experimentally. Inductance affected the pulse behaviors as well as machining characteristics. In the case of high inductance, inductor current increased after discharge occurred. This increased inductor current also increased both capacitor voltage and discharge current. So, machining time decreased, and tool wear as well as side gap increased with high inductance. However, this peak value shift could lead fluctuation of gap distance and servo voltage, thus, deteriorated controllability. On the other hand, constant discharge current was achieved in the case of low inductance. Low tool wear, small side gap and fine surface were achieved with low inductance.