High Frequency Micro Wire EDM for Electrolytic Corrosion Prevention

Abstract

Electrolytic corrosion occurs if water is used as a dielectric fluid during micro EDM process, ultimately resulting in serious inaccuracies on a machined part. In order to prevent electrolytic corrosion, a high frequency AC power source was developed for micro wire EDM processes. This study presents an analysis based on the electrical double layer theory. Based on this theory, the effects of electrolytic corrosion decrease as the AC power source frequency increases. As an anti-corrosion power source, a 13.56 MHz AC power source was developed using class E power amplifier. This new power source produced discharge current pulses with a peak of 1.1 A and a duration of 20 ns. With the new power source, micro shafts were successfully machined by micro wire EDM using tap water without exhibiting electrolytic corrosion. In comparison to a conventional RC type power source, the high frequency AC power source with tap water ensured 7 times higher material removal rate while maintaining similar surface roughness (< 0.1 mu m R(a)).