High spindle speed micro EDM using electrostatic induction feeding method

This paper describes machining characteristics of high spindle speed micro electrical discharge machining (EDM) using the electrostatic induction feeding method. In this method, non-contact electric feeding allows the tool electrode to be rotated at high speed up to fifty thousand rpm. In micro EDM, it is considered that higher spindle speed is more useful in flushing debris particles from the gap and cooling the tool electrode. In addition, since the heat spot generated by each discharge is separated by a sufficiently long distance on the periphery of the rotating tool electrode due to the relative motion between electrodes, the locally elevated temperature can be lowered. Thus an experimental setup for high spindle speed micro EDM using the electrostatic induction feeding method was newly developed. Machining results showed that machining speed and surface roughness can be improved, and that tool wear rate can be lowered. In micro drilling, deeper micro-holes, smaller gaps and better straightness were obtained due to the high flushing efficiency at the high spindle speed.