Abstract: Two high-precision and high-performance micro electrical discharge machining (EDM) machine tools are designed and developed with independent intellectual property right. Some key technologies about the micro EDM machine tool are deeply researched. A macro-micro servo control system based on piezoelectric ceramic can realize 3.42 nm displacement, and vibration feeding serve, which can greatly improve the gap state of micro EDM, and enhance the machining efficiency and quality. A reverse machining system for fabricating micro- elec-trode, which combined the block electrode reverse machining system and wire electrode discharge grinding (WEDG), is able to make the microelectrode on-site, and the diameter of such an electrode can reach 4 mm. After that, the detecting circuit with a multiple-sensor fusion system for discharging process can solve the problem of gap state detection and identification for micro EDM process. No sparkle maintaining voltage exists during discharging of RC power supply. This discovery provides a new solution to solve the problem of decreasing single pulse energy. Thus the least single pulse energy based RC power supply of ultra-micro energy can be down to pico-joule, which is the basis of micro EDM. The last part shows that the implementation of these EDM machine tools verifies that the micro EDM can be performed stably, and can achieve the high operating quality. The micro EDM machine tool is especially suitable to process the hole whose aperture is around 50～200 mm.

Key words: Electrical discharge machining (EDM), Machine tool Macro and micro servo, Micro machining, Ultra-micro energy