The structures of small-holes are widely used in auto industry, aerospace, medical science and micro electronics. Electrical Discharge Machining (EDM) is capable of machining all conductive materials with neglectable forces and irrespective to the material hardness and strength. These characteristics of EDM establish its predominant situation in the fields of small-hole machining. A stable and high efficiency EDM process depends on a robust process control system, including the servo control, the pulse cont...