Abstract: Unilateral conductibility and superficial electrochemical properties represented in n-type germanium crystal electrical discharge machining (EDM) are researched in a bid to reveal the special characteristics of this material during EDM process. It is discovered that the n-type germanium crystal EDM cannot be sustained, and this is due to electrolysis emergence on the contact surface of providing power and consequently forming non-conducting insoluble oxide blocking the gap between the contact surfaces. In order to prevent electrolysis from occurring, a method to apply carbon paste coating on the contact surface is designed. On the other hand, for the purpose of removing non-conducting insoluble oxide on the contact surface, the method of electrode servo power providing is designed. Then the two power providing methods are compared. Results show that the former is able to improve the power providing condition of n-type germanium crystal for a certain period of time but can’t achieve the long-term stability, while the latter can assure the steady lower inter-electrode resistance and the persistent effect of power providing. Through the wire-cut EDM (WEDM) experiment, special phenomena of semiconductor material in electrical discharge machining are preliminarily revealed, which include inter-electrode current climbing up, thermal stress erosion being dominant in the discharge erosion and polarity effect required to be analyzed in depth.

Key words: Electrical discharge machining, Germanium crystal, Mode of providing power, Semiconductor, Servo mode of providing power