Electrical discharge machining (EDM) drilling is based on the principle of electrical discharge machining. In a liquid medium, an electrode tube is used as the tool electrode to perform pulsed spark discharge on the workpiece. The instantaneous high temperature erodes the metal material, achieving the purpose of perforation. The electrode is typically a hollow, thin copper tube, with a diameter ranging from 0.3mm to 3.0mm. The machining medium passes through a small hole in the center of the copper tube, serving to cool the electrode and flush out the discharge erosion products. During machining, the electrode wire moves continuously up and down vertically to maintain a suitable discharge gap.
This is a non-contact machining process with no significant mechanical cutting force. Therefore, it is suitable for machining high-hardness, high-strength conductive materials and can directly penetrate inclined or curved surfaces. Unlike wire EDM, which uses a reciprocating metal wire as the electrode, and EDM forming, which uses a forming electrode, EDM drilling machines use a hollow tubular electrode that moves vertically.