Electic discharge machining apparatus

摘要

An electric discharge machining apparatus is provided which is capable of sufficiently reducing stray capacitance (C1) between an electrode (1) and a workpiece (7) to improve surface roughness of a machined workpiece by electric discharge machining. A first switching device (11a) is provided in a feeding line (4a) between an electrode (1) and a first machining power source (2) for supplying a first electric discharge energy for a rough machining, and a second switching device (11b) is provided in a feeding line (4b) between the workpiece (7) and the first power source (2) in an electric discharge circuit in which the workpiece (7) and a workpiece mounting table (6) are electrically insulated. In performing a finish machining, a second electric discharge energy smaller than the first machining energy is supplied from a second machining power source (3) between the electrode (1) and the workpiece (7) with the first and second switches opened. <IMAGE>