Copper alloy MS46 has recently been developed as a metal mold material for shell mold core in place of cast iron FC which has conventionally been used. In this paper, the electrical discharge machining performances of copper alloy MS46 are experimentally investigated, analyzing the crater shape generated by a single pulse discharge, the metal removal rate, the electrode wear rate, the surface finish and so on. Then the surface integrity of MS46 for metal mold is evaluated. Main conclusions obtained in this study are as follows:
(1) The metal removal rate in EDM of MS46 is the same as that in cast iron FC.
(2) No electrode wear EDM of MS46 is difficult because of less material adhesion to the surface of electrode than that in case of cast iron.
(3) EDMed surface of MS46 has some excellent properties for metal mold such as better surface finish than that of cast iron, no crack on the machined surface and harder recast layer than base material.