As a method of processing cemented carbide, sinking electrical discharge machining (EDM) is generally used. However, typical surface defects, such as cracks, microcraters and recast layers, lead to decreased surface integrity and may result in an inadequate tool life. Currently, the recast layer is removed by polishing. However, this process requires a long machining time, causing a high production cost of metal molds. Therefore, it is desirable to eliminate these surface defects. Thus, an on-the-machine surface modification technology in EDM, for the complete elimination of surface defects, was developed in this study. The surface defects are eliminated using a sinking electrical discharge machine in which surface integrity machining for EDM (SIME process) is introduced after applying a finishing processing. The SIME process is carried out by applying voltage to the constant gap between the electrode and the workpiece in deionized water. It can be considered that a recast layer including cracks is selectively eliminated by the dissolution of cobalt through the electrolytic action during the SIME process. As a result, the surface defects generated by EDM could be completely eliminated by incorporating the SIME process into EDM.
抄録全体を表示