Electrical Discharge Machining of PCD in Ultrapure Water

Sintered polycrystalline diamond (PCD) has a high degree of hardness and wear resistance, therefore, it is expected for being used for micro cutting or grinding tool. It is possible to shape the PCD micro tools with high accuracy by using electrical discharge machining (EDM) method. However, the EDMing efficiency of PCD is low, therefore, it is necessary to improve the removal rate and the electrode wear ratio. It is presumed that the EDM machinability is improved by EDMing in water. However, it is anticipated that electrochemical corrosion on the PCD surface is caused during EDMing in water. In this paper, the EDM machinability and the corrosion suppressing method in water are discussed. It is confirmed that the removal rate and the electrode wear ratio are improved by EDMing PCD in water. Moreover, electrochemical corrosion of cobalt can be suppressed by EDMing in ultrapure water with high resistivity (1.8×107 Ωcm). In addition, the electrochemical corrosion affected area can be reduced by using thin flow of EDMing fluid.