This study deals with the application technology of Electrical Discharge Coating(EDC) to improve cutting tool(drill) life by Electrical Discharge Machining. Nowadays, multi-coated tools by PVD or CVD are developed to carry out high efficiency metal cutting. But, life of re-grinding coated tools decrease by approximately under one-half of original one. Beside, re-coating technology is difficult to employ a fine and complex cleaning procedures for removing some waste from tools surface. Therfore, the recycle usage of worn tools are not avairable as common technology. In this report, some experiment are done to be cleared above mentioned problem whether EDC drills are available or not in compare with TiN coated drills. The main result of experiments are as follows; (1) The layer made with EDC has less voids defect, and has exactly fine crystal structure on the surface of tool. (2) The hard layer by EDC can be applied to major flank surface after re-grinding of worn drills. (3) Life of EDC drills become to same life of new TiN coated drill or to be over than original life. (4) EDC drills show a high resistance against chipping of tool edge in compare with TiN coated drill during hole machining.
