Manufacturing of Wire-Drawing Die Using a Removal Method of Heat-Affected Zones by Oxidation of Cemented Carbides

Heat-affected zones (HAZs) are generated by electrical discharge machining of cemented carbides. A surface modification method using an oxidation treatment of cemented carbides has been proposed as a removal method for the HAZs. The HAZs can be completely removed in the form of oxides through the oxidation treatment. In this study, a wire-drawing die with a bearing diameter of 10 mm was fabricated by wire electrical discharge machining (WEDM). Subsequently, this surface modification method for finishing the die was introduced to improve the die quality and to reduce the die manufacturing time. As a result, the surface integrity of the die is superior to that of the die finished by a conventional removal method. Defects such as cracks partially exist on a polished surface in the latter case. The HAZs are completely removed in 3 minutes by this oxidation treatment. It only takes 20 minutes to polish the die by incorporating this method into the die manufacturing process. The completion time of a wire-drawing die is approximately 50% shorter than that obtained by the conventional removal method.