Effect of copper electrode material on surface quality in EDM of heat-treated C45 steel nut blanks

Electrical discharge machining (EDM) has been increasingly adopted in manufacturing facilities and industrial plants in Vietnam, particularly in the production of molds and tooling with complex geometries. In practice, EDM is predominantly applied to the machining of recessed, concave, and through-hole features, such as stamping dies, bottle molds, and plastic injection molds. In contrast, punch-type components, such as punches used in nut forming, are still largely produced by conventional cold machining methods, which are characterized by relatively low productivity. This study addresses the need for more efficient machining approaches capable of ensuring both productivity and quality in complex shaping applications. Focusing on punches typically fabricated from high-cost 9XC tool alloy steel, the research investigates the influence of copper electrodes on surface roughness during the EDM process applied to nut blanks made of hardened C45 steel.