Electric discharge machine process parameters optimization for additively manufactured copper–graphene tool

The overall cost associated with a product manufactured using electric discharge machine (EDM) incorporates tooling cost as one of the significant components. In the present study, process optimization was attempted for EDM parameters to minimize the electrode wear and cavity size variation and maximize the material removal rate. The machining was carried out using composite tool fabricated using a two-step methodology that involves an indirect 3D printing technique, rapid tooling, and pressureless microwave sintering. Composite samples having rectangular cross-section (35 mm  × 25 mm × 10 mm) were fabricated. The central composite design technique was utilized to plan and conduct experiments. EDM process parameters—discharge current, pulse-on time, and duty factor—were considered to investigate their effect on electrode and material removal rate and cavity dimension deviation. Multi-objective optimization was performed using genetic algorithm, and an optimized set of machining parameters 6 A discharge current, 180 µs pulse-on time, and 75% duty factor was obtained. Machining of D2 steel was performed at these parameters, and an electrode wear rate of 1.81 mg/min, material removal rate of 97.35 mg/min, and dimensional deviation of 1.42% were obtained. To assess the process capability, a complex-shaped tool was fabricated and considered for machining. A dimensional comparison demonstrated an effective method for manufacturing intricately shaped composite electrodes, achieving both a low electrode wear rate and a high material removal rate.