Active gap capacitance electrical discharge machining of polycrystalline diamond

This paper introduced a novel active gap capacitance electrical discharge machining (AGC-EDM) method for high efficiency machining of polycrystalline diamond. Graphene was used for the first time in an EDM process to increase the gap capacitance, which would result in enlarged inter-electrode discharge explosive force and higher processing stability. The new principle and machining mechanisms were introduced; an equivalent circuit model was established; and factors that affect the machining performance were analyzed. In order to valid the theory and assumptions and investigate the effectiveness of the new approach, EDM experiments and comparative study were conducted. Test results showed that discharge explosive force in the new AGC-EDM was increased dramatically and the machining process became more stable. The material removal rate in AGC-EDM was found to be more than 10 times higher than that of the normal EDM while the relative electrode wear was reduced by 70 %.