Research on the mechanism and process of EDM of polycrystalline diamond

Abstract Traditional electric discharge machining (EDM) uses the copper electrode to machine polycrystalline diamond (PCD), and the machining efficiency and machining quality have been poor. To improve the machining efficiency and machining quality, this study uses white copper as the electrode to machine the surface of the PCD workpiece and adds graphene powder to the dielectric for mixed powder EDM. The surface properties and processing mechanism of PCD under different processing methods were analyzed by scanning electron microscope (SEM), X-ray diffraction (XRD), and Raman spectroscopy, and the surface quality and processing efficiency of PCD were analyzed by material removal rate (MRR) and surface roughness (SR). The results showed that the MRR of the white copper electrode increased by 65% compared with that of the purple copper electrode at low parameters, and the MRR increased again by 87% after adding graphene, and the SR decreased by 13%. The graphitization of PCD diamond processed by the white copper electrode was greater than that of the purple copper electrode by Raman spectroscopy and XRD analysis, and the addition of graphene increased the graphitization again. The results show that when processing with copper electrode, the way of processing PCD is mainly to remove the binder, and the effect of processing diamond particles is not obvious; when processing with white copper electrode, making diamond graphitization is the main removal method, and after adding graphene in the dielectric, the removal method changes to a combination of diamond graphitization and high discharge energy removal.