Mechanism study of the combined process of electrical discharge machining ablation and electrochemical machining in aerosol dielectric

In previous studies, the electrical discharge machining (EDM) ablation technology was developed, which removed materials by using the chemical energy released from the combustion of metal instead of the energy of pulse power supply used in EDM. Although the machining efficiency was greatly improved, the problem of recast layer that generated on the machined surface during EDM ablation process had not been solved. In this study, the combined process of EDM ablation and electrochemical machining (ECM) in aerosol dielectric was investigated, which aims to solve the recast layer problem of deep hole machining by using the aerosol dielectric EDM ablation technology. The mechanism was analyzed based on numerous experiments. Mechanism analysis indicated that the combined process includes the cycle machining state of micro-electrolysis and EDM ablation. Five microcosmic stages were included in the typical combined process: metal activation at discharge point, surface metal oxidation, blocking of surface metal oxidation, rapid oxidation of internal substrate metal, and micro-electrolysis of recast layer. Contrast experiments were performed to compare conventional electrical discharge machining, aerosol dielectric EDM ablation, and combined process of EDM ablation and ECM in aerosol dielectric. Results showed that the material removal rate of the combined process was 40% less than that of the EDM ablation but was still 3.7 times more than that of EDM. Moreover, the relative tool wear ratio decreased by 53.3%, the value of corner arc radius decreased by 44.3%, and the thickness of the recast layer decreased by 42.9%.