Machining Performance of Inconel 718 Using High Current Density Electrical Discharge Milling

This article proposes a high current density electrical discharge milling for machining Inconel 718. The proposed power supply comprises a pulse generator with high voltage and a DC power source with high current. The pip graphite electrode and the workpiece are connected to the negative and positive poles of the power supply, respectively. Benefiting from efficient flushing and high current density, the maximum material removal rate (MRR) achieved 15,062mm(3)/min with a relative electrode wear ratio (REWR) of 1.73%. The effects of peak current and injection flushing pressure on the MRR and REWR were investigated. Experiments showed little differences between the thickness of recast layer with the peak currents of 150A and 920A, and the thickness was less than 50 mu m. It is also evident that the microcracks within the recast layer penetrated into the base material and propagated along the grain boundar.