Machining characteristics of hard and brittle insulating materials with mist-jetting electrochemical discharge

Abstract

A new electrochemical discharge machining (EDM) method that combines slotted metal wheel and mist-jetting electrolyte was proposed based on existing problems in the traditional electrolytic EDM compound machining of hard and brittle insulating materials. The physical process of this new method can be divided into four stages, namely the gas film generation, discharge channel formation, material removal, and deionization. We analyzed the inter-polar voltage and current characteristic during machining and found the suitable machining voltage and range of rotation speed for the slotted metal wheel to achieve stable electrochemical discharge machining. The voltage should be more than 220 V, and the rotation speed of the slotted metal wheel should range from 1200 to 1800 rpm during machining. By analyzing the waveform of the voltage and current during mist-jetting electrochemical machining, we found that the machining status included direct gas spark discharge and electrochemical gas spark discharge and that the electrochemical gas spark discharge was primary. Finally, we realized the stable machining of Al₂O₃ ceramic by using the proposed method. The efficiency of material removal was 53.5 mg/min, and the surface roughness of the machining surface was Ra 5.4 μm.