Review of electrochemical discharge machining technology for insulating hard and brittle materials

With excellent characteristics such as strong wear resistance, high hardness and good insulation, insulating hard and brittle materials such as optical glass and engineering ceramics are widely applied in modern industry. However, it is very difficult to machine these advanced insulating hard and brittle materials with traditional machining methods such as cutting or grinding, by which the dimensional accuracy or processing efficiency is very low. Electrochemical discharge machining (ECDM) process is an emerging non-traditional machining process that relies on spark discharge and chemical etching to etch materials and has great potential for machining various insulating hard and brittle materials. This paper introduces the gas film formation process and material etching mechanism during ECDM and summarizes the current research status in terms of electrical parameters, electrode structure, electrode motion, auxiliary liquid supply, and electrolytes that affect the processing performance of ECDM. Multi-energy field combined processing techniques have also attracted the interest of researchers. Various hybrid machining processes are introduced. Finally, the currently researches are summarized and some improvement measures that can improve the processing performance of ECDM are discussed for future research.