Electrical discharge machining–based hybrid machining processes: A review

Electrical discharge machining is one of the widely used noncontact-type advanced machining processes in which material removal takes place due to melting and vaporization by thermal energy of electric sparks. Electrical discharge machining has the capability of machining difficult-to-cut materials such as superalloys, advanced ceramics, and composites with complex shapes at both macro- and micro-levels. But its application is limited to electrically conductive materials. Other limitations include low material removal rate, high tool wear rate, recast layer formation, and geometrical inaccuracy in the form of taper and overcut. To overcome such limitations, the mechanism of electrical discharge machining has been combined with the mechanism of one or more other machining/physical/chemical processes. The mechanism of two constituent processes may be applied simultaneously or sequentially to constitute the hybrid machining process. It has been found that the performance of hybrid machining processes is better than the constituent processes. This article presents the comprehensive review of the research work carried out so far in the area of electrical discharge machining–based hybrid machining processes. It discusses about the experimental and theoretical studies of electrical discharge machining–based hybrid machining processes to elucidate the effects of various control factors or input parameters on process performances. This article includes modeling and optimization studies and discusses the future trend of the research work in this area.