Current Research Trends in Electrical Discharge Machining: A Review

EDM is an unconventional electro thermal machining process used for manufacturing geometrically complex or hard material parts that are extremely difficult-to-machine by conventional machining process. The process involves a controlled erosion of electrically conductive materials by the initiation of rapid and repetitive spark discharges between the tool and work piece separated by a small gap of about 0.01 to 0.50. This gap is either flooded or immersed in a dielectric fluid. The controlled pulsing of direct current between the tool and the work piece produces the spark discharge. The EDM process that we know today is a result of various researches carried out over the years. EDM researchers have explored a number of ways to improve the sparking efficiency with various experimental concepts. Despite a range of different approaches, every new research shares the same objectives of achieving high metal removal rate with reduction in tool wear and improved surface quality. This paper reviews the vast array of research work carried out within past decades for the development of EDM. This study is mainly focused on aspects related to surface quality and metal removal rate which are the most important parameters from the point of view of selecting the optimum condition of processes as well as economical aspects. It reports the research trends in EDM.