A critical review of electrical discharge machining for superalloys and high performance metals

The rapid growth in the use of superalloys and, subsequently, high-performance metals in industries such as aerospace, automotive, gas turbines and nuclear reactors is due to its high-temperature strength and resistance to oxidation, outstanding corrosion as well as wear resistance, and also increases thermal stability. Machining these high-performance metals is challenging because of issues like work hardening, low electrical conductivity, and reactivity at high temperatures. The difficulty increases for superalloys, which have poor thermal conductivity and electrical properties. As a result, non-traditional machining methods are being increasingly explored for these materials; however, techniques like Abrasive jet machining or Laser cutting are limited to cuts linearly. An electro-thermal method preferable Electrical discharge machining (EDM), has gained prominence for producing complex shapes with best precision. Industry 4.0 preferable context, EDM is adopted widely due to its ability to machine toughest, electrically conductive materials with a best surface quality, even for miniature/micro-scale parts. This content provides a detailed review of EDM techniques applied to superalloys over the past two decades, covering aspects such as characteristics, versatility, mechanisms, performance, and sustainability. It also discusses modelling and optimization strategies. Finally, the article identifies the current trends, research gaps, and future scope of work, including the development of green EDM. Machining performance strongly depends on electrical, wire, and flushing parameters in WEDM. Surface damage remains a key limitation, requiring improved control for reliable and sustainable use. Better control of surface features can enhance quality, reliability, and sustainability in EDM/WEDM.