State of the art in processing of shape memory alloys with electrical discharge machining: A review

Shape memory alloys (SMAs) have been well known for their superior and excellent properties which makes them an eligible candidate of paramount importance in real-life industrial applications such as; orthopedic implants, actuators, micro tools, stents, coupling and sealing elements, aerospace components, defense instruments, manufacturing elements, bio-medical appliances, etc. In spite of their exceptional properties, the effective processing of these alloys is always seen as a challenge by researchers around the globe. The present article has been therefore attempted to explore the numerous studies conducted to process these alloys by employing the principles of electrical discharge machining (EDM) and its allied approaches. The NiTi-based SMAs have been revealed to be explored majorly among the several types SMAs. The several investigations carried out in the domain of EDM, Wire-EDM, and some conventional processing of various types of SMAs have also been critically reviewed and reported. It also highlights the numerous experimental, theoretical, modeling, and optimization-based researches attempted in EDM of SMAs. It was also reported that the proper selection of process variables, tool electrode, and the dielectrics can substantially improve the overall process effectiveness. Among the various accessible EDM variants used for the processing of SMAs, attempted by the umpteen investigators, the wire-cut EDM process has been revealed as the most explored one for cutting SMAs than the other allied processes such as: die-sinking EDM and powder-mixed EDM. The micro-machining applications of EDM have also been deliberated briefly. The last section of the article reports about the opportunities and the challenges for future research.