Trends in electrical discharge machining of Ti- and Ni-based superalloys: macro-micro-compound arc/spark/melt process

Abstract Electrical discharge machining (EDM)—one of the unconventional manufacturing processes—has found intensive applications in high-performance engineering sectors, that is, precision manufacturing. The superior manufacturing benefits exhibited by EDM in terms of surface quality, microstructure, micron-scale manufacturability and complex profiles have established it as one of the highly used noncontact machining processes. Moreover, EDM is one of the efficient ways of machining Ti and Ni-based superalloys used in oil–gas, aerospace, and automobile industries. However, superior material properties make the conventional EDM approach difficult to machine these exotic materials. Integrating the arc machining module to the EDM system, the hybrid electrical discharge and arc drilling can increase the material removal rate and hence the machining performance. This is due to the high thermal intensity of the sparks/arcs imparted by this compound process. Additionally, ongoing research on EDM shows that further performance improvement is possible by the integration of multiple unconventional manufacturing processes. For instance, the integrated use of arc machining with EDM revealed improved machining time, part accuracy and surface integrity. As such, this chapter presents the compounding of EDM with different arcing/sparking/melting processes along with detailed working principles and examples. Moreover, the performance of these processes is evaluated in terms of multifarious criteria, that is, surface integrity, material removal rate, electrode wear ratio, machining time, precision dimension, etc. The technology assistance process (i.e., vibration) for micro-EDM to promote better machinability is also presented. Finally, the machine tool capability to lead future micromanufacturing is highlighted for the combination of various machining processes with micro-EDM in a single machine to meet the growing demand of miniaturization.