ABSTRACT
Electrical-discharge machining (EDM) process is one of the extensively used processes for machining difficult-to-cut electrically conductive materials. With miniaturization, EDM is also capable of machining in the micro and nano domains. EDM finds applications in industries dealing in die and mold making, automotive, aerospace, biomedical, and others. In EDM, dielectric breakdown initiates the electrothermal process responsible for material removal from the electrodes. Molten material is removed from the machining zone by dielectric flow. Dielectric is, therefore, an inherent part of the EDM process that significantly affects the machining performance. In the early inception of EDM, hydrocarbon-based dielectric particularly kerosene was popular due to its distinct advantages, such as high dielectric strength and better insulation properties. However, it had certain demerits such as inflammability, decomposition emitting harmful fumes, toxic waste, and aerosols, leading to health hazards. Since then, rapid development toward making EDM a sustainable-friendly process by using dielectric with minimal or no harmful effects while maintaining similar accuracy and precision of the process has occurred. This chapter provides an extensive overview of the different dielectrics as well as the development of dry to near-dry EDM processes to show the pathway to create a sustainable EDM process.
