Electrical discharge machining (EDM) is one of the earliest non-traditional machining processes. EDM process is based on thermoelectric energy between the workpiece and an electrode. Material removal rate (MRR) is an important performance measure in EDM process. Since long, EDM researchers have explored a number of ways to improve and optimize the MRR including some unique experimental concepts that depart from the traditional EDM sparking phenomenon. Despite a range of different approaches, all the research work in this area shares the same objectives of achieving more efficient material removal coupled with a reduction in tool wear and improved surface quality. The paper reports research on EDM relating to improvement in MRR along with some insight into mechanism of material removal. In the end of the paper scope for future research work has been outlined.

In this article, parametric optimization for material removal rate (MRR) and tool wear rate (TWR) study on the powder mixed electrical discharge machining (PMEDM) of EN-8 steel has been carried out. Response surface methodology (RSM) has been used to plan and analyze the experiments. Average current, duty cycle, angle of electrode and concentration of chromium powder added into dielectric fluid of EDM were chosen as process parameters to study the PMEDM performance in terms of MRR and TWR. Experiments have been performed on newly designed experimental setup developed in laboratory. Most important parameters affecting selected performance measures have been identified and effects of their variations have been observed.

The experimental analysis on the influence of duty factor and powder particle size on discharge energy, material removal rate and surface integrity is made during powder mixed electrical discharge machining process. Molybdenum-di-sulfide (MoS2) powder particles of two different size viz. 40μm (micro) and 90 nm (nano) are used. During experimentation duty factor is varied as 2, 4, 6, 8, 10 and 12. A comparative evaluation on the effect of using two size of molybdenum-di-sulfide powder particle in dielectric medium is studied. For all duty factors, micro powder offered high discharge energy and better surface finish compared to that of nano powder. Nano powder offered high material removal rate compared to that of micro powder. The occurrence of series discharge during powder mixed electrical discharge machining is observed using pulse train generated in gap and using scanning electron microscope image of machined surface. The e energy dispersive X-ray spectroscopy analysis of machined surface reveals the deposition of molybdenum-di-sulphide from dielectric medium for both micro and nano powder mixed electrical discharge machining process.