Electrical discharge machining (EDM) process is popular for machining conductive and difficult-to-cut materials, but low material removal rate (MRR) and poor surface quality are major limitations of the process. These limitations can be overcome by adding the suitable powder in the dielectric. The powder particles influence electric field intensity during the EDM process which in turn improve its performance. The size (micro to nano) and properties of the mixed powder also influence the machining efficiency. In this regard, the objective of the present work is to study the performance of EDM process for machining Inconel 825 alloy by mixing Al₂O₃ nanopowder in deionized water. The experimental investigation revealed that maximum MRR of 47 mg/min and minimum SR of 1.487 µm, which are 44 and 51% higher in comparison to conventional EDM process, respectively, can be achieved by setting optimal combinations of process parameters. To analyze these observed process behavior, pulse-train data of the spark gap were acquired. The discharge waveform identifies the less arcing phenomenon in the modified EDM process compared to conventional EDM. Further, surface-topography of the machined surface was critically examined by capturing field emission scanning electron microscopy and atomic force microscopy images.

In recent years, wire-electrical discharge machining (WEDM) has gained popularity in the industry due to its capability to generate complicated shapes in exotic materials, irrespective of their hardness. Conventional machining of Nimonic C-263 superalloy is an extremely difficult and costly process due to its high hardness and tool wear rate. The present research work investigates the influence of the WEDM process parameters on different performance measures during machining of Nimonic C-263 superalloy. A mathematical model for all four important performance measures, namely, cutting rate, surface roughness, spark gap, and wire wear ratio, was developed and the responses were used for studying the interrelationship between performance measures and process parameters. The optimal settings of operating conditions were predicted using desirability function. The effectiveness of multicut strategy was also investigated in the article.

In this experimental study, the effects of major laser process control parameters, such as the laser power, beam scanning speed and assisting gas flow rate, on cut surface integrity defined by the kerf width, taper percentage, and the extent of heat affected zone (HAZ) were investigated. Response surface methodology (RSM) along with central composite design (CCD) of the experiment was used to optimize the process parameters to get better-cut surface quality. The optimum values of process parameters corresponding to cut surface with minimum defects are laser power 260 W, cutting speed 4500 mm per min, and assistance gas flow rate 14.23 l/min and the corresponding kerf width, taper percentage, and the width of HAZ are found to be 163.7 µm, 5.75%, and 573.28 µm. The confirmation experiments have been conducted that provide favorable results with an error of 2.70%, 1.87%, and 0.36%, for kerf width, taper percentage, and width of HAZ, respectively.

This study aims at evaluating the effectiveness of Powder-Mixed Electrical Discharge Machining (PMEDM) in improving the surface integrity. The surface quality has been analyzed in terms of surface roughness, waviness, surface texture, surface crack density (SCD), crack depth (C_d), residual stress, microhardness, and recast-layer thickness (RLT) followed by chemical analysis. It has been found that the addition of graphite and alumina powder improves the average surface roughness. But other critical parameters, viz., SCD, C_d, and RLT, improve only in graphite PMEDM, whereas they deteriorate in alumina PMEDM. Furthermore, maximum mean spacing (P_sm) and least peak density (R_pc) confirmed the highest degree of spark distribution in graphite PMEDM. Apart from these, tool wear rate (TWR) and dimensional deviation of the machined profile have also been studied. Addition of powder has increased the TWR and hence taper in the machined profile. However, due to uniform distribution of spark in graphite PMEDM, maximum circularity is obtained. To analyze the observed results, all the dielectrics have been characterized. The improved surface integrity parameters of the machined surface are found to be in agreement with the changes in properties of dielectric due to addition of powders.