The addition of powder in the dielectric modifies some process variables and creates the conditions for obtaining high surface quality. Powder Mixed Electrical Discharge Machining (PMEDM) is relatively a new development in the direction of enhancement of process capabilities of EDM and considerably improves the surface integrity by reducing the formation of white crystals and scratches, heat affected zone, craters, hollow cavities and micro-cracks on EDMed surface. However, Low Surface Finish is main problem which are being faced in EDM of Inconel-718, one of the most useful Super alloy. There is needed to look at various possibilities for improving SF of Inconel-718. One way is to use some powders in dielectric fluid of EDM. A few investigations on PMEDM of Inconel-718 indicate that pure Silicon (Si) powder mixed with dielectric gave encourage results. The present work is also in the same direction and detailed experimental study has been conducted. The average grain sizes i.e. 15μm, 25μm and 40μm of Si powder particles and their concentration are taken as input parameters. Final surface roughness, surface profiles and SEM photographs have been obtained at various combinations of the input parameters. On an average, 40% improvement in SF has been observed, when Inconel-718 was machined by PMEDM instead of EDM. Comparison of SEM photographs reveals noticeable decrease in surface cracks when Inconel-718 was machined with PMEDM.
Surface roughness, Si powder, Average grain size, Powder concentration, Inconel-718
