Critical analysis of surface integrity parameters and dimensional accuracy in powder-mixed EDM
Deepti Ranjan Sahu, Amitava Mandal
Abstract
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 (Cd), 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, Cd, and RLT, improve only in graphite PMEDM, whereas they deteriorate in alumina PMEDM. Furthermore, maximum mean spacing (Psm) and least peak density (Rpc) 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.