Analysis of electro discharge machined surfaces of EN-31 tool steel

Abstract

In this study, experiments were performed to determine parameters effecting surface roughness (SR) along with structural analysis of surfaces with respect to material removal parameters. Experimental work was conducted on EN-31 tool steel with copper, brass and graphite as tool electrodes with kerosene oil as dielectric fluid. The data compiled during experimentation has been used to yield responses in respect of material removal rate (MRR) and SR. Detailed analysis of structural features of machined surface was done by using Scanning Electron Microscope (SEM) and optical microscope to understand the mode of heat affected zone (HAZ), which alternatively affects structure of machined workpiece and hence tool life. While investigating electric discharge machining (EDM) surface by micrographs, it was observed that molten mass has been removed from surface as ligaments and sheets. In some cases, it is removed as chunks, which being in molten state stuck to surface. All three specimens machined by different electrodes showed different pattern of HAZs.