An experimental investigation emphasizing surface characteristics of electro-discharge-machined Inconel 601

Abstract

The paper reports an experimental investigation on electro-discharge machining (EDM) of Inconel 601 using copper electrode tool. Based on L27 orthogonal array (OA), experiments have been conducted by varying five controllable process parameters [viz. peak current (Ip), pulse-on time (Ton), gap voltage (Vg), duty factor (τ) and flushing pressure (Fp)] within the selected experimental domain. The following responses in relation of surface topography of the machined endproduct, i.e., surface crack density (SCD) and white layer thickness (WLT), have been investigated for each of the experimental runs. Utility theory in conjugation with Taguchi’s optimization philosophy has been proposed herein to select the most favourable process environment (optimal parameters setting) to ensure optimal (minimal) SCD and WLT, simultaneously. Apart from parametric optimization, SEM micro-graphs revealing surface morphology in terms of cracks, crater, pock mark, globule of debris, and deposition mark of the EDMed Inconel 601 have been analysed in detail and correlated with chemical composition, residual stress and micro-hardness data. Different types of cracks have been identified as well. Effects of significant process parameters on surface crack density and white layer thickness have been graphically represented.