Statistical Investigation into the Effects of Electro-Discharge Machining Parameters on WC/6%Co Composite-Part 2: Parametric Analysis and Optimization through Desirability Function (DF)

Abstract

A B S T R A C T Following the first part, in the second part, a complete parametric analysis including main effects along with the joint effects of significant two-way interactive factors are performed over each previously developed response (MRR, TWR, and Ra). It has mainly been revealed that all the responses are affected by the rate and extent of discharge energy but in a controversial manner. The MRR increases by either enhancing electrical discharge density or rising sparking frequency. Low TWRs can essentially be established by a combination of low current levels with prolonged pulse on-times or longer pulse on- times with smaller duty cycles. Less rough surfaces are achievable via a blend of either low current intensity with shorter pulse on-time or low current level with higher gap voltage. Moreover, to locate the exact numerical values of optimal settings, a multi-objective optimization technique based on the concept of desirability function was then applied to the response equations to simultaneously find optimum points of input parameters capable of producing the highest possible amount of MRR and lowest amounts of TWR and Ra within the investigated process domain in a compromise manner. The obtained predicted optimal results were then interpreted and verified experimentally to compute confirmation errors. The values of relative validation errors, all being found to be quite satisfactory (about 11% at the worst case); proves the effectiveness and reliability of suggested approach in optimizing the highly interconnected EDM parameters on WC-6%Co composite.