Effect of cryogenic treated tool electrode during electric discharge drilling (EDD) of Inconel 800

Abstract

Inconel 800 is widely used material for construction of equipment and which requires corrosion resistance, heat resistance, strength, and stability. These properties make them potential material for components in aerospace industries, gas turbine etc. The conventional drilling in Inconel 800 sometimes become uneconomical because of low productivity, poor quality and inaccurate geometry. Electric Discharge Drilling (EDD), a variant of EDM, is one such process which can produce high accuracy holes, thus improving overall productivity and reducing the cycle time. This paper describes an experimental study on EDD of Inconel 800 using self-developed EDD set up. The holes were drilled using copper tool electrode. The effect of tool electrode treatment (cryogenic and untreated), discharge current (Id), pulse-on time (TON), gap voltage (Vg) and tool electrode speed (N) on material removal rate (MRR), electrode wear rate (EWR) and radial overcut (ROC) have been studied. The experimental runs were carried out using L18 (21 × 34) orthogonal array and result were analyzed using Taguchi’s methodology. It was observed that the optimal parameter setting for MRR are TET (cryogenically treated), Id (15A), TON (120 µs) and N (200 rpm), for EWR- TET (cryogenically treated), Id (9A), TON (120 µs) and N (200 rpm) and for ROC- TET (cryogenically treated) and Id (12 A). It was also observed that with the use of cryogenically treated tool electrode an appreciable improvement in the MRR by 9.89%, EWR by 21.73% and ROC by 36.15% is achieved, which confirm the viability of using the cryogenically treated tool electrode and relevance to industry.