Surface characteristics optimization and investigation of dual-channel micro electrical discharge drilling on IN617 super alloy

Abstract

This article details the experimental investigation on surface roughness, spatter area and white layer thickness in micro electrical discharge machining of IN617 alloy. The alloy here is a high hardness superalloy preferred to be machined by non-conventional techniques. Here we present the micromachining behaviour of the alloy. Micro electrical discharge machining is conducted using a dual channel copper electrode and the surface characteristics are observed. Other than the traditional input factors, retraction duration of the electrode is also focussed here. White layer characteristics at different heights of the drilled hole are measured and characterized. Intensive microscopic images have been presented to detail the behaviour of the process. The behaviour of individual responses towards the various input factors has been illustrated. A multiobjective optimization model is also developed to extract the best parametric combinations at which optimal surface characteristics can be obtained.The major factor affecting the spatter area and white layer thickness is Pulse on time. The increase in pulse on time creates a high frequency of sparks which leads to rapid metal erosion at the vicinity of the electrode. In the case of surface roughness, the current was observed as the most dominant factor which corresponds to earlier studies on similar processes. Detailed microstructural analysis depicting heat affected zone, white layer thickness and surface deformities have been reported to understand the mechanism of the process.