Improvement of Surface Roughness of Nickel Alloy Specimen by Removing Recast Layer In Wire Electric Discharge Machining

Abstract

In this investigation, experimental work and computational work are combined to obtain improvement in the surface roughness of nickel alloy specimen, the machining is carried out by means of CNC wire electric discharge machining (WEDM). Brass wire is used as the tool electrode and nickel alloy (Inconel600) is used as the work piece material. The machining parameters such as Pulse-On time (Ton), Pulse-Off time (Toff), Peak Current (Ip), and Bed speed are considered as input parameters for this project. Surface roughness and Recast layer are considered the output parameters. The experiments with the pre-planned set of input parameters are designed based on Taguchi's orthogonal array. The surface roughness is measured using stylus type roughness tester and the thickness of the Recast layer is measured using Scanning Electron Microscope (SEM). The results obtained from the experiments are fed to the Minitab software and optimum input parameters for the desired output parameters are identified. The software uses the concept of analysis of variance (ANOVA) and indicates the nature of effect of input parameters on the output parameters and confirmation is done by validation experiments. Once the recast layer thickness is obtained Chemical Etching and abrasive blasting is performed in order to remove the recast layer and again the surface roughness is measured by using stylus type roughness tester. Finally from the obtained results it was found that there was significant improvement in the Surface roughness of the nickel alloy material. In addition using regression analysis this work is stimulated by computational method and the results are obtained.