Experimental Determination of Machining Responses in Machining Austempered Ductile Iron (ADI)

Abstract

This work investigates the machining characteristics of Austempered Ductile Iron (ADI) using Electrical Discharge Machining (EDM) process with copper as an electrode. Experiments have been carried out to analyze the effect of each parameter on the machining characteristics, and to predict the optimal choice for each EDM parameters such as peak current, pulse on time, pulse off time and tool geometry. Three different specimens were austenised at 900° C for 90min and then austempered in a salt bath at 360° C, 380° C, and 400° C for 120min. Experiments have been designed as per Taguchi's L18 orthogonal array. Analysis of variance (ANOVA) is used to find the level of significance of machining parameters. Machining responses such as the metal removal rate (MRR), Tool wear rate (TWR), surface roughness (SR) and taper angle (DVEE) for entrance – exit of the tool was studied while machining the Austempered Ductile Iron (ADI) with copper as an electrode. Discharge current, Pulse on time and Austempering temperature are found most influential parameters on each performance measure. Tool geometry is found the least influential parameters.