Multi Response Optimization of Wire Electric Discharge Machining With Analytic Hierarchy Process

Abstract

Modernization of mechanical industry has lead to the increase in demand for hard and tough materials and thus various non traditional methods have been developed in order to machine such hard and tough materials. Wire Electric discharge machine is one of the most commonly used machine which is employed in machining of conductive metals of any hardness or that are difficult or impossible to cut with traditional methods. WEDM is one of the most popular machining methods in present industry which specializes in cutting complex shapes or geometries. The literature survey has revealed that very less work has been done in order to achieve optimal levels of process parameters for AISI 304, AISI 410, EN 31 and H21 using molybdenum wire electrode. Also machine operators perform machining operations on these materials using their operational skills and experience. These materials have been selected keeping in view their application and hence machined using Concord United WEDM, Model-DK7740CH. The objective of the present study is to study the effect of different process parameters viz. peak current, pulse on time, pulse off time and work piece on the response variables such as material removal rate, surface finish, kerf width and gap current using molybdenum wire electrode (0.18 mm diameter). Taguchi design methodology has been chosen for design of experiment and L16 orthogonal array has been selected for present study. Two different sets of experiments based on L16 OA have been designed using two different workpiece materials (AISI 304 and AISI 410 for first set of experiment and EN 31 and H21 for second set of experiment). Analysis of variance and main effect plot have been used to find the significant process parameters and their effect on the response variables. The process parameters for each workpiece materials have been optimized using analytic hierarchy process.