Optimization of Electrical Discharge Turning Process using Taguchi-Grey Relational Approach

Abstract

Electrical discharge turning (EDT) is a unique form of electrical discharge machining (EDM) process, which is being especially developed to generate cylindrical forms and helical profiles on difficult to machine materials at both macro and micro levels. Generally, wire-cut electrical discharge machining is used for turning because it is not concerned with electrode tooling cost. The process variant die-sinking electrical discharge machining can also be effectively used to generate free-form cylindrical geometries on hard to cut materials. In EDT process a precise spindle is incorporated with conventional die-sinking EDM machine to rotate the workpiece. Axially symmetric parts can be manufactured by feeding the shaped conductive strip of copper into the rotating workpiece. Thus, a mirror image of the tool is formed on the circumference of the workpiece. In this way, cylindrical workpiece can be made with small tools. This study presents an experimental investigation of electrical discharge turning of titanium Ti-6Al-4 V alloy. The objective was to investigate the influence of machining parameters including peak current, pulse-on time, gap voltage, spindle speed and flushing pressure on performance characteristics at reverse polarity. Taguchi-grey relational approach based on multi objective optimization has been used to optimize material removal and surface roughness simultaneously.