Machining and optimization of zircaloy 2 using electrical discharge machine

Abstract

Electrical discharge machining (EDM) is highly efficient non-traditional machining process, which is extensively used to produce punches and moulds, dies, semi finished and finished parts for space, locomotive industry, and medical industry. The electrically conducting materials, which are difficult to machine using traditional processes, can be machined with higher accuracy by EDM. Expensive rare earth materials, hard materials, and brittle materials have been successfully machined using EDM in literature. There is scant literature in machining of ceramics and refractory materials with EDM. Zircaloy-2 is an expensive rare earth materials widely used in nuclear power plant core and structural component. It has high melting point, corrosion resistance, and low neutron cross-section area make it suitable for nuclear application. In this work Zircaloy-2 was machined with the help of EDM. Process parameters i e. pulse-on-time, pulse-off-time, polarity, tool electrode materials, tool electrode design, and peak current were considered. The response parameters i.e. tool wear rate, surface roughness, material removal rate, radial overcut, radial undercut, and taper angle were evaluated. The effect of tool electrode geometry and electrical conductivity was considered in this thesis, for which literature evidence is not available. Experimental design using Design of Experiment (DOE) is followed by Optimization of machining response parameters. Optimization of parameters is carried out using multi-criteria-decision-making methods like grey relation analysis, response surface methodology, R-method, and VIKOR method. newline newlineTo achieve desired objective, Zircaloy-2 is machined using EDM with different levels of process parameters to obtain optimal value of response parameters. The following procedure was adopted to achieve desired objective. (a) Selection of significant machining parameters i.e. polarity, pulse-on-time (Ton), pulse-off-time (Toff), tool electrode materials, tool electrode design and peak current (Ip) to machine Zir