Multi Response optimization of characteristics of AISI D2 steel using utility concept and harmonic search method machined with different tool materials

Abstract

Electrochemical machining (ECM) is widely used in manufacturing industry due to its many superior properties like no tool wear, good surface finish. Any conducting material can be machined with high dimensional accuracy and intricate designs can be easily carved on difficult to machine materials irrespective of their hardness. The magnetic properties and hardness etc. of the substrate material remain unchanged after machining with ECM due to lesser temperature generation during machining. The main challenge for using this method is that the specific energy requirement for the process is very large (about 150 times that required for conventional processes). Hence optimization techniques are necessary to get the best set of parameters in order to enhance the quality of machining. In the present work AISI D2 steel is machined with three different types of tools, copper, brass and graphite. Comparative study of the output responses obtained by machining with different tools was done to examine the advantage provided by individual tool material on the performance characteristics. Design of experiments was carried out using Response surface methodology combined with utility concept to convert the multi response system into an equivalent single response objective function by giving equal weightage to all the responses. Finally the responses were optimized by the nature inspired optimization technique Harmonic search algorithm as it takes lesser time and fewer calculations to optimize the responses. It was found that graphite tool gives the highest value of MRR and lowest value of overcut as compared to copper and brass tool while surface roughness obtained by machining with brass tool was found to be minimum.