Micro modeling and mutli-response optimization of ECM parameters by dimensional analysis and TOPSIS

EN38 steel is mostly utilized in ships, airplane, guided missile, weapons, railway, bridges and corrosion-resisting applications. Nevertheless, low material removal rate, high hardness and inferior surface integrity restrict the conventional machining of EN38 steel. Hence, in the present work electro chemical machining (ECM) has been chosen to machine such high hardness material EN38 steel with high surface finish among the other unconventional machining process. Further the parameters were modeled using Buckingham's pie theorem to approximate Material Removal Rate (MRR) and Overcut (OC). Selection of parameters is pretty difficult in ECM because of several parameters involved in it. Hence optimization method called Techniques for order of preference by similarity to ideal solution (TOPSIS) has been used to optimize the parameters which convert the responses into single numerical indicator. Analysis of Variance (ANOVA) was performed to rank the momentous parameters. Confirmation test was accomplished and found that results are within the permissible limit. Surface defects after ECMed workpiece were analysed using Scanning electron microscope (SEM).