Experimental investigation on EDM of Si3N4-TiN using grey relational analysis coupled with teaching-learning-based optimization algorithm

Electric discharge machining of silicon nitride-titanium nitride (Si3N4-TiN) ceramic composites was conceded for making square and circular profiles. Five imperative machining parameters namely current, pulse-on time, pulse-off time, dielectric pressure and spark gap voltage have been contemplated to resolve the response characteristics like material removal rate, electrode wear rate, surface roughness and geometrical tolerances. Multi Criteria Decision Making techniques like GRA and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) are used to discover the optimal set of machining parameter combinations to accomplish maximum efficiency of all the responses. Also, Metaheuristic or nature inspired algorithm namely GRA coupled with TLBO algorithm is engaged for obtaining global optimum parameters. The parameters like the current, pulse-on time and spark gap voltage have the indicative impact on the responses like MRR, EWR and geometrical tolerances. It is acknowledged that the current and pulse-on time are most significant parameters among others. The optimal EDM parameters based on GRA and TOPSIS methods for obtaining better responses are current - 10 amps; pulse-on time - 8 mu sec; pulse-off time - 4 mu sec; dielectric pressure - 20 kg/cm(2) and spark gap voltage - 32 V.