Optimization of Parameters in Wire-EDM for Powder Metallurgical Cold Worked Tool Steel

Abstract

Wire electric discharge machining is a non-traditional material removal process used to manufacture components with intricate shapes and profiles. In the present research, wire wear ratio of WEDM machine during machining of P/M cold worked tool steel is studied. Selection of optimum machining parameters for obtaining minimum wire wear is a challenging task in Wire electric discharge machining due to the presence of a large number of process variables and complicated mechanisms. In general, no perfect combination of parameters exists for getting the minimum wire wear. These requirements enable the manufacturing engineers to compute the optimal wire electric discharge machining process parameters for obtaining minimum wire wear. A series of experiments have been conducted with WEDM on P/M cold worked tool steel based on Taguchi L₂₇ orthogonal array (OA). This methodology is capable of predicting the response parameter as a function of six different process parameters, i.e. pulse on time (ON), pulse off time (OFF), spark gap set voltage (SV), peak current (IP), wire tension (WT), water pressure (WP). The effect of process parameters on wire wear is evaluated by signal-to-noise (S/N) ratio. The optimum levels of process parameters are found to be at pulse on time (A1) = 108 μsec, pulse off time (B3) = 63 μsec, peak current (C1) = 11 amperes, spark gap set voltage (D1) = 18 volts.