This book contains how (a)experiments were carried out to analyze the effects of machining current on various machining criteria, like cutting speed, spark gap, surface finish and MRR for machining different electrode materials as work pieces, that is Graphite and Aluminum of 5 mm thickness and to decide the best suitable machining current to be used for machining. (b)effect of the work piece thickness on cutting speed, spark gap, surface roughness, MRR and machining current are investigated under optimal parametric settings of gap voltage, wire velocity and wire tension specially with reference to the materials under investigation, that is Graphite and Aluminum of thickness ranging from 5mm to 80mm. (c)finally the best parametric values of machining are arrived and henceforth mathematical correlations are developed using software and ANOVA was conducted for checking the fitness of the correlations. These may be useful for determining the discharge or cutting current required, cutting speed, spark gap and MRR for both the materials under investigation that is Graphite and Aluminum. (d)the machinability index for the materials under testing and other materials is evaluated.