Enhancing surface morphology of machined SKD61 die steel in EDM process using DEAR approach based multi criteria decision making

The dies and molds made up of higher strength materials with complex shape can be easily machined using unconventional machining processes. The surface roughness and machining productivity during roughing phase has a very significant effect on increasing the efficiency of electrical discharge machining process. The optimization approach can enhance the mechanism of the machining process. In the present study, data envelopment analysis based ranking method was utilized to apply the multi criteria decision making in the process on machining SKD61 die steel. The influence of the input process factors such as voltage, pulse current and pulse-on-time were considered as input indicators in electrical discharge machining process. The material removal rate and surface roughness were selected as performance measures under rough mode to enhance the machinability in the process. From the experimental study, it was found that material removal rate and surface roughness were significantly improved under the optimal process parameter combinations of voltage (90 V), current (10 A) and pulse-on-time (100 µs). The optimal combination could produce 5% higher material removal rate with better surface finish. The surface quality of the surface layer can be improved under optimal parameters with lower white layer thickness owing to its importance on evaluating spark energy.