Impact of induction hardened workpiece hardness on EDM performance

The objective of this research work is to correlate the impact of thermally induced workpiece hardness with electric discharge machining (EDM) performances and establishment of the modified property responsible for the deviation in change in behavior of output responses in sinking electrical discharge machining process. The response surface methodology with central composite design approach was applied with four controllable input parameters such as pulse-on-time (T_on), pulse-off time (T_off), peak current (I_P), and gap voltage (V) for experimental comparative study. In this current analysis, material removal rate, tool wear rate, and energy density were chosen as the desired response variables. It was observed that change in hardness through induction thermal hardening process of the base alloy had a predominant effect on the change in output responses such as material removal rate, tool wear rate, and energy density with strong confirmation. The modified electrical property associated with enhanced workpiece hardness was primarily responsible for alteration in EDM process behaviors. This preliminary assessment for the deviation in the performance of the EDM process with respect to change in hardness will be quite useful for the control settings in the job shop production planning for processing and modifying properties of induction hardened alloy steels.