Novel curved trajectory machining using VOEDM process – experimental study and statistical optimisation thereof

Abstract

ABSTRACT This paper presents a novel Variable Oscillating EDM process through a mechanism provided on the Z-axis numerical control EDM for machining the curvature channel. The specific trajectory is machined inside the oil hardening non-shrinking steel workpiece through the curved copper electrode. In order to execute the experiments, critical input machining parameters (sparking current, pulse on time, pulse off time, and swing sensitivity) and output process characteristics (Electrode wear rate and material removal rate) are selected. Taguchi experimental design (L9) is used to design the experiments. The pulse off time has a significant effect on VOEDM process characteristics. Analysis of variance is used to identify the significant contributions of selected parameters. It identifies the major contributing factor to be the pulse off time for EWR (50.33%) and MRR (34.78%). The machining parameters optimised using regression analysis adopting a forward selection method. Finally, confirmation runs are performed to evaluate the results of optimal combination of machining parameters with output characteristics. The average experimental values at optimum conditions for achieving minimum EWR and maximum MRR are 0.000194mm3/min and 0.000397mm3/min, respectively. Further, SEM was used for analysing the material behaviour of workpiece. The experimental results confirm the validity and sustainability of the VOEDM process.