Finite element modelling for electrical discharge machining of Ti-6Al-4V alloy and multi-objective optimisation using response surface modelling.

Electrical discharge machining (EDM) is a non-traditional precision machining method that thermally erodes hard materials and complicated geometries with excellent accuracy, but it also creates residual stress and fractures. Finite element modelling (FEM) was performed for an axially symmetric two-dimensional model of the EDM method, taking into account plausible factors such as Gaussian heat flux distribution, thermally sensitive material properties, the proportion of heat distribution to the workpiece, plasma flushing efficiency (PFE), and so on, to assess the consequence of process variables on the temperature field during the heating stage, and then material removal rate (MRR) and residual stresses. Utilising the response surface modelling (RSM) approach, multi-objective optimisation was performed to maximise the MRR and minimise tensile residual stresses, and an optimum solution was found by assigning equal weightage to all objective functions.