6. Experimental Investigation and Finite Element Modelling of Electrical Discharge Machining Using Hollow Electrodes and Injection Flushing

Electrical discharge machining (EDM) is a non-contact machining process in which rapid electric discharges are used to remove material from a workpiece by melting and vaporisation. The need for components with intricate and difficult to manufacture features have increased drastically over the past few years in different fields of application. The objective of this work was to carry out experimental investigations on the machining of EN31 steel alloy by varying input parameters like peak current and pulse-on-time, with different tool electrodes using the injection flushing configuration, to compare the effect of electrodes on material removal rate, tool wear rate and surface roughness in drilling annular holes on the workpiece. Finite element modelling of the process was done using COMSOL Multiphysics to calculate the temperature distribution and the volume of the craters formed during sparking. The results obtained from the model are then compared with the experimental data and were found that they are complementing each other. Copper is a better electrode material for machining EN31 alloy steel to obtain better material removal rate with least tool wear rate.