An investigation on surface integrity in EDM process with a copper tungsten electrode

One of the most important non-conventional machining methods is Electrical Discharge Machining (EDM). The present study performs the EDM process with copper tungsten electrode of diameter 2 mm to establish the influence of the EDM parameters on various aspects of the surface integrity of AISI 4340 steel. The residual stress induced by the EDM process is measured using the X-rays diffraction method. The experimental results reveal that the values of material removal rate (MRR), surface roughness (SR), and induced residual stress tend to increase at higher values of pulse current and pulse-on duration. However, for extended pulse-on duration, it is noted that the MRR, SR, and surface crack density all decrease. A smaller pulse current (i.e. 1A) tends to increase the surface crack density, while a prolonged pulse-on duration (i.e. 30 mu s) widens the opening degree of the surface crack, thereby reducing the surface crack density. It is determined that the residual stress can be controlled effectively by specifying an appropriate pulse-on duration. (C) 2016 The Authors. Published by Elsevier B.V.