Effects of Graphite and Boron Carbide Powders Mixed into Dielectric Fluid on Electrical Discharge Machining of SKD 11 Tool Steel

Abstract

This paper investigates the effects on the electrical discharge machining (EDM) characteristics of SKD 11 cold work tool steel when adding graphite (Gr) and boron carbide (B4C) powder to the dielectric fluid. The introduction of different concentrations of powders into the dielectric fluid modified the results of the machining process. This was then compared with the results from normal machining conditions. This study examined the dimension of the machined hole, material removal rate (MRR), electrode wear rate (EWR), and surface roughness (SR). The results obtained from this study indicate the powder concentrations in the dielectric fluid had an obvious effect on the machining characteristics. The MRR and EWR values increased when both the Gr and B4C powders were increased. However, the surface roughness of the workpiece only increased when the Gr concentration was increased. In contrast, the addition of B4C powder resulted in a significant decrease in the roughness of the workpiece surface. In conclusion, the addition of Gr at a concentration of 2 g/l produced better machining characteristics than those under normal machining conditions. MRR was increased by 22.68%, and the EWR and SR were decreased by 2.85 and 17.18%, respectively.