Influence of machining conditions on dry EDM with workpiece cooling of Inconel 625 alloy in the milling kinematics

Abstract

One potential eco-friendly variant of electro-discharge machining is dry electro-discharge machining (EDM), in which the liquid hydrocarbon–based dielectric is substituted with a gaseous medium. The primary challenge associated with dry EDM is the excessive dissipation of heat within the machining gap, which restricts its utilisation only to a microscale machining. Consequently, further modifications to the underlying mechanism of the process are being undertaken with the aim of efficient industrialising it on a larger scale. In the present study, a novel approach is proposed to enhance the efficiency of dry-EDM process while using carbon dioxide as a gaseous medium together with introducing additional external workpiece cooling with deionised water. A series of experiments were conducted to determinate the impact of external workpiece cooling with deionised water and the main machining parameters, namely pulse-on time and current intensity gas pressure, on the material removal rate, working electrode wear, and surface integrity of Inconel 625 during EDM in milling kinematics. The results demonstrated that, under the same machining parameters, the wear of the working electrode, the surface roughness, and the thickness of the recast layer were significantly reduced in the EDM with external workpiece cooling in comparison to the dry-EDM process without water cooling. Furthermore, the EDM with coolant exhibited superior performance in comparison to the dry-EDM process due to the fact that there were fewer changes in the surface morphology and chemical composition of the machined material.