Study of Dry EDM with Oxygen-Mixed and Cryogenic Cooling Approaches

Dry electrical discharge machining (EDM) is a technology that has the potential to replace conventional liquid based EDM, owing to its low tool electrode wear, thin recast layer, and environmental friendliness. However, at present major challenges of dry EDM are found in its material removal rate (MRR) and an unsatisfactory surface quality that results from debris reattachment on the EDMed surface. To improve the MRR in dry EDM, two methods are proposed in this work. First, based on an analysis of the oxygen EDM mechanism, a dry EDM approach with an oxygen gas mixture is proposed, and we perform experiments to validate the analysis. Second, dry EDM on cryogenically cooled workpieces is considered, and we describe the accompanying experiments. The experimental results show an increase in the MRR for both the oxygen-mixed EDM and the cryogenically cooled workpiece technique, along with a decrease in the surface roughness value (Ra) for the latter. These results verify the feasibility of the proposed methods in improving dry EDM performance.