PARAMETRIC INVESTIGATION OF NEAR DRY EDM

Abstract

Near dry Electrical discharge Machining (NDEDM) evolved out as the most promising process variant of EDM as providing with very good results in comparison to all other variants in terms of improved material removal rate (MRR) with improved surface roughness (SR) conditions with negligible tool wear rate posing approximately no threat to the environment and working operator. But there is a need to improve the significant response characteristics. For this purpose various experiments are being carried out on high speed tool steel (HSTS) M35 with tubular copper electrode by using the following dielectric mixtures of air with distilled water, air with glycerine, air with distilled water along with oxygen and, air with distilled water along with glycerine and then their comparison is being made by taking MRR and radial overcut as the response characteristics. The variable process parameter used for these experiments are pulse current, pulse on time, fluid flow rate and lift. The results have shown very best results for glycerine with very good MRR and comparably less radial overcut. The use of oxygen with air as dielectric along with distilled water gave quite good results for increasing MRR to three times comparably. The inner radial overcut generated was very less and consistent to be around 0.1mm.