Experimental Investigation into Dry Electric Discharge Machining of Inconel 800

Abstract

Electric Discharge Machining (EDM) represents an unconventional machining technique employed to shape intricate forms in all conductive materials, regardless of their hardness. The use of dielectric liquid necessitates a sophisticated maintenance system within the EDM process. The resulting waste from the dielectric substance proves highly hazardous and poses significant disposal challenges. Additionally, the breakdown of the dielectric fluid generates toxic fumes, thus contributing to health risks. These limitations can be significantly eliminated through the employment of Dry Electrical Discharge Machining. In the Dry EDM approach, a gaseous medium is utilized in lieu of a liquid as the dielectric material. The study encompassed a range of input process parameters, including Electrode inner diameter (EID), Discharge current (I_d), pulse on time (T_ON), Gap voltage (V_g), Pulse off time (T_OFF), Tool rotation (N), Air Flow Rate (AFR) (specific to the Dry EDM process). A substantial Material Removal Rate (MRR) is accomplished in the Conventional EDM technique, in contrast to the Dry EDM method. In the Dry EDM process, a significantly superior MRR is attained with higher current values. Increased quantities of globules were noticed on the surface machined under the Conventional EDM procedure at EID 2 mm, I = 16A, V_g= 40V, T_ON= 90µs, TOFF =30µs RPM = 240 N machining conditions. The workpiece machined by the Dry EDM at 2mmI = 12A, V_g= 50 V, T_ON= 120µs, TOFF =15µs, RPM = 140N, AFR=20 l/min displayed an improved surface quality with fewer cracks. From EDS images, it was observed that the transfer of copper from the tool electrode to the workpiece is minimal in the Dry EDM process. However, when the air flow rate is increased from 15 l/min to 25 l/min, and RPM of electrode is increased from 140N to 240 N the migration of copper is significantly decreased. newline