INVESTIGATION OF HOLE PROFILES IN DEEP MICRO-HOLE DRILLING OF AISI 420 STAINLESS STEEL USING POWDER-MIXED DIELECTRIC FLUIDS

A series of experiments were carried out to drill deep micro-holes, using Electrical Discharge Machining (EDM) with different concentrations of carbon powder/dielectric fluid mixture into, and varying machining parameters such as elecrode rotation speed and dielectric fluid spray pressure. Four dielectric fluid concentrations, three electrode rotation speeds, and three dielectric fluid spray pressure settings were tested; the resulting holes were investigated with respect to their average radial overcut and surface roughness (R-a) values. Study results indicate that as carbon powder concentrations, dielectric fluid spray pressure and electrode rotation speeds are increased, ARO values increased while R-a values are observed to decrease. It was determined that improvements in R-a and ARO values may be attained by the right configuration of machining parameters and the selection of the appropriate mixtures of carbon powder with dielectric fluid.