Influence of machining parameters on the surface integrity in small-hole electrical discharge machining

This study investigates the effects of electro-discharge parameters on the surface integrity in small-hole drilling. Discharge current, pulse on-time and pulse off-time were chosen as variable parameters. The gap voltage, dielectric flushing pressure, electrode rotation, electrode polarity and capacitance were taken as constant. Material removal rate, surface roughness, average white layer thickness, overcut and taper were taken as outputs for this study. Experiments were performed on DIN 1.2080 (X210Cr12) cold working tool steel, and null 2 mm single-hole brass electrodes were used. The experimental results indicate that a compromise solution is required in selection of the electrical discharge machining parameters (i.e. discharge current, pulse on-time and pulse off-time) to maintain machining stability (melting-evaporation and removal of debris). As the stability is maintained during the process, dimensional accuracy increases and a better finish can be obtained with a reasonable machining time.