The role of voltage pulse off-time in the electrodischarge machined AISI T1 high-speed steel

A transistorized pulse generator has been used to study the effect of changing the voltage pulse off-time, at constant values of pulse on-time, on the machining characteristics of electrodischarge machined AISI Tl high-speed steel. A copper electrode with positive polarity, kerosene dielectric, side flushing and a current setting of 31.2 A were used throughout all of the experiments. The results have shown that the metal removal rates are not very sensitive to off-time changes at a low pulse on-time corresponding to finish machining and show a higher sensitivity to these changes at higher on-times corresponding to intermediate and rough machining. Volumetric electrode wear has been found to be less with shorter off-times when finish machining but independent of the off-time when intermediate or rough machining. The values of the surface roughness of the machined specimens have been found to be independent of the off-time and direction of flushing, for all machining conditions.