Ultrasonic Pulsating current has three parameters: pulse on time, pulse off time, and peak current density which can be varied independently to achieve desired machining rate. By suitable choice of the above parameters, variations of electrolyte conductivity in the machining region could be reduced and high, instantaneous mass transport achieved even at low electrolyte flow rates. The appropriate selection of length and duty of pulse was essential to obtain the best surface quality. Experiments performed to study the effect of variation in pulse on time and pulse off time on surface quality indicated thatshort pulse on time and high pulse off time yield improved surface with less pitting (Rajurkar et al. 1999).
The experiments that were conducted maintained the same pulse on/off time while machining at low frequencies. The pulse off time was more than the pulse on time at high frequencies to enable the electrolyte to flush away the machining products which was in accordance with existing data. Figure shows plot of surface roughness versus pulse on and pulse off time.