Effect of power excitation form on machining characteristics of TC4 titanium alloy by SEAM-ECM combined machining.

By introducing a high concentration of electrolyte into the working medium of conventional short electric arc machining (SEAM), we have realized the removal of surface defects of SEAM using electrochemical machining (ECM) during the discharge of SEAM. This process is called short electric arc-electrochemical (SEAM-ECM) combined machining. The forms of power excitation mainly use pulsed and constant voltage DC. Therefore, this research first reveals the arc-breaking and action mechanism of SEAM-ECM combined machining under two excitation forms by single-pulse simulation and experiment. The results show that DC excited arc-breaking is an adaptive arc-breaking over the discharge gap; the intensity and duration of ECM action of DC excitation are higher than that of pulsed excitation; at the same current strength, the arc-breaking time of DC excitation is about three times more than that of pulsed excitation (duty cycle of 55%). In addition, continuous discharge experiments are conducted to verify the machining effect of SEAM-ECM combined machining. The results show that DC excitation tends to form a continuous arc during machining, aggravating copper electrode loss and reducing the workpiece's dimensional accuracy and the material removal rate. The concentrated discharge energy also produces deeper discharge pits, making the workpiece surface rougher relative to the pulsed excitation. The machining differences between the two excitation methods at different voltages are compared, showing that a balance exists between SEAM and ECM under suitable machining conditions. [ABSTRACT FROM AUTHOR]