Electrode form design of large holes of die material in ultrasonic electrochemical finishing

Abstract This paper uses ultrasonic energy to assist the dregs discharge in electrochemical finishing for the improvement of surface finish of large holes beyond traditional drilling, boring, rough turning, or extruding for die material during the polishing process. Six types of feeding electrodes and another six types of inserted electrodes are connected with both continuous and pulsed direct current in the ultrasonic electrochemical finishing. For inserted electrodes, a slant discharge flute on the plate with small edge rounding radius provides more sufficient discharge space, which is advantageous for polishing. A single plate electrode performs better than the double plate. The electrode of the single plate with borer shape edge and slant discharge flute shows the best polishing effect. For feeding electrodes, a smaller end radius of the borer tip produces more space for dregs discharge and better polishing. An electrode of single-side borer tip performs better than the double tips. The electrode with single-side half borer tip performs the best polishing effect in the current investigation. The average effect of the ultrasonic energy is advantageous than the pulsed current while the machining time needs not to be prolonged by the off-time. The geometry of the electrode contributes the most to the improvement of surface finish. Using the adequate electrode geometry as well as the ultrasonic aid, an effective and low-cost electrochemical finishing of large holes is presented.