Effective Form Design of Electrode in Electrochemical Smoothing of Holes

Abstract

This study discusses electropolishing of holes using feeding electrodes as well as inserted electrodes for several common die materials. Traditionally, the hole polishing of a die requires a sequence of complicated premachining operations or scarce manual skill. In the current experiment, eight types of electrode are used and supplied with both continuous and pulsed direct current and another eight types of electrode are fed into holes using continuous direct current. The design features of the electrodes are of major interest for the effective electrochemical of holes. The controlled factors include the diameter of the electrode as well as the chemical composition and the concentration of the electrolyte. The experimental parameters are current density, current rating, electrode design, die material, rotational speed and feedrate of the electrode. For inserted electrodes, an electrode with a helical discharge flute performs better than one without a flute or with a straight flute. Pulsed direct current can improve the polishing effect at the expense of increased machining time and cost. For feeding electrodes, an electrode of a borer type performs better than one with a cycle lap on the leading edge. It was also found that electrobrightening after reaming needs only a short time to make the hole bright, and electropolishing saves the need for reaming, making the total process shorter than for electrob-rightening.