Abstract
This paper presents a guide line for the design of ring-form electrode in electropolishing of external cylindrical surface on several die materials. The process can be continuously applied to the traditional turning, form rolling, extrusion or drawing. The electrodes travel along the axis of cylindrical surface of workpiece connected with continuous or pulse direct current. The controlled factors include the chemical composition and concentration of the electrolyte, the electrolyte temperature, the flow rate of electrolyte, and the initial gap width. The experimental parameters are die material electrical current rating and pulse period, rotational speed of workpiece, rotational speed of electrode, the electrode feed rate, and the electrode geometry. Thin ring and large inner taper angle are associated with large discharge space for the electrolytic products, thus the polishing is more effective. Adequate sharp inner edge radius of the ring electrode provides high current density leading to fast feed rate as well as good polishing. The partial-ring with small cross section and large inner radius is more advantageous. The polishing results with pulse direct current are slightly better than the continuous direct current. However, the use of pulse current raises the machining time and cost. The effects of the electrode design surpass the considerations of the electrical conditions and motion control of workpiece and electrode.