Abstract
The current study discusses the improvement of surface finish of enlarge hole wall surface beyond traditional rough boring by electrochemical smoothing using different types of feeding electrodes. Higher electrical current is not required when the design electrode is used to reduce the response area for hole. In the experiment, six types of electrode are used with the application of continuous direct current and axial electrode feed. The controlled factors include the chemical composition and the concentration of the electrolyte, and the diameter of the electrode. The parameters are current rating, electrode geometry, die material, electrode rotational speed and feed rate. It was found that the electrobrightening after precise turning requires quit short working time, while the electrochemical smoothing saves the need for reaming or precise turning, thus makes the total cycle time less than electrobrightening. Smaller end radius of borer tip is associated with higher current density and provides faster feed rate and better polishing effect. A borer type electrode with small inclined angle toward to the cylinder provides more sufficient discharge space, which is advantageous for polishing. The electrode of oneside borer tip performs the best polishing effect in the current investigation.