Design of effective plate-shape electrode in ultrasonic electrochemical finishing

Abstract

This research provides a process of ultrasonic aided electrochemical finishing using a low-cost electrode with high efficiency. It requires no expensive special-purpose equipment or high material removal as the conventional ECM does. It offers fast improvement of the surface roughness of the workpiece and is a new area in ECM. In the current study, the electrochemical finishing is classified into electrochemical smoothing and electrobrightening, higher electrical current is not required when an effective plate-shape electrode is used to reduce the response area. This process can be used for various turning operations including profiling, form turning, and flute and thread cutting. Through simple equipment attachment, electrochemical smoothing and electrobrightening can follow the cutting on the same machine and chuck. The controlled factors include the chemical composition and concentration of the electrolyte, the initial gap width, and the flow rate of electrolyte. The experimental parameters are the current density, rotational speed of the workpiece, on/off period of pulsed current, frequency and power level of ultrasonics, and the electrode geometry. Smaller end radius and smaller angle of declination are associated with higher current density and provides larger discharge space and better polishing effect. The electrode of inclined plane with slant discharge flute performs the best. The average effect of the ultrasonics is better than the pulsed current while the machining time needs not to be prolonged by the off-time. It was also found that electrobrightening after precise turning needs quite a short time to make the workpiece smoothing and bright, and the electrochemical smoothing saves the need for precise turning, making the total process time less than the electrobrightening.