Study on Ultrasonic Assisted Electrochemical Drill-Grinding of Superalloy

Electrochemical grinding (ECG) technique composed of electrochemical machining (ECM) and mechanical grinding is a proper method for machining of difficult-to-cut alloys. This paper presents a new ultrasonic assisted electrochemical drill-grinding (UAECDG) technique which combines electrochemical drilling, mechanical grinding, and ultrasonic vibration to fabricating high-quality small holes on superalloy. By applying ultrasonic vibration to high-speed rotating electrode in ECG, machining stability, efficiency, and surface quality can be obviously improved. Firstly, the electrochemical passive behavior of superalloy is studied, the mathematical model and simulation of gap electric field are established. Then, several experiments are conducted to investigate the influence of applied voltage, feed rate and ultrasonic amplitude on the machining quality. The balance of material removal between electrochemical reaction and mechanical grinding is achieved by optimizing the machining parameters. It reveals that the surface quality as well as machining stability and efficiency can be significantly improved by applying rotating ultrasonic vibration to the ECG process. Finally, several small holes of high quality have been machined successfully along with surface roughness of hole sidewall decreases from Ra 0.99 μm to Ra 0.14 μm by UAECDG.