Effect of grinding wheel ultrasonic vibration on chip formation in surface grinding of Inconel 718

Abstract

Understanding the chip formation is one of most important issues in controlling the grinding wheel performance or the work surface finish in grinding process. This article discusses the effects of the ultrasonic vibration and peripheral speed of grinding wheel on the chip size and geometry in ultrasonic assisted grinding (UAG) of Inconel 718 with an electroplated cBN grinding wheel. Firstly, scanning electron microscopic (SEM) observations were performed on the chips formed at different vibration amplitudes and wheel peripheral speeds. The obtained 3D SEM images were used to determine the length and cross-section area of chips. Then, the geometries of chips were observed with SEM. The obtained results demonstrated that (1) chip size and geometry were distinctly affected by the ultrasonic vibration of grinding wheel but hardly by the wheel peripheral speed, e.g., the cross-section area of chips became smaller by 64.3 % and the length decreased by 36.3 %, respectively, once the ultrasonic vibration with an amplitude of Ap-p = 9.4 μm has been imposed to the grinding wheel; (2) the UAG is potentially avoiding the formation of shear chips and prefers the flow chips, especially at larger amplitude; (3) little changes were found on the chip geometry as the wheel peripheral speed increased in UAG; (4) the change in the chip size and geometry caused by the ultrasonic vibration was supposed to be owing to the ultrasonic lubrication and the vibration in the rake angle of grain cutting edge.