Investigation on surface roughness in axial ultrasonic vibration–assisted milling of in situ TiB2/7050Al MMCs

The surface roughness is one of the important parameters of surface quality evaluation. In the field of aerospace and industry, many attempts have been made to reduce the roughness of machined surface and improve the performance of parts. An advanced manufacture technique, ultrasonic vibration–assisted milling, can reduce the surface roughness, which is widely used to cut the materials that are difficult to machine. In this work, the theory of the machined surface generation is analyzed and the effect of cutting parameters and the ultrasonic vibration on the machined surface is investigated by ultrasonic vibration–assisted milling of in situ TiB2 particle–reinforced aluminum matrix composite. Firstly, the motion trajectory of cutting tool and machined surface topography generation is analyzed theoretically. Then, theoretical model of the number of vibration per cutting arc length and the transient angle is built to analyze the generation of the surface topography. Finally, experiments with and without ultrasonic vibration are carried out for the theoretical analysis of the machined surface generation and the surface roughness. The results show that regular micro-dimples are produced on the machined surface due to the addition of ultrasonic vibration and the theoretical model could be applied to explain the influence of ultrasonic vibration on the surface topography and roughness. Besides, in this study, the assistance of ultrasonic vibration can improve the surface quality in certain cutting conditions of cutting speed below 65.94 m/min and the vibration frequency of 20 kHz.