Surface microstructure of titanium alloy thin-walled parts at ultrasonic vibration-assisted milling

Milling of the titanium alloy thin-walled workpiece is a critical challenging task and the machining vibration is a major effect on the accuracy of the final part due to difficult machining properties and low stiffness. The common milling (CM) is very hard for titanium alloy thin-walled parts to get high-quality machined surface microstructure, so finding an effective way of processing to obtain better surface microstructure is particularly important. In this article, the longitudinal-torsional composite ultrasonic vibration-assisted milling (LTCUVM) is proposed to overcome the problems of the common milling. The cutting method of the high-frequency vibration separation of a workpiece and the tool reduces an average cutting force. Thereby suppressing the tool relieving and further providing a good machined surface. In this study, firstly, the kinematic model of LTCUVM was established and the variations of the movement of the cutting edge flank with the spindle speed change were analyzed. Then the finite element model (FEM) of the two processing methods was developed and significant differences between the CM and LTCUVM in the micro-milling were revealed. Further, related experiments were designed and conducted. Finally, the experimental analysis showed that the LTCUVM effectively reduced an average cutting force, and further reduced surface roughness and height of chatter marks compared to the CM with the same processing parameters.