Parametric study and multi-characteristic optimization of rotary turning process assisted by axial ultrasonic vibration

Abstract

Turning with rotary tool is a newly developed alternative of conventional turning process in which cutting edge of a round insert rotates about its axis, so that a continuously indexed cutting edge is fed into the cutting zone. In the present study an axial high-frequency vibration applied to rotary tool to improve machininability of AA7075 during orthogonal cutting. However, due to contribution of wide ranges of factors in vibratory-rotary truing process, selection of optimal parameter setting is a challenge that faced with this process. In the present work, an attempt was made to simultaneously minimize machining force (Fz) and surface roughness (Ra) through selection of optimal setting of cutting velocity, feed rate, tool rotary speed in rotary turning (RT) and vibratory-rotary turning (VRT) operations. Here, grey relational analysis (GRA) wasused to find optimal parameter setting in RT and VRT processes, separately. Then the obtained solutions were compared.Results indicated applying axial vibration to rotary tool turning significantly reduces both surface roughness and cutting force. From the optimization by GRA method, it was obtained that for both RT and VRToperations, setting of 4 m/min cutting velocity, 220 RPM tool rotary speed, 0.08 mm/rev feed rate and 0.3 mm depth of cut is most-optimal solutions that causes minimum Fz and Ra, simultaneously. Also, the VRT process had higher values of grey relational grade than RT process that implies outperformance of VRT with respect to RT process. The obtained results were then verified, compared and discussed based on mechanics of turning process.