The material removal mechanism and surface characteristics of Ti-6Al-4 V alloy processed by longitudinal-torsional ultrasonic-assisted grinding

Titanium alloys have excellent heavy-duty performance, but their processing and surface quality control are quite problematic. This problem can be resolved via the longitudinal-torsional ultrasonic-assisted grinding (LT-UVAG). In this study, the LT-UVAG removal mechanism and surface parameters of Ti-6Al-4 V titanium alloy were investigated. Based on the motion path analysis of a pair of abrasive grains of LT-UVAG, the material removal process and grinding chip formation mechanisms in Ti-6Al-4 V alloy were analyzed for different processing characteristics, and the coexistence of up- and down-grinding stages was revealed. The theoretical analysis was performed to assess the effect of processing parameters on surface quality, and the longitudinal ultrasonic amplitude was optimized. Besides, a surface topography simulation model of Ti-6Al-4 V, with account taken of Poisson’s effect, was proposed and realized via Matlab spreadsheet program. Finally, the experimental validation of the above findings was performed, proving that under LT-UVAG conditions, grinding chips were miniaturized, the surface roughness was reduced by 26%, and the surface adhesion was significantly weakened. Furthermore, LT-UVAG produced microtextures on the machined surface, which morphology was effectively predicted by the proposed surface model. The results obtained are considered instrumental in selecting the optimal ultrasonic amplitude for improving the machining quality and realizing controllable surface processing quality.