Surface morphology evaluation of multi-angle 2D ultrasonic vibration integrated with nanofluid minimum quantity lubrication grinding

Nanofluid minimum quantity lubrication (NMQL) is an emerging cleaner and sustainable technique. However, the effective immersion of nanofluids in the grinding zone in NMQL grinding limits the extensive application of this technique. Ultrasonic vibration can exert a pumping effect that injects nanofluids into the interface between the grinding wheel and workpiece. Furthermore, technique integration benefits the infiltration state transition of micro-droplets. However, evaluation of the coupling effect and surface morphology of multi-angle 2D ultrasonic vibration integrated with NMQL has rarely been performed. This study aims to address these research limitations. A kinematics model was developed, and the grain and workpiece relative motion trails in 2D ultrasonic vibration-assisted grinding (UVAG) were simulated at different resultant vibration angles (theta). The grain's cutting characteristics were then analyzed and found to be conducive to the full infiltration of nanofluids into the grinding zone. Moreover, the surface characterization of multi-angle 2D UVAG coupled with NMQL was evaluated experimentally. Results showed that the optimal theta was achieved at 45 degrees due to the differential cutting action of the follow-up grain. NMQL obtained a better result than flooding at the same theta. When the gain effect of the coupling techniques was reflected in surface roughness, the Ra value decreased by 19.5 % (compared with UVAG) and 39.9 % (compared with NMQL). The autocorrelation function curves presented periodic and continuous local oscillations under the grinding conditions of 2D UVAG with theta = 45 degrees and theta = 135 degrees.