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Considering the poor lubricating effect of cryogenic air (CA) and inadequate cooling ability of nanofluid minimum quantity lubrication (NMQL), this work proposes a new manufacturing technique cryogenic air nanofluid minimum quantity lubrication (CNMQL). A heat transfer coefficient and a finite difference model under different grinding conditions were established based on the theory of boiling heat transfer and conduction. The temperature field in the grinding zone under different cooling conditions was simulated. Results showed that CNMQL exerts the optimal cooling effect, followed by CA and NMQL. On the basis of model simulation, experimental verification of the surface grinding temperature field under cooling conditions of CA, MQL, and CNMQL was conducted with Ti-6Al-4V as the workpiece material. Simultaneously, CNMQL exhibits the smallest specific tangential and normal grinding forces (2.17 and 2.66 N/mm, respectively). Further, the lowest grinding temperature (155.9 °C) was also obtained, which verified the excellent cooling and heat transfer capabilities of CNMQL grinding. Furthermore, the experimental results were in agreement with theoretical analysis, thereby validating the accuracy of the theoretical model. [ABSTRACT FROM AUTHOR]

The present research investigated the lubrication performances of AlO/SiC nanofluid minimum-quantity lubrication (MQL) grinding in accordance with recent technologies used in conducting minimum-quantity lubrication grinding with nanofluids. The mean grain size of the AlO and SiC nanoparticles (NPs) was set to 50 nm, and the difficult grinding Ni-based alloy was used as the workpiece material in the experiment. Grinding force was measure by using a three-component dynamometer and then used to calculate grinding force ratio ( R). Workpiece surface roughness was measured by a roughness tester. Five groups of NPs were mixed with synthetic lipids at a mass fraction of 6 %. The lipids were then used as the grinding fluid for the nanofluid MQL grinding. Results showed that, compared with pure SiC NPs, pure AlO NPs obtained lower R = 0.3, lower specific grinding energy ( U = 75.93 J/mm), and lower surface roughness ( Ra = 0.386 μm), indicating better lubrication performance. The mixed NP consisting of AlO and SiC NPs achieved even lower R and surface roughness than pure NPs because of the 'physical synergistic effect.' The optimal ratio of the effect of mixed NPs was explored based on this finding. The AlO/SiC (2:1) mixed NPs obtained the smallest R = 0.28 and specific grinding energy ( U = 60.68 J/mm), thus indicating the best lubrication performance. Therefore, 2:1 is the optimal ratio for mixed NPs. [ABSTRACT FROM AUTHOR]