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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]

In accordance with the lubricating performance of nanofluid minimum quantity lubrication (N-MQL) grinding with different vegetable oils as the base oil in previous research, cooling performance was explored with a new method. Friction coefficient, specific friction energy, total heat flow density, and grinding peak temperature were used as evaluation parameters. The influence of the physical properties (viscosity, surface tension) of vegetable oils on the cooling effect was analyzed comprehensively. For the new method, a new ploughing force model and a friction force model were established, and cutting force and ploughing force were calculated theoretically. Afterward, friction force was obtained according to the theoretical model and experimental results and was used to calculate the evaluation parameters. The vegetable oil nanofluids showed better cooling performance than mineral oil because of their lubrication-favorable fatty acid molecules. Furthermore, the mechanism of the effect of nanofluid viscosity and surface tension on cooling performance was explored. Vegetable oil with a low viscosity and surface tension showed good cooling performance and that with a high viscosity and surface tension showed good lubrication performance. As a result, palm oil nanofluid with a high viscosity and surface tension achieved the lowest friction coefficient (0.258), specific friction energy (27.09 J/mm 3 ), and grinding peak temperature (123.8 °C) and exhibited better grinding performance than the others. [ABSTRACT FROM AUTHOR]