Milling force and surface morphology of 45 steel under different Al2O3 nanofluid concentrations

Nanofluid minimum quantity lubrication (NMQL) is a resource-saving, environment-friendly, and efficient green processing technology. Cottonseed oil can form a strong lubricating film owing to its abundant saturated fatty acids and monounsaturated fatty acids, which have excellent lubricating properties. The physical and chemical properties of nanofluids change when Al2O3 nanoparticles are added. However, the effects of cottonseed oil-based Al2O3 nanofluid concentrations on the milling force and workpiece surface quality remain unclear. To address this limitation, 45 steel was used to conduct NMQL milling experiments of cottonseed oil-based Al2O3 nanofluids with different mass fractions. Results showed that the minimum milling force was obtained at a concentration of 0.2 wt% (F-x = 58 N, F-y = 12 N). The minimum surface roughness value (R-a = 1.009 mu m, RSm = 0.136 mm) was obtained at a mass concentration of 0.5 wt%, and the micromorphology of the workpiece/chip was optimal.