Specific energy and surface roughness of minimum quantity lubrication grinding Ni-based alloy with mixed vegetable oil-based nanofluids

Vegetable oil is a low toxic, excellent biodegradable and renewable energy source used as an ideal lubricating base oil in machining. Castor oil exhibits good lubrication performance but poor mobility, which limits its application especially in precision grinding. The main objective of the work presented to obtain optimal mixed vegetable based-oil and optimal nanoparticles adding concentration in grinding Ni-based alloy with minimum quantity lubrication. An experimental investigation is carried out first to study the different vegetable oils with excellent mobility mixed with castor oil. The lubrication property of the oil was evaluated in terms of grinding force, force ratio, specific grinding energy, and surface roughness. Based on the test conditions, it is found that soybean/castor mixed oil obtained the optimal results (μ= 0.379, U = 83.27 J/mm3 and Ra = 0.325 μm) and lubricating effect compared with castor oil and other mixed base oils. To further explore the lubricating capability of soybean/castor mixed oil, MoS2 nanoparticles which have excellent lubricating property were added into the soybean/castor mixed oil to prepare different concentrations nanofluids. From the present study, it can be concluded that 8% mass fraction of the oil mixture should be added to obtain the optimal machining results, with the lowest force ratio (0.329), specific energy (58.60 J/mm3), and average grinding temperature (182.6 °C). Meanwhile, better surface microtopography of ground parts and grinding debris morphologies were also observed for the machining conditions.