Performance assessment of reinforced nanofluid with surface-active agent for machinability improvement

The machining industry’s current trend is to increase machinability attributes and process performance so that nanofluid can be the right choice for the achievement. Two critical factors are evaluated to improve machining efficiency, including cooling-lubrication parameters and cutting fluid types. Therefore, in the present work, the main focus is on reinforcing the cutting fluid (nanofluid) and its injection technique to obtain optimal conditions. The results showed that since the nanoparticles had a high area-to-volume ratio, by passing time, their adherence inclination to each other was enhanced and immense pile was created. Therefore, it was swiftly deposited and a low volume nanofluid was produced. In other words, the single-phase nanofluid became into a two-phase fluid and two regions including nanoparticles and low volume nanofluid was attained. This event led to decline the nanoparticles transmitted through the cutting fluid that caused to decrease surface integrity and intensify tool wear. This phenomenon thoroughly confirmed by scanning electron microscope images and energy-dispersive X-ray spectroscopy analysis. Hence, surface-active agent (surfactant) were added to the nanofluid as a new additive, which resulted in significant stability in the nanoparticles’ buoyancy. Surface roughness and cutting force experiments indicated that the surfactant significantly reduced the removed regions on the workpiece surface and improved the surface roughness by 13% and 34% and cutting force by 14% and 2% compared with non-surfactant nanofluid and conventional cutting fluid. This improvement reached its maximum through the green technique of minimum quantity lubrication (MQL), which led to a more detailed study of MQL parameters and the optimal conditions in the present work. According to the experiments, the optimal surface quality, tool wear, and cutting force values were achieved at the flow rate, injection pressure, and tool-nozzle gap of 300 ml/h, 6 bar, and 3 cm.