Comparative performance analysis of nano-enhanced liquid lubricants under minimum quantity lubrication and flood lubrication in machining

This work compares the performance of nano-enhanced lubricants under Minimum Quantity Lubrication (MQL) and flood machining. Environmentally benign base oils like coconut, mahua, castor and groundnut oils were chosen and nano-enhanced with single and hybrid mixtures of aluminium oxide (Al₂O₃), titanium dioxide (TiO₂), and graphite nanoparticles. The effectiveness of the machining process was assessed considering the surface roughness, tool wear, coefficient of friction and temperature. The experimental findings show that nano-enhanced lubricants in MQL machining conditions enhance tribological properties better than flood lubrication. Nanoparticles improve the lubrication performance through mechanisms such as the formation of tribo-films, rolling effect and enhanced thermal conductivity. The use of hybrid nanoparticles shows a combined effect, which leads to significant improvement in surface finish, tool life, and friction coefficient. While flood machining offers better cooling due to the increased use of fluid, it suffers from low nanoparticle concentration and poor penetration into the tool–chip interface. The best MQL performance was observed with a hybrid nanoparticle (Al₂O₃, TiO₂, and graphite) combination using coconut oil. The research shows that nano-improved MQL is an effective and sustainable form of machining for improved machining performance and environmental benefits compared with traditional flood machining.