Influence of graphene reinforced sunflower oil on thermo-physical, tribological and machining characteristics of inconel 718

Owing to the extreme heat generated during Inconel 718 machining, the application of a minimum quantity lubrication (MQL) strategy is restricted to mild cutting conditions. By incorporating vegetable-based cutting oils reinforced by nanoparticles as possible additives, the effectiveness of MQL can be improved in high-speed machining. In this study, hybrid nano-green oils were developed by combining graphene nanoparticles in various volume concentrations with sunflower oil. Subsequently, dispersion stability, thermal conductivity, viscosity, and wetting angle of nano-green oils were measured. An MQL device is used to disperse the smallest amount of nano-green oils throughout the machining area. Later, the experimentally optimized graphene-based green oil is used for milling experiments. Furthermore, hard machining experiments were conducted with cutting speed of 80 m/min, feed rate of 0.2 mm/rev, and depth of cut of 0.5 mm under four different lubricating mediums: dry, flooded, sunflower oil, and 0.7% graphene reinforced sunflower oil. Comparative results show that 0.7% graphene reinforced sunflower oil performs better and reduces surface roughness by 49%, cutting force by 25%, cutting temperature by 31%, and tool wear by 20% as compared to dry machining environment. Finally, elemental analysis of cutting insert reports that adhesion is the major wear mechanism in all mediums.