Experimental investigation into lubrication properties and mechanism of vegetable-based CuO nanofluid in MQL grinding

Application of vegetable-based nanolubricants in machining operations has been promoted due to the environmental concerns and higher demand for better quality of machined parts. In this study, lubrication properties of copper oxide nanofluids in surface grinding of AISI 1045 hardened steel are investigated. These nanofluids were synthesized by submerged electro discharge process, exposed to ultrasonic agitation in the presence of Tween 20 as dispersant and sprayed in grinding position using minimum quantity lubrication system. The base fluid is an emulsion of canola oil and distilled water with vegetable oil acting as triglyceride agent. Convective heat transfer coefficients of different lubrication systems in grinding are measured using an innovative approach to better explore the cooling mechanisms involved in grinding process with or without the application of nanolubricants. The variation of grinding forces and sub-surface temperature of workpiece are recorded at different lubrication conditions. These parameters along with surface roughness, micro-hardness, and microscopic observations of ground surfaces are employed to evaluate the performance of synthesized nanofluids as lubricants in grinding. The results show that the synthesized nanofluids are effective in reducing the grinding forces and temperatures especially in extreme machining conditions. Better surface integrity of ground parts is observed in all grinding conditions through the application of CuO nanofluids as lubricant in minimum quantity lubrication system.