Optimization of Lubrication Strategies in Drilling Process: The Impact of Nanofluids and Nozzle Design on Temperature Rise and Surface Roughness

This study investigates the effect of various lubrication strategies on temperature rise and surface roughness during the drilling process of CK45 steel. Key minimum quantity lubrication (MQL) parameters, including nozzle geometry, angle, distance and lubrication type, were evaluated using the response surface methodology (RSM) approach. Results demonstrated that nanofluid minimum quantity lubrication (NFMQL) with graphene/water nanofluid significantly reduced temperature and surface roughness by 43% and 55%, respectively, compared to flood lubrication, and by 57% and 62% compared to dry conditions. Among the tested lubricants, graphene/water nanofluid achieved the lowest temperature, while palm oil resulted in the highest. Nozzle geometry proved to be the most influential parameter, with rectangular cross-section nozzles providing a 16–20% reduction in temperature and a 30–43% improvement in surface roughness compared to circular and square nozzles. Most effective lubrication conditions were identified as a nozzle angle of 30[Formula: see text] and a distance of 50 mm, enabling improved lubrication while preventing chip accumulation on the nozzle. SEM analysis confirmed that dry conditions resulted in higher temperatures, leading to poorer surface quality, while NFMQL with graphene nanofluid minimized fine cracks and improved surface finish. Overall, this study highlights the superior performance of graphene nanofluid and improved nozzle designs in enhancing lubrication efficiency, resulting in reduced manufacturing costs.