Towards sustainable machining: an experimental study of eco-friendly MQL and its impact on machinability and future opportunities

Abstract Enforcement of stricter environmental policies calls for alternative methods that could reduce the usage of cutting fluid during machining. Thus, dry machining and minimum quantity lubrication (MQL) machining are gaining practical importance. From this perspective, the development of new biodegradable MQL fluids and their performance assessment during machining is acquiring global attention. In this work, Jatropha crude oil (JCO) is chemically transformed into an epoxidized product and used as a MQL fluid. The turning experiments are conducted on Nimonic 80A under varying cutting speeds, and feed rates with constant depth of cut to examine the effects on machinability characteristics. The experiments are conducted under three different environments viz. dry, conventional minimum quantity lubrication (CMQL) and epoxidized minimum quantity lubrication (EMQL). The cutting force, tool flank wear, surface roughness and chip morphology are used as performance indicators. Regarding environmental concerns, the EMQL proved to be a viable substitute for CMQL as it demonstrated the lowest cutting force, tool wear and surface roughness. EMQL can reduce tool wear and surface roughness to the extent of about 54% and 22% as compared to the dry machining environment. The cutting force is reduced by about 13% and 34% by adopting CMQL and EMQL respectively even under the high feed (f = 0.45 mm min −1 ) condition. The sustainability assessment model developed using the Pugh matrix environmental approach disclosed EMQL system helps in attaining the desired machinability qualities while offering environmental friendliness and cleaner production.