Critical review on ecological, economical and technological aspects of minimum quantity lubrication towards sustainable machining

To reduce the intensity of friction, wear, heat and cutting power throughout machining operations the conventional flood lubrication technique was practiced commonly on shop floor. Since cooling and lubrication action is mainly achieved through varieties of metal working fluids during flood cooling methodology utilizing large quantity of water that discharges contaminated effluents hence polluting the water, air and soil. Further, the excessive exposure and usage of fluids leads to unpleasant environment and uneconomical machining. Therefore the role of coolants is significant during the course of selection, application, handling and disposal activities. Also the wastage disposal of metal working fluids has become controversial due to undeviating environment protocols, strict government regulation and public awareness. Hence, the requirement to solve these problems is of utmost importance in present age of Industry 4.0 considering current scenario of water footprints, pollution levels and global warming impacts. So, to resolve these challenging situations, dry machining preferred by industries has uneconomical nature during processing of harder material. Consequently, the best solution to these issues probably has been achieved through minimum quantity lubrication assisted with biodegradable fluids. In present study, the various methodologies of cooling and lubrication employed during varieties of machining operations were critically analyzed and their potential towards sustainable machining was examined. The review results revealed that considerable advancements were reported in cooling and lubrication techniques and pointing towards economical, ecological and sustainable machining. Furthermore, the latest trends have reported that the application nano-fluids, ionic liquids, bio-degradable oil in cooling technologies as well as hybrid machining have strengthened and extended the utility of these techniques to machine varieties of harder materials at higher speed ranges in present era of industry 4.0.