Influence of minimal quantity lubrication (MQL) technique in achining evolution: A review and applications

Abstract

Metal working fluids (MWFs) are one of the types of lubricants, which are extensively used in machining operations. Most of the MWFs are mineral oil based fluids. Due to their advantages, the consumption of MWFs is increasing in machining industry. Mineral, synthetic and semi-synthetic MWFs involve in the ecological cycle with air, soil and water and their toxicity effects damages the ecosystem. Vegetable oil lubricants are potential substitutes for mineral oil not only because they are renewable raw materials but also because they are biodegradable and non-toxic. Currently, there is a wide-scale evaluation of the use of metal working fluids (MWFs) in machining. Industries are looking for ways to reduce the amount of lubricants in metal removing operations due to the ecological and economical aspects. By implementing near-dry machining or a minimal quantity of lubrication (MQL), MWFs consumption can be reduced. The MQL technique involves the application of a small quantity of lubricant dispensed to the tool–work piece interface by compressed air flow. This paper gives a review on the mechanical performance of minimum quantity lubrication compared to completely dry and flood lubrication for various machining operations.