Solid lubricants in machining

This article presents a review of solid lubricants application in different machining processes such as grinding, milling, drilling, and turning. Of late, several reasons have led to the increased usage of solid lubricants in machining. The heat generated in the cutting zone during machining is critical in deciding the workpiece quality. Although cutting fluids are widely employed to carry away the heat in machining, their usage poses threat to ecology and the health of workers. Hence, there arises a need to identify eco-friendly and user-friendly alternatives to conventional cutting fluids. Modern tribology has facilitated the use of solid lubricants as an alternative to cutting fluids in machining. Graphite, calcium fluoride, molybdenum disulphide, and boric acid are the general solid lubricants used in machining. Process performance is improved with the application of solid lubricants in machining. By reducing coefficient of friction, cutting forces and tool wear are reduced in machining with solid lubricants. Reduction in cutting forces results in lower specific energy requirement and thus reduces production cost. Surface quality of the machined workpiece is also improved with solid lubricants.