Metal cutting lubricants can be defined as specially formulated oils, liquids, waxes and fluids that are used to cool and/or lubricate metal workpieces when they are being machined, ground, milled, etc.
Lubricants perform several key functions during harsh metal working operations. One is cooling. Lubricants absorb heat from the machining process, and transport the heat, chips, and debris by flowing away from the work area. Another is lubrication. The more lubrication delivered to the work area, the more effective the cut, and the more control you have over the size and finish of the work. The ideal lubricant is one that delivers the best cooling and the most lubricity for the cost.