Metalworking lubricants perform several functions. They protect or improve surface finish, provide corrosion protection, reduce frictional forces, cool the tooling, prevent metal pick-up on the tooling, and flush away the chips created in the machining operation.
To perform these functions they contain a complex blend of carrier, lubricity additives, corrosion inhibitors, biocides and antifoams.
The major component of a lubricant are the carrier, lubricity additives, and an emulsifier. Carriers are petroleum oils, water or solvents.
Their function is to provide cooling, act as a vehicle for the other additives, and flush away the chips. Water based lubricants are preferred in metal machining because water removes heat caused by friction and assists in metal removal twice as fast as oil.