Conventional theories about metalworking fluids state that they react chemically with the surfaces of metal workpieces during the short time that the two are in contact. These reactions supposedly form metal chlorinate, metal sulfide or metal phosphor layers that are more easily removed by the machine tool.
Researchers at a German supplier of metalworking fluids challenged that model recently, contending that, in most metalworking operations, the fluid and part are not in contact long enough for the complex reactions necessary to form these layers. In a January presentation at the OilDoc conference in Rosenheim, Germany, Wisura GmbH Research and Development Director Joachim Schulz proposed a new theory based instead on the premise that additives adsorb to workpiece surfaces. The new theory, he said, will lead to new approaches to formulating metalworking fluids.