Metal Machining With High-Pressure Water-Jet Cooling Assistance—A New Possibility

Abstract

Metal machining is one of the fundamental manufacturing processes. The principal cost of shaping metal parts is generated both in the work involved in shearing metal from the original stock, at the area where the chips are formed, and also in the work required to overcome the high frictional forces that exist between the chip and rake face. Current techniques for the lubrication and cooling of this area are not very effective, resulting in a machining cost which is much higher than need be. A more efficient lubricooling effect can be achieved by the use of a high-pressure water jet directed into the tool/chip interface. The study of this idea was prompted by results achieved in the 1950’s, but now extended to much higher jet injection pressures (up to 280 MPa). The emphasis of this article is on the comparison of the coefficient of friction at the tool/rake interface for conventional and high-pressure jet cooling and also on reporting some practical results. Evaluation of these results indicates both a significant gain in the material removal rate as well as an improvement in the chip shape. The results are for a UNS 1020 steel—a representative of the poorly machinable materials.