Promotion of Fluid Lubrication in Wire Drawing

Abstract

One of the factors limiting the rate at which wire can be drawn through tungsten-carbide or diamond dies is the severe die wear which may occur at high speed. If true hydrodynamic (fluid-film) lubrication could be provided in the die, wear would probably be much reduced. It is suggested that this can be done by supplying oil to the entry of the die at a pressure comparable with the yield stress of the wire. The necessary pressure can be conveniently generated by causing the wire to approach the die through a tube of diameter slightly larger than the wire diameter, sealed on to the inlet side of the die. Experimental work shows that the friction in the die itself can then be so reduced that, even when the drag in the tube is allowed for, the total drawing force is less than with the existing method of soap lubrication; and tests with steel dies have shown large reductions in wear. A theory of the behaviour of the inlet tube and of temperature distribution in the system is included.