Strip drawing experiments with a die-less reduction unit using polymer of “eva” as the pressure medium

Die-less drawing, introduced in connection with wire drawing (M. S. J. Hashmi, G. R. Symmons and H. Parvinmehr, J. Mech. Engng Sci. 24, 1–4 (1982)) is a process in which reduction in the wire size is achieved by hydrodynamic action. In this system, the conventional die is replaced by a reduction unit of stepped bore geometry. Polymer melts are used as the pressure medium, which, when dragged through the unit by pulling the wire, give rise to drag force and hydrodynamic pressure. The combined effect of these forces cause plastic deformation in the wire. The technique has also been applied to strip drawing (A. H. Memon, G. R. Symmons, M. S. J. Hashmi and R. Crampton, Proc. Inst. Mech. Engng Part E, J. Process Mech. Engng 203, 57–65) using polyethylene WVG 23 as the pressure medium. In the present study, polyethyl vinyl acetate has been used as the pressure medium in order to investigate the effect of polymer rheology on the process. Experimental results are presented in this paper, which show that this polymer causes larger reductions in width compared to polyethylene WVG 23. The results also indicate that a reduction in area of the strip in excess of 12% could be achieved in a single pass using this system. These experimental results show a close agreement to theoretical results previously published (A. H. Memon, G. R. Symmons, M. S. J. Hashmi and R. Crampton, J. Inst. Mech. Sci. (in press)).