When the author of this book was a small child, Wistreich performed extensive experimental work in which he studied steel and copper wiredrawing. In this connection, he applied longitudinally split dies and measured both the drawing force and the die-splitting force in the drawing operation. From the measured data, he calculated the mean contact stresses on the die wall, by means of the formulas presented in the Sec. 22.5. From the contact stresses, he finally determined the mean coefficient of friction for the various drawing geometries used in his investigation. In the following, more details about Wistreich's copper wiredrawing experiments will be presented. In addition, some of his experiments will be reproduced in FEA to characterize the mechanics of these approximately 50-year-old experiments. As will be shown, the mechanics of wiredrawing are complex and are changed a lot when the drawing geometry is altered by changing the parameter Δ and the reduction of area in the die.

In Wistreich's experiments, the die geometry was varied by varying two parameters: the cone angle and the reduction of area in the die. A large number of experiments were run, and many different die geometries were tested. The die half cone angle was varied from ≈3° up to ≈15.5°, and the reduction of area correspondingly from 0.05 to 0.45. Nine of Wistreich's experiments were later reproduced by FEA, and an additional case corresponding to normal drawing will be considered here.