Friction modelling for the physical simulation of the bulk metal forming processes

To validate the analytical and numerical analyses, it is necessary to perform the relevant experiments. In the case of a metal forming process, however, when a model test is conducted instead of the real one, many benefits can be gained. One of important dimensionless numbers that should have the same value in both the real and model tests is the friction factor. But various forming processes involve different friction conditions. In the present research work a gravity-drop model hammer, designed based on the similarity laws, was employed to carry out several ring tests at medium strain rates. With this regard, various lubricants and friction conditions were used with Plasticine rings. Thirteen lubricants and conditions were also employed to conduct the ring tests of the lead specimens with a 600 KN Instron testing machine. For comparison, a few extrusion friction tests were also performed. The tests with the lead as the model material were carried out at relatively low strain rates. By means of the experiments with lead and Plasticine, it was shown that a full range of friction conditions, from nearly zero friction to sticking friction, could be modelled for the physical simulation of the bulk metal forming processes. (C) 2004 Elsevier B.V. All rights reserved.