1. The importance of friction

The first section describes the different methods of high-speed forming of metallic materials, while the second shows how numerical simulation can be used to map stresses, strains and temperatures on the basis of a behavior law established for a falling mass. In this third section, we look at how this numerical simulation approach can be used to evaluate the coefficient of friction between tools and material . The role of friction in high-speed processing can be positive or negative. When one of the tools is driven, as in rolling, then friction is necessary to engage and drive the product into the tool, though the level of friction must be controlled to avoid creating defects...