Influence of Stamping Rate upon Springback Available to Purchase

The “Digital Die Design System” (3DS) international project has been launched following the undesirable lack of reproducibility observed in some Numisheet benchmarks. The main idea behind the project was to repeat the same stamping experiments in different labs or press shops, with exactly the same tools and conditions. In spite of all precautions taken to ensure a good reproducibility of the stamping process, a high level of scatter was found between partners for some geometries and couples of material‐lubricant. We discovered that a parameter, not neglected but insufficiently taken into consideration, was responsible for this scatter: it is the ram speed. Thanks to the quantity of recorded data, the examination of results finally drove us to see that, in certain circumstances, small differences of ram speed (i.e. 10 in place of 20 mm/s) were sufficient to strongly modify the level of springback, due to their influence on friction restraining forces. Consequences are discussed in the paper.