Abstract
Scaled progressive dry deep-drawing test is conducted up to 300 times on the micro- and milli-scales, in which cups of 0.97 and 5.82mm diameters are produced with stainless steel foils of 0.05 and 0.3mm thicknesses, respectively. The experimental results show that the transition of maximum punch force in the repetition test has a different tendency for each scale and corresponds to the transition in the surface state of the tools and drawn cups. Although the strong adhesive wear is observed on the milliscale, there is little change in the surface state of tools and drawn cups on microscale. To investigate the wear behavior of work material on each scale, finite element analysis considering surface asperities is conducted. The distribution of wear volume at the die corner radius is evaluated with a semiempirical function of normal pressure and relative velocity between the blank and the die. The results show the low wear volume in the microscale process, due to the short sliding distance during the process. The progressive wear phenomena and the advantage of tool life in microforming are demonstrated.
