MODELING AND SIMULATION OF METAL-POWDER DIE PRESSING WITH USE OF EXPLICIT TIME INTEGRATION

The pressing of hard metal components is analysed with numerical metho ds. The analysed components are selected from produced components for which the density distribution in the material after pressing has been measured. The expected results from the analyses are the density dist ribution and the springback after unloading and ejection of the compon ents. The highly non-linear quasistatic problem is analysed with the u se of explicit integration of the equations of motion. A contact const raint method based on direct integration of the equations of the conta ct interface is used in the analyses. The contact and friction algorit hms have been developed in earlier work and are further verified by an alyses of a test problem that has an analytical solution. The behaviou r of the powder is described by a special cap plasticity material mode l developed for powder applications. In one example the results obtain ed using the cap model are compared with results obtained with a multi surface plasticity model. The parameters of the constitutive models ar e fitted to triaxial experimental dat through optimization methods. Th e presented methods are evaluated by comparing the results with experi mental data from density measurements where a technique based on gamma ray absorption is used. The density distributions are qualitatively i n good agreement with experimental results. The springback obtained in the simulation of unloading and ejection is in good agreement with me asured values.