Finite element modelling and associated experimentations to optimize and predict the pressing cycle of a future AMBB manufacturing press

This study presents an approach based on the use of pellet forming numerical digital simulation which enables optimization of the die pressing cycle. Semi-empirical mechanical models were used in an FEM code, CAST3M. Specific powder characterizations were also performed to supply the mechanical parameters of compaction model. The methodology for the identification of five main coefficients (index flow, elastic and plastic parameters) was used with two different powders. The results show that the axial distribution of frictional forces may be changed during die pressing by a modification of the sequence of punch displacements. According to these results and the literature, the pressing cycle can be considered to have an influence on the shape of a sintered pellet through the axial distribution of green density. The process used for the identification of the Cam-Clay model coefficients seems to be in good agreement, even if the changes in certain parameters remain rather unclear and will require follow-up studies to confirm some of the results. The experimental device used produces good quality pellets, and the Radial Open Die Modulus remains the first choice for reduced pellet damage. Much work still remains to be done to fully define the identification process and create the most representative simulations possible before launching an industrial version of a nuclearized press, planned for the last quarter of year 2014. (authors)