Bag design in isostatic pressing

This paper presents the results of experiments and finite element simulations of the cold isostatic pressing of refractory tubes. Here a shaped rubber bag is filled with powder, sealed and subjected to high all-round pressure to produce a compacted green component with near net-shape. The stiffness of the rubber bag has an influence on the final compacted shape of the powder and this can lead to delays in developing the correct shape for the bag. The objective of this work was to predict the final shape of the compacted ceramic from the initial shape of the bag and the properties of the rubber and powder. The finite deformation simulations use a rigid-plastic, volume hardening plasticity model for the compacting powder and a hyperelastic model for the rubber. This has been implemented through a user subroutine within the commercial finite element code ABAQUS. The simulations give excellent agreement with experimental results for the pressed component shape.