(233ag) Characterization of Compaction Behaviour of Powders in Solid-Dosage Manufacturing Using Finite Element Analysis

Powder compaction is an essential step in pharmaceutical solid-dosage manufacturing, irrespective of the chosen path for powder pre-processing. The compaction changes the structure of material from a loose arrangement of particles with various shapes and sizes to a condensed structure that behaves like a continuum. An optimised compaction process is necessary to ensure production of high-quality tablets. Experimentally determining the effects of involved parameters and subsequent optimization of the compaction process is very difficult and expensive for this process, as tablets contain the expensive drug substance. Therfore, numerical simulation of the compaction process based on Finite Element Analysis (FEA) is suggested. The FEA is used for calculating forces, deformations, stresses and strains throughout a bonded structure, which is later used to ensure the formation of compact material with uniform density, free from cracks or chips. Hence, these simulations provide a detailed and cost-effective means of understanding and predicting the compaction profiles of the formulation material based on the processing parameters, such as imposed pressure, relative density of the powder and die shape.

In this study, the mechanical properties of a range of pharmaceutical formulations were approximated using the modified Drucker-Prager Cap (DPC) plasticity model and applied for FEA. The DPC model parameters were varied depending on the local relative density using an external subroutine. Additionally, the effect of wall friction on the mechanical behaviour of different formulation compacts during compaction is explored. This numerically predicted density distribution is compared with experimental measurements. The verification results are important for establishing a predictive capability of this model. The results from this study contribute to a better understanding of the impact of powder properties and process settings on the tabletting process and final properties of the produced tablet.