Compaction analysis and optimisation of convex-faced pharmaceutical tablets using numerical techniques

Capping failure, edge chipping, and non-uniform mechanical properties of convexfaced pharmaceutical tablets are common problems in pharma industry. In this paper, Finite Element Modelling (FEM) and Design of Experiment (DoE) techniques are adopted to find the optimal shape of convex-faced (CF) pharmaceutical tablet which has more uniform mechanical properties and less capping and chipping tendency. The effects of the geometrical parameters and friction on the compaction responses of convex-faced pharmaceutical tablets were first identified and analysed. The finite element model of the tabletting process was generated using the implicit code (ABAQUS) and validated against experimental measurements. Response Surface Methodology (RSM) was employed to establish the relationship between the design variables, represented by the geometrical parameters and the friction coefficient, and compaction responses of interest including residual die pressure, the variation of relative density within the tablet, and the relative shear stress of the edge of the tablet. A statistical-based optimisation approach is then employed to undertake shape optimisation of CF tablets. The obtained results demonstrated how the geometrical parameters of CF tablet and the friction coefficient have significant effects on the compaction behaviour and quality of the pharmaceutical tablet