Dwell time on tableting: dwell time according to force versus geometric dwell time

Dwell time is an important parameter responsible for the material deformation and the mechanical and biopharmaceutical properties of the tablet. Thus, it is widely used for scale-up purposes. The geometric dwell time (GDT) can be assumed based on the shape of the punch head and the diameter and speed of the turret. This research is aimed to compare compaction simulator-recorded dwell time according to force (DTF) and the GDT calculated for the simulated rotary tablet press using the microcrystalline cellulose and calcium phosphate mixtures (CEOLUS (TM) UF-711 and DI-CAFOS (R) A60) in different proportions. Tablets were prepared, and DTF was analyzed with a compaction simulator (STYL'One Nano and Alix software) upon simulating a small rotary press at 70 rpm and a compression pressure of 10-50 kN (100-500 MPa). While GDT comprised of 14.4 ms, DTF was compression force and formulation dependent. The differences between the DTF values of the formulations decreased as the compression force increased, which was most pronounced at compression forces of 10 and 15 kN.