Finite Element Modeling of Powder Compaction: Mini-Tablets in Comparison with Conventionally Sized Tablets.

INTRODUCTION: Mini-tablets are considered a promising solid dosage form in the pharmaceutical industry due to advantages such as dosing accuracy, efficiency as a drug delivery system, and alleged improvement in mechanical properties. Nevertheless, only a few experimental studies are available in the literature regarding this topic and technical aspects, such as punch's shape and size effect on the stress and density distribution in the compact mini-tablets, are still not fully investigated. OBJECTIVES: In this paper, the influence of powder properties and process parameters, such as punch shape and size, on the evolution of mechanical properties during the tableting process and the potential occurrence of tablet defects are investigated using the mechanistic modeling approach, Finite Element Method (FEM). METHODS: The numerical simulation cases consist of four different die sizes, mini-tablets of 2 mm, and 3 mm, and conventionally sized tablets of 8 mm and 11.28 mm. Each tablet size is simulated using four distinctive excipients, Avicel® PH-102, Kollidon® VA64, Pearlitol® 100SD, and Supertab® 11SD, and two different punch geometries, a flat-face punch, and a bevel edge punch. RESULTS: The model predictions in terms of stress and density distribution at different stages of the compaction process indicate similar behavior in terms of density and stress distribution profiles between the conventionally sized tablets and mini-tablets for a particular excipient. CONCLUSIONS: Based on tablet size, small localized differences are noted (e.g., low-density regions, high shear bands, and heterogeneous density profiles), suggesting a possible risk of tableting defects for conventionally sized tablets compared to mini-tablets. Furthermore, it is observed that bevel-edged tablets could facilitate the formation of cracks, leading to possible capping failure.

Investigating screw-agitator speed ratio impact on feeding performance in pharmaceutical manufacturing using discrete element method.

In continuous powder handling processes, precise and consistent feeding is crucial for ensuring the quality of the final product. The intermixing effect caused by agitators, which alters the powder's bulk density, flow rate, and flow patterns, plays a significant role in this process, yet it is often overlooked. This study combines discrete element method (DEM) modeling and experiments using a commercial-scale feeder to propose a Digital Twin (DT) framework. The DEM model accurately captures key flow features, such as bypass trajectories, stagnant zones, and preferential flow patterns, while providing quantitative predictions for the feed factor and zones prone to material accumulation. Scenario analysis is performed to identify the most favorable operating ranges of the screw-agitator ratio and screw speed, considering the cohesive properties of the powder. The study demonstrates that powders with poor flow characteristics require tighter operational constraints, as the screw-agitator ratio is susceptible to variations in mass feed rate. This contribution highlights the importance of selecting an appropriate screw-agitator ratio instead of maintaining a fixed value. Properly choosing this ratio helps determine an optimal operation window, which aims to achieve a minimum agitation level needed to induce unhindered flow and reduce variability in the mass flow rate.