Performance Characteristics of a Novel Vibration Technique for the Densification of a Powder Bed within a Die of a Rotary Tablet Press - a Proof of Concept.

The aim of this study was to investigate the concept of lower punch vibration as a possible approach to densify the powder bed within the die of a rotary tablet press. Therefore, a laboratory vibration equipment was developed to obtain a better understanding of the performance characteristics and effects of a pneumatically generated vibration system on pharmaceutical powders. For this purpose, two widely used pharmaceutical powders, basic magnesium carbonate (Pharmagnesia MC Type F) and microcrystalline cellulose (Ceolus® KG1000), both with different physical properties, were investigated. The powders were characterized by laser diffraction, scanning electron microscopy, helium pycnometry, ring shear testing, gas adsorption, and by determination of the powder flowability. Furthermore, the extent of densification within the die during vibration was visualized by a high-speed camera system and analyzed by an image-analyzing software. It was observed that lower punch vibration was able to densify the powder bed to a sufficient extent and within an adequate time period. Consequently, the presented results revealed that lower punch vibration may be a promising technique to remove entrapped air from powder beds, thus obtaining a denser powder bed within the die, which might potentially improve the tableting process and prevent complications during tablet manufacture.