The effects of material attributes on capsule fill weight and weight variability in dosator nozzle machines

The goal of this work is to identify and understand the complex relationship between the material attributes, capsule fill weight and weight variability of capsules filled with a dosator nozzle machine. Six powders were characterized and filled into size-3 capsules in three volumes of dosing chambers and at two filling speeds. Subsequent multivariate data analysis was used to identify the influence of the material attributes on the capsule fill weight and weight variability. We observed a clear correlation between the capsule fill weight and the particle size, the air permeability and the compressibility. As the fill weight decreases, more factors affect capsule fill weight. For example, the wall friction angle, the tapped density, and the particle shape proved to be important factors. Larger fill weights were more affected by density while lower fill weights by flow and friction characteristics. No correlation was found between the material attributes and the weight variability. Rather, we could also see the major effect of process parameters on capsule fill weight and weight variability.