Modeling gravity filling of dies on a rotary tablet press

For tableting on rotary presses, die filling is the qualitydominating process step as the tablet weight and its variation is influenced. Therefore, a deeper understanding of this process is necessary. In this study, the filled powder weight was investigated for various parameter combinations on a rotary tablet press in pilot-scale. Based on the obtained data for four materials, which differ in density and flow properties, a process-property model was developed to describe the volume flow into the dies. The flow can be used to calculate either the final tablet weight or the minimal paddle speed to fill the dies completely at a set turret speed, which supports process development. Finally, model parameters were correlated with the materials bulk density and permeability. Therefore, this models enables the prediction of the die filling process only based on geometrical data of the rotary press, process parameters and measureable material properties, for the first time.