Modeling gravity filling of dies on a rotary tablet press

For tableting on rotary presses, die filling is the quality dominating 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 lab-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.

Highlights

Investigation of the gravity filling process on a rotary tablet press in lab-scale.

Developed model to describe gravity filling process.

Correlation of model parameters with powder properties like permeability and bulk density.

Prediction of the minimal paddle speed to fill dies completely for a set turret speed by using the model.

Very good agreement between predicted and experimentally determined minimal paddle speed for all investigated materials.

The flow can be transferred either into the final tablet weight or into 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 and measureable material properties, for the first time.

A.K. Schomberg, A. Kwade, J.H. Finke, Modeling gravity filling of dies on a rotary tablet press, Powder Technology, 2022, 117998, ISSN 0032-5910,
https://doi.org/10.1016/j.powtec.2022.117998.

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