The effect of material properties and process parameters on die filling using double-tip tooling: A PLS-model-based analysis.

Up-scaling on a rotary tablet press by increasing turret speed can have a negative effect on die filling performance, as the dies have less time to be filled, leading to high tablet weight variability. For this reason, double-tip tooling is investigated, where a punch contains 2 tips instead of 1, doubling the throughput without the need to increase turret speed. However, when using multi-tip punches, one has to bear in mind that punch responses, e.g. pre- and main compression force, are the sum of each tip. When using these responses to assess tablet properties during compression, it is assumed that they can be divided over the total number of punch tips, i.e. an equal contribution of each tip to the response. This assumption can only hold when die filling is uniform across all tips. In this work, the impact of formulation material properties and process settings (X) upon die filling performance for double-tip tooling (Y) was studied, by developing and analyzing a PLS model regressing X versus Y. Additionally, this model enables the estimation of die filling variability based on material characterization data, eliminating the need for extensive tableting experiments and reducing material consumption in R&D.