Influence of material and process parameters on the correction factor Kp in roller compaction simulation

It is widely believed that compaction simulators can replicate the uniaxial compression process of a roller compactor. The correction factor (Kp) is a parameter used to adjust a mathematical model for compaction simulation to obtain the same product relative density, therefore accounting for specific variables in machinery and scale up. However, the Kp has often been established for a single material and within a limited design space. This study investigates the impact of material and process parameters such as roll speed, roll gap and specific compaction force (SCF) on the Kp during roller compaction simulation. MCC, Starch and a 50:50 % blend of the two materials were used as model materials for the investigation. The relative densities from ribbons and riblets were measured using pycnometry and Kp was determined using ratio calculation of the respective relative densities. The influence of roll speed on Kp was found to be statistically significant (p < 0.05) for Starch, however the same influence was not statistically significant for MCC and MCC:Starch 50 %:50 % (p > 0.05). Furthermore, the influence of roll gap on Kp was found to be statistically significant (p < 0.05) for all three materials. The influence of the SCF on the Kp was found to be statistical significant for Starch (p < 0.05), however the same influence was not statistically significant for MCC and MCC:Starch 50 %:50 % (p > 0.05). In addition, the combined influence of the gap and material exhibits also a statistically significant (p < 0.05) effect based on Kp leading to a second-order combined effect. The interaction of SCF, roll gap, and material properties affecting Kp, indicates the need for a tailored approach when determining Kp for different formulations.