Influence of the punch speed on the die wall/powder kinematic friction during tableting

Oct. 1, 2019, midnight - by Léo Desbois , Pierre Tchoreloff , Vincent Mazel

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Investigating the impact of compaction speed on the final tablet properties poses a significant challenge during the scale-up of solid dosage forms. While strain rate sensitivity is typically attributed to the time-dependent deformation behavior of the powder, this study delves into another crucial factor during compaction: the friction between the tablet/powder and the die. A novel experimental methodology was devised to examine the evolution of the kinematic friction coefficient between the tablet and the die in relation to the sliding speed of the tablet on the die wall. This approach allowed for the differentiation between the speed employed for tablet formation and the speed utilized for measuring the friction coefficient. The findings reveal that the kinematic coefficient of friction exhibits an increase with sliding speed, following a logarithmic trend. This trend was consistently observed across four different pharmaceutical excipients. Furthermore, it was demonstrated that the speed dependency is an inherent property of the friction between a tablet and a die lubricated with magnesium stearate.