Abstract
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•Powder characteristics have a significant influence on powder flow behaviour during die filling.•For free-flowing powders, flow behaviours in linear and rotary die filling are similar.•For poor-flowing powders, a higher filling efficiency is achieved during linear die filling than rotary die filling.
In the pharmaceutical industry, linear die filling is widely employed in R&D, while rotary die filling is very common in commercial production. It is not clear if powder die filling behaviour in a linear die filling system is representative of the flow performance in a rotary tablet press. In this study, a linear die filling system and a rotary die filling system were used to examine flow behaviours of both poor-flowing and free-flowing powders. It was found that the performance of poor-flowing powder in the linear die filling system is slightly better than that in the rotary die filling system, while the performance of free-flowing powders in the linear die filling system is similar to that in the rotary die filling system. Hence, it is suitable to use the linear die filling system to estimate the flow behaviour during rotary die filling with free-flowing powders, but caution needs to be taken when poor-flowing powders are used.