Production rate limitations can develop when feeding fine powders to a press, granulator or mill. These powder feed rate
limitations arise when the powder interacts with entrained air, resulting in adverse “two-phase” (powder-air) flow effects.
Two-phase flow problems can result in out-of-specification tablets, requiring operating at below target production rates. A
critical step in developing a robust process, including conducting Quality by Design (QbD) studies, is modeling two-phase flow
behavior in the press feed system.