Feeding of particle-based materials in continuous solid dosage manufacturing: a material science perspective

Review of sensing technologies for measuring powder density variations during pharmaceutical solid dosage form manufacturing

“…Powder densification can cause failure modes, such as flow stagnation, feed rate variations associated with hopper agitation and during refill cycles, screw clogging and agglomeration of the fed material as discussed by Hsiao et al [9]. Consistent feeding of the correct mass of individual materials or blends over a long time is required to achieve high quality of intermediate products, such as granules or extrudates.…”

“…Consistent feeding of the correct mass of individual materials or blends over a long time is required to achieve high quality of intermediate products, such as granules or extrudates. The crucial condition affecting feeding performance is the local state of material densification at key zones within a feeder, i.e., at the screw inlet region, in the screw and at the outlet [9].…”

Continuous twin screw granulation and fluid bed drying: A mechanistic scaling approach focusing optimal tablet properties

“…The most common feeders, being used for dosing processes within continuous pharmaceutical manufacturing, are the loss-in-weight feeders (LIW) [5, 9,24,25,26,27,39,40,47,60,67,117,119,124,125]. The general setup of such a loss-in-weight-feeder with its three main components is depicted in Figure 4.…”

“…Overview on the three main components of a loss-in-weight feeder [5, 24,25] The loss-in-weight feeder can be operated in an either volumetric or a gravimetric mode [5, 24,25,27,40]. In a volumetric operation mode, the screws of the feeder transporting the powder are running at a constant screw speed resulting in a certain powder feed rate.…”

“…Changes in powder feed rate may occur in this operation mode, as inconsistencies in the powder bulk directly affect the powder feed rate [39]. Furthermore, a decrease of the powder feed rate at decreasing fill level inside the hopper was observed by several researchers [26,40]. Therefore, the volumetric feeding mode is not as reliable and accurate as the gravimetric feeding mode.…”