On the role of forces governing particulate interactions in pharmaceutical systems: A review

Assessing Die Filling Using High‐Speed Camera Imaging

“…High‐speed camera images reveal a homogeneous powder entering the die indicating least inter‐particle cohesion. This observation can be explained by (1) the high gravitational force that is acting on the large particles overcoming non‐contact forces and favoring discharge into the die . Furthermore (2) the very smooth surface of the spherical particles (Fig.…”

“…1) and almost perfect spherical shape (Fig. 3) prevents particle-particle friction and decreases the non-contact forces (van der Waals, capillary, and electrostatic forces) [15]. It shows the fastest and complete filling in 165 ms (Fig.…”

“…This material has the largest particle size of all materials under investigation (Tab. This observation can be explained by (1) the high gravitational force that is acting on the large particles overcoming non-contact forces and favoring discharge into the die [15]. 3).…”

“…Lycatab C discharges in a bunch of small and low density agglomerates at the beginning (t 1 ) of die filling. 3) increase the cohesive forces which become more important relative to particle weight [15] preventing the discharge from the shoe into the die. 8).…”

“…In general, a decreased mass flow rate for increased particle size is observed by the Beverloo correlation at constant orifice diameter in hopper discharge studies [18 -20]. In case of small particles, the non-contact forces can exceed the gravitational force thereby hindering powder discharge from the shoe into the die [15], resulting in a decreased Q% t . In this study, the materials considered (d corresponds to x 50 ) and the system used (D corresponds to die diameter) show D/d in the range of 44.6 -123.3 (Tab.…”