Expedited investigation of powder caking aided by rapid 3D prototyping of testing devices.

Powder caking can dramatically affect powder handling and downstream production processes. Understanding the key factors that contribute to bulk powder caking is crucial. This article introduces the Hirschberg caking device (HCD), which is a 3D-printed device allowing for parallel testing of powder caking in a cylindrical geometry. In the HCD setup, the powder sample is stored in controlled conditions in the sample holder. On removal of the sample holder, the caked powder will remain in the shape determined by the sample geometry while the remaining powder will fall down. Caking indices can be calculated based on image analysis and weight measurement. The results obtained for the caking of lactose monohydrate with the HCD were in good agreement with the results obtained by a ring shear tester. In addition, a strain tester was used to measure the strength of the formed cakes. Using this approach, critical storage conditions and the required concentration of a given anticaking agent (talc) for lactose monohydrate could be identified. This work demonstrates the potential of rapid prototyping in powder characterization by introducing a fast and affordable approach for exploring and trouble-shooting powder caking.