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Adhesion of powder onto tools during compaction: A numerical study
Journal article   Peer reviewed

Adhesion of powder onto tools during compaction: A numerical study

David Freiberg and Antonios Zavaliangos
Powder technology, v 407, 117644
Jul 2022
DOI: https://doi.org/10.1016/j.powtec.2022.117644

Abstract

During the compaction of powder into tablets, often material from the tablet is detached and stays on the tool punch. This phenomenon is called “sticking” and is a persistent problem and not well understood. In this work, we simulate sticking with DEM (Discrete Element Method) for the first time. The simulations demonstrate the role of inhomogeneity of the deformation at the contacts and the interplay of wall adhesion and interparticle cohesion on the development of sticking. We provide evidence that the maximum tensile force during the separation of punch from the tablet by itself is not a sufficient proxy for sticking, and show that two materials differing only in interparticle cohesion and particle-tool adhesion can produce the same maximum tensile force and yet have opposite sticking behaviors. The simulation results suggest that a merit figure for sticking can be derived for compacts made from a single type of powder, using the maximum separation force and the strength of the compact, but caution is advised when attempting to use it in conditions that are not compatible with the simplifying assumptions of the model used in this work. [Display omitted] •Sticking in powder compaction cannot be measured via only one experimental variable.•Sticking can occur even when particle-wall adhesion is less than particle-particle cohesion.•The Discrete Element Method is a useful tool to study the failure modes of compacted powders.

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