Freeman Technology has published a new white paper that describes extensive experimental studies examining the multiple mechanisms that lead to powder caking. Caking is a routinely encountered problem within powder handling applications which compromises productivity and increases waste.
The new white paper ‘Investigations into homogeneous and non-homogeneous caking and crusting in powders using powder rheology’ demonstrates how dynamic powder testing can be used to quantify caking behaviour under different environmental conditions. The resulting data support the development of strategies that reduce caking and maintain optimum powder processability.
More than 70% of the materials handled in the food, pharmaceutical and chemical industries are powders. The ability of these materials to flow freely is often fundamental to their industrial value and this is obviously compromised by caking. Caking is the result of an increase in the strength of particle-particle interactions in a powder and is caused by exposure to temperature, humidity and/or stress. Understanding whether a raw material, intermediate or final product is likely to cake, and under what conditions, is an essential precursor to identifying policies that avoid the problem.
Freeman Technology has used powder rheology to investigate thermal, chemical and mechanical caking mechanisms in several different powders, including food, polymer and detergent systems. Tests have been carried out with the FT4 Powder Rheometer®, a universal powder tester that provides dynamic, shear and bulk powder property measurement. The results show that dynamic powder flow properties are highly relevant for the quantification and elucidation of caking and crusting mechanisms. In particular, the ability of dynamic testing to measure the strength of a crust within a powder bed, as a function of bed height, provides unique insight into the effect of moisture absorption on caking behaviour.