Powder Consolidation and Caking Rig

Caking is the tendency of a powder to form large agglomerates during storage and transportation. The tendency of a powder to cake is closely related to its cohesiveness and generally a powder that is cohesive will also form a definite cake during the caking test. The strength of the cake will depend on a number of factors such as packing efficiency, particle to particle interactions and moisture content i.e. humidity. Understanding the caking properties of a powder are important as most powders will be stored in hoppers or silos, or transported at some point in the production process. A powder that cakes easily and forms a strong cake may not discharge easily from a silo when required.

The sample is prepared by filling a static consolidation tube by approximately 50% (50% of the tube is marked internally as a visual guide). The mass of powder to fill to this volume is noted and then used for all subsequent tests of this material. A compactor, typically 2kg, is introduced into the tube and allowed to rest on the powder column under controlled environmental conditions for a given period of time. The compactor is removed at the end of the consolidation time and the sample is tested. A 46mm diameter Powder Flow Analyser blade moves down through the tube until it reaches a trigger force of 3g. The blade then begins to rotate through the consolidated powder column to a distance of 12mm. On reaching this distance the blade then returns to its starting position.    

A tube cap is placed on top of the tube after the compactor is removed to limit the exposure of the sample to the atmosphere prior to testing. The area under the curve in the mid-section of the graph is taken as the work to break the cake. The greater this value the stronger the cake.   

Granular material that has a tendency to cake.

• Requires a Powder Flow Analyser.
• Allows consolidation to take place aside from the instrument for a chosen period of time prior to assessment of caking.

Additional sample tube, base, cap and compactor sets are available to increase sample throughput and hence increase testing efficiency.