In industrial processes such as blending, transfer, storage, feeding, compaction and fluidisation the reliable flow of powder plays an important role since it can affect the quality of the final product or production rate. Poor flow leads to wastage, machinery maintenance problems and downtime, with associated costs.

There are a number of test methods for evaluation of flow behaviour of powders, such as the unconfined compression test, shear test and a few recently developed techniques, such as the Sevilla powder tester, the raining bed technique and Freeman FT4 rheometer. Within our research group we have access to a number of devices for evaluation of powder flowability:

  • Schulze Ring Shear Tester
  • Instron 5566 Test Bench – used for uniaxial compression tests
  • Geldart’s angle of repose tester
  • Ball Indentation
  • Freeman Technology FT4 Powder Rheometer
  • Tap density

In a recent research programme we developed a new technique for measuring flowability of cohesive powders based on ball indentation on the surface of a powder assembly. This technique requires very small quantities of powder and can be applied on loosely compacted beds, making the technique beneficial to industries with problems of accessibility or availability of the testing powder e.g. pharmaceutical industries with limited amount of powder in the early development stage or in the nuclear industry, where the amount of powder available for testing is limited due to ionising radiation risks.

Recently we have developed an accelerated test method for powder caking, the Environmental Caking Rig (ECR) that enables rapid conditioning of a powder to desired environmental conditions and measurement of how powder flowability is transformed, which provides insight into how a bulk powder will behave in a supply chain during storage.