Uniaxial Powder Tester

The Freeman Uniaxial Powder Tester (UPT) is a unique, stand-alone uniaxial shear tester for simple, sensitive and cost-efficient powder characterisation. The instrument delivers repeatable and reliable measurements, providing a robust, cost-effective alternative to traditional powder testing techniques.

UPT measures uniaxial unconfined yield strength (uUYS), a parameter typically derived indirectly via biaxial shear cell analysis, which is widely used to assess and rank the flowability of powders. It involves measurement of the force needed to break or fracture a column of consolidated powder.

Advantages of Uniaxial Shear Testing

  • Direct uUYS (σc) and Flow Function (FF) measurements
  • Fast
  • Repeatable
  • Low Cost
  • Versatile
  • Easy to use
  • Intuitive, easy to interpret results
  • Robust
  • Bespoke software

The Consolidation Station (for off-instrument consolidation) is useful when a powder needs to be consolidated for an extended period of time or within a controlled environment (for example at a fixed relative humidity or at elevated temperatures). This allows for the simulation of many industrial processes without occupying instruments for long time periods.

The Consolidation Station can provide up to 100 kPa of applied stress and can be placed in an oven at temperatures up to 70°C.


Uniaxial testing first involves the construction of a consolidated powder column. This is then removed from its confining sleeve before being fractured through the application of a vertical stress, directly measuring the uniaxial Unconfined Yield Strength (uUYS). This technique can therefore be used to assess and rank the flowability of powders.