Assess and Rank Powder Flowability with the Uniaxial Powder Tester

Freeman Technology’s Uniaxial Powder Tester (UPT) is an advanced, stand-alone uniaxial shear tester designed for sensitive, easy and cost-effective powder characterization. The device provides reliable and repeatable measurements, offering a robust and low-cost alternative to conventional powder testing methods.

Introducing Uniaxial Testing

The initial step in uniaxial testing involves the construction of a consolidated powder column. The confining sleeve is then removed to leave a free-standing column of powder which is fractured by the application of a vertical stress, providing a direct measurement of the uniaxial Unconfined Yield Strength (uUYS). This method can be used to assess and rank the flowability of powders.

Sample is loaded into a cylinder and consolidated with a Major Principal Stress (σ1) to form a powder column

Major Principal Stress and cylinder are removed to leave a free-standing consolidated powder column

Column is fractured through the application of a compressive stress

Cohesive powders have comparatively strong inter-particulate forces that encourage the particles to bond together instead of moving easily relative to one another. In non-cohesive powders, however, the tensile forces among the particles are likely to be relatively weak.

Uniaxial testing is a direct technique for measuring the uUYS (σc) of powders and determining the associated Flow Function (FF).

Key Features of the Uniaxial Powder Tester

  • Direct uUYS (σc) & FF measurements
  • Fast
  • Repeatable
  • Easy to use
  • Low cost
  • Versatile
  • Intuitive, simple to interpret results
  • Robust
  • Bespoke software

Consolidation Station

The offline Consolidation Station allows powder samples to be subjected to a range of environmental conditions, such as elevated temperature and humidity for extended periods under the desired MPS. This allows for the simulation of many industrial processes without occupying instruments for long time periods.

Temperature Range                  -20°C to +70°C

Humidity Range                        0 to 100% RH

MPS range:                               5kPa to 100kPa in 5kPa increments

At Freeman Technology a team of experts is always available for any immediate scientific and technical support.

Dr Arjen Tinke, Principal Scientist, Powder Characterization Janssen Research & Development (a division of Janssen Pharmaceutica NV)


  • Food
  • Chemicals
  • Ceramics
  • Cement
  • Plastics
  • Detergents
  • Pharmaceuticals

The Challenge of Uniaxial Testing

Practical limitations have previously restricted the exploitation of uniaxial testing. These include:

  • Ensuring a uniform stress and density throughout the entire powder column
  • Construction of a free-standing powder column
  • A practical, easy-to-use tester that can be used with a wide variety of powders

The UPT has overcome these challenges by:

  • Developing a sleeve design that enables the creation of a stand-alone column of powder
  • Use of a double-ended consolidation technique to facilitate uniform stress and density

Comprehensive Powder Testing

A range of powder testers have been developed by Freeman Technology to match the needs of users and their applications. The UPT is a practical and cost-effective method, which provides users with the opportunity to rapidly measure a defined set of parameters. However, the complex nature of powders, and the processes in which they are employed, typically require a more comprehensive understanding of flow properties.

This can be achieved with the FT4 Powder Rheometer® - a unique, universal powder tester that quantifies a diverse range of process-relevant properties.

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