Freeman FT4

FT4: The Powder Flow Rheometer

The first FT Powder Rheometer was designed by Freeman Technology to characterise the rheology, or flow properties, of powders.

ft4Since launch the instrument and methodologies have been continuously developed to the point where the FT4 is now considered a universal powder tester.

The FT4 employs patented technology to measure the resistance of the powder to flow whilst the powder is in motion.

  • A precision ‘blade’ is rotated and moved downwards through the powder to establish a precise flow pattern.
  • This causes many thousands of particles to interact, or flow relative to one another, and the resistance experienced by the blade represents the difficulty of this relative particle movement, or the bulk flow properties.
  • The more difficult it is to move the blade, the more the particles resist motion and the harder it is to get the powder to flow.
  • Excellent reproducibility is achieved by moving the blade in a precise and repeatable way.
  • The advanced control  systems of the FT4 accurately set the rotational and vertical speeds of the blade, which defines the Helix Angle and Tip Speed.


There is a new ASTM standard for shear testing powders.

  • ASTM D7891 details the apparatus and procedures for evaluating the incipient failure properties of a powder under consolidation, including the determination of parameters such as Cohesion, Unconfined Yield Strength and Flow Function.
  • D7891 has been published by ASTM Subcommittee D18.24 on Characterization and Handling of Powders and Bulk Solids, part of ASTM International Committee D18 on Soil and Rock.

The principles behind all shear cell testers remain largely the same. The FT4, however, overcomes many of the recognised challenges by providing an easy to operate instrument with a fully automated test procedure and an intuitive software interface. The system is optimized to generate reliable, repeatable results, even when working with materials that are widely acknowledged to be challenging or when operating at exacting low stress conditions. In addition to the analysis of shear properties, the FT4 enables users to evaluate dynamic flow and bulk properties in order to understand how powders will behave across a wide range of conditions and in various unit operations.





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