Example: Product optimization with flow agent

An important quantity, which is measured with the Ring Shear Tester, is the flowability ffc. The flowability is a measure for the effort required to initiate flow. The larger the flowability, the better a powder flows. To find out the effect of a flow aid additive on the flowability, mixtures of the powder with different flow aid concentrations have been prepared and then tested with a shear tester.

Flowability vs. flow agent concentrationIn the diagram the flowability ffc of the product is plotted vs. the concentration of the flow agent (nano-powder). The red graph represents the instantaneous properties, while the blue graph shows the properties after 22 hours storage at rest (e.g., storage of the product in a silo or a container).

It is clearly visible that the flowability is smaller after 22 hours storage. This indicates that the product exhibits a pronounced time consolidation effect. Time consolidation is also known as "caking".

The flowability shows a maximum at a flow aid concentration of 0.55%, i.e., this flow aid concentration results in the best flowability. An increase of the flow aid concentration beyond 0.55% has a negative effect on the flowability.      

Further application examples

  • Quality control: Ensuring a product with good dosing behavior by limitation of the range of flowability.
  • Quality control: Ensuring a product which has a sufficient flowability even after storage at rest over a long period of time.
  • Investigation of the influence of the particle size distribution on the flow behavior.
  • Investigation of the influence of the storage temperature on the time consolidation effect (caking).
  • Optimization of production processes regarding good flowability of the products..
  • Optimization of the powder composition for homogeneous filling of the dies of a tablet press.

Publications on the application of Ring Shear Testers

The use of Ring Shear Tester measurements for various applications is described in a number of publications. Some of these publications can be found in this list:

List of publications (pdf)

International Round Robin test on Ring Shear Testers

Some years ago, an international Round Robin test took place on our ring shear testers (small tester RST-XS; large tester RST-01.pc), in which many of our customers in Europe and the USA participated.

Round Robin