Assessing the performance of innovative blending technology.
Flow aids can substantially enhance powder flowability and are used throughout powder processing industries to improve process and product performance. Optimised blending maximises gains with efficacy reliant on the dispersion of a fine layer of flow aid across the surface of the host particle. A study of novel blending technology, Magnetically Assisted Impaction Coating (MAIC) (Aveka, Woodbury, MN), demonstrates the value of applying multi-faceted powder testing to assess the impact of flow aids and compare the performance of different blending techniques.
Dynamic and shear powder properties were measured for blends of silica/citric acid blends (FT4 Powder Rheometer®, Freeman Technology, Tewkesbury, UK), produced by V-blending and by MAIC. Silica is a widely used flow aid and was incorporated at a concentration of either 0.5 or 2.0% w/w. MAIC actively promotes particle attachment via a pounding action applied by magnetic particles induced to accelerate and spin by an oscillating magnetic field. The results indicate that this technology is significantly more effective than V-blending in achieving enhanced flow properties via the incorporation of silica.
Basic Flowability Energy (BFE) values for the 0.5% silica MAIC sample are comparable to those of the 2.0% V-blended sample illustrating how more effective dispersion can reduce the amount of flow aid required to achieve a defined improvement in flowability. Aerated Energy (AE) values similarly illustrate the ability of MAIC to boost the effectiveness of the flow aid. Lower AE values indicate that the inclusion of flow aid reduces absolute cohesion within the powder bed, enhancing fluidisation characteristics.
Cohesion data also differentiate MAIC performance but suggest a relatively modest difference at 2%. Cohesion is a shear property, measured under relatively high stress, compared with the low stress conditions applied during dynamic measurements (AE and BFE). The results suggest that dispersion efficiency has a less pronounced performance under these conditions and at the same time highlights the ability of dynamic measurements to differentiate the blending technologies with greater sensitivity.
Finally, SI data provide insight into the stability of flow aid dispersion. The flow energy of the MAIC samples is effectively constant over repeat measurement cycles (SI close to 1) while that of the V-blended samples reduces (SI << 1) particularly at the lower silica concentration. This suggests that the testing process itself is progressively dispersing the flow aid. Since these samples were tested post-shipping the results are consistent with MAIC producing stable blends that are resistant to segregation during transport while V-blended samples exhibit segregation which is subsequently reversed by the testing process.
In combination the results confirm that MAIC produces more stable blends than V-blending with enhanced flowability under all flow regimes, at low (AE), moderate (BFE) and high stress (Cohesion – shear). This comprehensive assessment relies on the application of both shear and dynamic powder testing, highlighting the value of testers that apply multiple test protocols.
Read on to find out more about the impact of flow aid concentration and the complementary insight provided by bulk property measurement.
Freeman Technology
- +44 (0)1684 851 551
- info@freemantech.co.uk
- https://www.freemantech.co.uk
- 1 Miller Court Severn Drive Tewkesbury Gloucestershire GL20 8DN GB
About us
Freeman Technology specialises in systems for measuring the flow properties of powders and has nearly 20 years' experience in powder flow and powder characterisation.
The company invests significantly in R&D and applications development, and provides detailed know-how to support its range of products. Expert teams guide and support users around the world in addressing their individual powder challenges, focusing on delivering the most relevant information for the process. The result is world-leading solutions for understanding powder behaviour - in development, formulation, scale-up, processing, quality control, or anywhere that powders have a role.
Freeman Technology’s solutions include the FT4 Powder Rheometer®, a uniquely universal powder tester, and the Uniaxial Powder Tester, a complementary tool for quick and robust powder assessment. Systems are installed around the world in the chemical, pharmaceutical, toners, foods, powder coatings, metals, ceramics, cosmetics, and many other industries. They deliver data that maximise process and product understanding, accelerating R&D and formulation towards successful commercialisation, and supporting the long term optimisation of powder processes.
Founded in 1989 as a developer of automated testing systems for materials characterisation, the company has focused exclusively on powders since the late 1990s and in 2018 became part of Micromeritics Instrument Corporation. The company’s R&D, manufacturing and commercial headquarters are in Gloucestershire, UK, with operations and distribution partners in key global territories. In 2007 the company received the Queen’s Award for Enterprise in Innovation and in 2012 the Queen’s Award for Enterprise in International Trade.
Where we supply to
UK Ireland, Europe, Africa, Asia, Australia, South America, North America
Industries we supply to
Chemicals, Food and Beverage, Pharmaceutical Cosmetics Toiletries
