Through experimental study, experts from the two companies have identified easily measurable powder properties that can be used to predict screw feeder performance for any given powder. The resulting correlations support optimised feeder selection for a new powder on the basis of testing a small quantity of powder.
“For Gericke AG, selecting the best screw feeder for a given powder is an essential aspect of our business, and something our customers rely on us to do well,” said Daniel Büchi, Process Engineer at Gericke. “This study shows that, with the FT4 Powder Rheometer®, we can measure powder properties that will streamline this task. Being able to predict feeder flow performance from quick tests that require just a small amount of sample is potentially very valuable for us and for the wider industry.”
The joint research was undertaken by powder characterisation specialists, Freeman Technology, and Gericke AG, a leading developer and manufacturer of powder processing equipment for chemical, food, pharmaceutical and mineral handling.
In the study, tests were carried out using two different Gericke screw feeders - one compact and versatile for high accuracy feeding, the other a self-cleaning twin screw extruder for low capacity applications, especially well-suited to materials with poor flow characteristics. The volumetric flow rate delivered by each feeder was found to correlate with different powder properties in each case, but always with dynamic rather than shear or bulk powder properties.
“We designed the FT4 Powder Rheometer to measure dynamic, shear and bulk powder properties,” said Tim Freeman, Managing Director of Freeman Technology. “This multi-faceted testing approach produces a database of powder properties that allows the detection of parameters that are most relevant to any given process. We often find that it is dynamic properties that correlate most closely with in-process behaviour, as in this study. For both screw feeders we identified simple, robust correlations between flow rate and just one or two dynamic powder parameters.”