DOSING AND FEEDING | MACHINERY
Flexible options for feeding
The latest feeding and dosing equipment designs aim to optimise feeding of a range of materials. Jennifer Markarian reports
Accurate dosing of ingredients—liquids, pellets, fibres, powders, and other solid forms—into com- pounding equipment is crucial for quality results. Poorly flowing ingredients, such as cohesive powders or fluffy (low bulk density) dry materials, can be particularly challenging to feed. In addition, current supply-chain challenges, together with the drive to use more sustainable and recycled materi- als, mean compounders are needing to be able to successfully feed a wider variety of material formats. At the Kansas State Bulk Solids Innovation
Center in the US, researchers emphasise that reliable delivery of ingredients starts from how the material is received, stored, conveyed, and dosed to the process. “We have been doing work to optimise each of those aspects, because they have to work together, in concert, to ensure reliability of the feeding and dosing equipment,” says Todd W Smith, Manager of the centre. “We have been evaluating how material proper-
ties affect selection of best equipment and meth- ods. Since each ingredient has different properties, and the layout and use rates are different as well, no one method works for all ingredients. Delivery, storage, conveying, and feeding have to be fine-tuned for each ingredient. And in many cases, the equipment and methods used for one ingredi- ent is quite different than those used for another ingredient,” he explains. Having a feeder that can handle poorly flowing
materials is critical in many situations, as is versatility. Due to the ongoing supply chain challenges of recent times, compound producers are at times having to use materials or grades that are different from their usual choices and so may need to quickly change their feeder setup for that purpose, says Fabian Siffert, Global Market Insight and Sales
www.compoundingworld.com
Process Manager at Coperion K-Tron in Switzerland. “A compounding line may be set up for a micro-gra- nule titanium dioxide, but if this is no longer available they may have to switch to a titanium dioxide with poorer flowability,“ he cites as an example. Natural fibres are particularly challenging to
feed. “Natural compounds are sensitive to fluctua- tions within the ingredient mix and the breakage of the bulk materials. The feeding equipment must ensure a high accuracy and reduce the breakage of fibres to a minimum. Highly accurate vibratory feeders have been shown to be very successful in such applications,“ says Siffert. The use of natural powders, such as starches or
plant proteins used in bioplastics, is also challen- ging. “These materials are often dry and dusty but still somehow moderate flowing. But when they are under mechanical pressure, they become very sticky and poorly flowing. To address this problem, it is very important to set-up the whole process correctly, from storage until the bulk material gets fed into the extruder,“ Siffert advises. An energy-saving feature, which some are beginning to use for bulk materials coming directly
July 2022 | COMPOUNDING WORLD 13
IMAGE:
COPERION K-TRON
Main image: Feeder systems such as Coperion K-Tron’s ProRate Plus allow processors to more accurately control recipes
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