The Importance of Troubleshooting In-Process Charge Buildup

Electrostatic charge buildup is a common issue encountered during powder processing. The charge buildup arises from the frictional contacts between particles, leading to electrostatic charge creation due to tribocharging mechanisms. The accumulation of electrostatic charges during the processing will induce a drift in the material, in particular in continuous manufacturing processes. The electrostatic-related inter-particle forces will contribute to an increase in the powder cohesiveness with associated reduction of the flowability. Also, charge buildup will typically lead to heavy sticking of fine particles on the machine surfaces, leading to powder accumulation and pipes clogging as well as an uncontrolled drift in the particle size distribution. Therefore, it is essential to understand the electrostatic properties of the processed material to mitigate the charge buildup and improve the stability during processing.

The GranuCharge instrument allows for the investigation of the tribocharging properties of powdered materials in the lab. The instrument is very well suited for the evaluation of the influence of the material properties, such as the particle size and shape, chemistry… and the interaction with the external environment (relative humidity, machine parts material) on its chargeability. The information gathered with the GranuCharge can then be applied to a lot of different processes. However, it does not allow direct evaluation of the charge buildup in a specific production line or at different stages of the process. Sampling in the production line and then transferring the sample to the lab for an electrostatic charge evaluation is usually not feasible, as the charges in the sample will likely dissipate during transportation.

To overcome this limitation, a new product has been developed: the GranuCharge At Line. The GranuCharge At Line is a portable device that can be placed directly inside the production line. It includes everything you need to make a charge density evaluation: A Faraday cup coupled with an electrometer and a weighting device. With the GranuCharge At Line, the process-induced charge buildup can be directly assessed for your specific process. Its compact shape allows to perform sampling at the output of feeders or hoppers, mixers and blenders, and more generally at any stage of the process. This allows you to get a full picture of the charge buildup across your production line to identify the problematic parts of the process that need to be improved. Moreover, the results obtained with the GranuCharge At Line can be combined with the ones obtained in the lab to have a complete understanding of the influence on electrostatic charge buildup of the material properties and the interaction with the process line parts. The best compromise between powder characteristics and process settings can be found to reduce processing troubles and improve the quality of the final product.

Learn more about the GranuCharge

Learn more about the GranuCharge at Line