High-capacity beverage filling can lead to liquid sloshing when rotation speed and changes in direction act on the contents of the bottle, especially at the handover from the filler to the transfer star and on to the capper. Even when this amounts to only a few drops per container, the cumulative loss becomes significant at throughputs of up to 90,000 fills per hour. Beyond efficiency, hygiene is affected as sugary beverages can soil necks and closures, in some cases promoting mold formation, while machine components become contaminated. This increases cleaning requirements and shortens available production time. To counter these issues, KHS bases machine design decisions on extensive calculations that predict and mitigate sloshing behavior under realistic operating conditions.
Simulation-based approach
Since 2013, KHS development engineer Dominik Weirich has been preparing calculations to incorporate liquid dynamics into the engineering workflow. "Ever higher filling outputs mean that the technology’s reaching its physical limits, so that we also have to take liquid sloshing into account when designing the machine," says the KHS development engineer at the factory in Bad Kreuznach, Germany. Data from these simulations feed directly into machine design and into commercial offers for new lines.
Two groups of parameters
The calculations address two parameter groups that govern sloshing risk and can be adjusted to varying degrees during a project.
- Geometric parameters of the containers: the influence of bottle shape, fill height and neck diameter is evaluated. This work is done in close consultation with Bottles & Shapes experts, particularly in new line projects that modify geometry or reduce bottle weight.
- Physical parameters of the machines: capacity, machine pitch and the diameter of the stars are considered. These settings can usually be adapted relatively easily compared to container changes, which tend to be iterative and more extensive.
Different centrifugal forces act on the product in the bottle as it passes from the filler to the transfer star and capper.
Guidelines and outcomes
As a general rule, the larger the exposed product surface and the closer the liquid level is to the bottle mouth, the higher the likelihood of sloshing. Based on these relationships, the results of the simulations are incorporated into engineering decisions and proposals. To date, approximately 850 simulations have been performed, with the number continuing to rise.
