Many in the packaging industry are likely well aware of the different filling machines available. Fillnig by volume offers several different solutions via gravity, pumps and pistons. Net weight fillers, as the name suggests, allows containers to be filled by weight. Overflow filling machines, on the other hand, allow each container to be filled to the exact same level, even if this means the volume or weight will vary slightly. At NPACK, we like to revisit the overflow filling machine from time to time, for those new to filling and the packaging industry.
The overflow filler is unique in that it is the only filling principle that allows each bottle to be filled to a specific level. The benefit of such a fill is probably obvious to anyone using a clear type container. Consumers would be wary of a container that allows the liquid to be seen, but also shows various levels of liquid in those bottles. Some may feel cheated. Some bottles, even if the volume was the same, may simply stay on the shelf if the fill was lower than others. But the machine has other benefits as well.
An overflow filling machine works by creating a seal over the bottle opening. As the nozzle dives in to the bottle, liquid is released in to the container via a fill port on the nozzle. When the liquid reaches the desired level, it will recirculate through an overflow port that keeps the liquid at the same level. The technique used in this fill makes the machine an ideal solution for products that foam as well. As more liquid is released in to the bottle, any foam that may form is forced out of the bottle by the liquid being added. While this may slightly increase the fill time, it creates a solution for the foam that would otherwise lead to inconsistent fills, or the need for even longer, slower fills on other machine types to control the foam.
Of course, a number of industries may require a certain volume, within a range, or tolerance. However, such a concern should not take the overflow filler out of contention when considering a packaging line. The technology used to manufacture bottles today will, in all but very rare cases, allow the overflow filler to be used while also keeping volume within the necessary range or tolerance. A conversation with the bottle manufacturer will typically allow a packager to get an idea of how much interior volume will vary with each bottle manufactured. For those packagers that already have their bottles, testing can also be done to ensure the overflow filler will meet the necessary range.
The overflow filler works best with thin, free-flowing liquids but can also handle some thicker, medium viscosity products. Very thick products may simply take too long to move through the product pathway to make this machine efficient. As noted above, the overflow principle is ideal for clear or nearly clear containers where the product is visible to the consumer. To learn more about overflow fillers as well as other filling options, check out the Filling Machinery section of the NPACK' website.