Whether filling to a level or filling by volume, inconsistency in the packaging process can cause headaches for a packager. Inconsistency when filling to a level can affect the way a product looks on the shelf, taking away from the benefit of aesthetic appeal provided by overflow filling machines. Inconsistent volumes can leave some consumers feeling cheated or even punishments for those in an industry where specific volumes are required. While there are many different causes of inconsistency when using an automatic filler, many times the inconsistency can be corrected through an easy fix. Below are some of the most common causes of inconsistent fills.
1. Machinery Is Not Leveled
To function properly, almost any piece of packaging machinery must sit level on the production floor and liquid fillers are no different. Most designs allow for adjustments with simple leveling legs that can help to raise or lower the machine as necessary. Check the equipment with a level and adjust the machine using the legs as necessary. Once level, run a test cycle with bottles under the fill heads to see if the issue has been corrected.
2. Pump Duration or Fill Times Are Off
On fill-to-level systems, product will normally overflow out of the bottles and back to a holding tank. The pump must remain on long enough to allow liquid to overflow in each of the individual bottles to achieve the level fill. A short pump duration may mean not all bottles are reaching the desired level. The operator can usually perform a visual inspection during a fill cycle to ensure that all containers are reaching the level and the overflow takes place. If not, simply adding some time to the pump duration of an overflow filler may solve the problem. As a side note, operators of fill-to-level systems should also check to ensure that overflow tubes are not submerged in liquid, which can create back pressure and cause havoc with fill levels.
For volumetric fillers, each individual fill head may be timed separately. This may simply mean that the nozzle may open for a set amount of time or that a certain time is set for a pump “pulse” (for example, a turn, or fraction of a turn, of a gear in the pump). Keep in mind that an inconsistent fill on a volumetric filler does not mean levels will vary in the bottles. Instead, it means different volumes of product are being dispensed into different bottles. Operators must check the volume of completed fills to determine if volumes are inconsistent and then adjust the necessary fill heads as needed.
3. Product Pathway Connections
Automatic bottle fillers will pull product from a bulk tank or other supply, with some using a holding tank to supply product to the bottles. The product will still travel through some pathway, via tubes and cylinders, to reach the containers. Operators of packaging machinery experiencing varying fill levels on overflow fillers or varying amounts on volumetric fillers must check the product pathway for leaks. The operator may not necessarily see product seeping from any of the connections. Loose clamps or tubes may allow small amounts of air to enter the pathway, creating the inconsistent fill. Simple check and tighten all connections on the machine and run a test cycle to see if the issue is resolved.
4. Wear Parts
Certain parts of liquid fillers will come into contact with product, bottles or both. These and other parts can wear and require replacement over time. On overflow, or fill-to-level, fillers, special nozzles are used to create a seal on the bottle. These seals, along with springs and O-rings, may all need to be replaced from time to time. Visually inspect the nozzles to ensure the seal on the bottle is sufficient, that springs have not lost tension or for other signs that parts may require replacement. Some pumps and nozzles on volumetric fillers may also require replacement, and the same visual inspection should be done on the volumetric liquid filler if fills become random or inconsistent.
5. Fill Hold/Supply Hold Functions
Automatic bottle filling machines will often include fill hold and supply hold functions in the set up menu of the operator interface. These functions can be turned on and off by the operator of the equipment. In general terms, the fill hold stops the machine from beginning a fill cycle while the supply tank is being replenished. On the other hand, the supply hold stops the equipment from replenishing the tank until the current fill cycle is complete. Check to ensure these functions are turned on during production runs if levels become random.
Finally, while most bottles are manufactured in a way that each bottle will be nearly identical to the others, some unique containers may simply vary greatly in internal volume. In those containers where internal volume does vary by a wide margin, volumetric fills may result in wildly erratic fill levels. On the other hand, some packagers that must hit a volume range still choose to use a fill-to-level system for the aesthetic value. In these situations, packagers must check the range of the internal volume on their bottles, to ensure that the level fill will still land within the acceptable volume range. While this issue is rare, those packagers experiencing erratic fill levels will want to inspect their bottles as well.
While the above list does not provide an exhaustive list of possible causes for inconsistent performance, the issues described above likely account for more than half of all occurrences of erratic filling. For those that cannot rectify their levels issue after running through this list, it is probably a good idea to contact your machinery manufacturer or a local service representative to take a deeper look into the problem.
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