Whether filling to one level or filling by volume, inconsistency in the packaging process can cause a packager headaches. Inconsistency in filling to a certain level can affect a product’s appearance on the shelf, taking away the benefit of the aesthetic appeal that overflow fill machines provide. Inconsistent volumes can make some consumers feel cheated or even punished for those in an industry where specific volumes are required. While there are many different causes of inconsistency when using autofill, 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 level

To function properly, almost any piece of packaging machinery must be level on the production floor and liquid fillers are no different. Most designs allow for adjustments with simple leveling feet that can help raise or lower the machine as needed. Check the equipment with a level and adjust the machine using the feet as necessary. Once level, run a test cycle with bottles under the fill heads to see if the problem has been corrected.

2. Pump duration or fill times are off

In level fill systems, product will typically overflow from bottles and return to a holding tank. The pump must remain on long enough to allow the liquid to overflow into each of the individual bottles to achieve the fill level. A short duration pump can mean that not all bottles reach the desired level. The operator can usually perform a visual inspection during a fill cycle to ensure all containers reach level and overflow occurs. If not, the problem can be solved simply by adding some time to the pump duration of an overflow filler. As a side note, level fill system operators should also check to make sure overflow tubes are not submerged in liquid, which can create back pressure and play havoc with fill levels.

For volumetric fillers, each individual fill head can be programmed separately. This may simply mean that the nozzle can be opened for a set period of time, or that a set time is set for a pump “pulse” (for example, one turn, or a fraction of a turn, of a gear in the pump). . Please note that inconsistent filling on a volumetric filler does not mean varying levels in the bottles. Instead, it means that different volumes of product are dispensed from different bottles. Operators should check the volume of full fills to determine if volumes are inconsistent and then adjust the necessary fill heads as needed.

3. Product Path Connections

Automatic bottle fillers will draw product from a bulk tank or other supply, and some use a holding tank to supply product to bottles. The product will still travel through some path, through tubes and cylinders, to reach the containers. Packaging machinery operators experiencing varying fill levels on overflow fillers or varying amounts on volumetric fillers should check for product path leaks. The operator may not necessarily see the product from either connection. Loose clamps or tubes can allow small amounts of air to enter the track, creating inconsistent fill. Simply check and tighten all connections on the machine and run a test cycle to see if the problem is resolved.

4. Wear parts

Certain parts of liquid fillers will come into contact with the product, the bottles, or both. These and other parts can wear out and require replacement over time. On overflow or level fill fillers, special nozzles are used to create a seal in the bottle. These seals, along with the springs and o-rings, may need to be replaced from time to time. Visually inspect the nozzles to ensure that the bottle seal is sufficient, that the springs have not lost tension, or that there are other signs that parts need to be replaced. Some volumetric filler pumps and nozzles may also require replacement, and the same visual inspection should be performed on the volumetric liquid filler if fills become random or inconsistent.

5. Hold Fill/Supply Hold Functions

Automatic bottle filling machines will often include fill hold and supply hold functions in the operator interface setup menu. These functions can be activated and deactivated by the equipment operator. Generally speaking, the fill hold prevents the machine from starting a fill cycle while the supply tank is being replenished. On the other hand, supply hold prevents the equipment from replenishing the tank until the current fill cycle is complete. Make sure these features are turned on during production cycles if levels get random.

6. Bottles

Finally, while most bottles are manufactured so that each bottle is nearly identical to the next, some unique containers can vary greatly in internal volume. In those containers where the internal volume varies by a wide margin, volumetric fills can result in highly erratic fill levels. On the other hand, some packers who must achieve a volume range still choose to use a level fill system for aesthetic value. In these situations, packers should check the internal volume range on their bottles to ensure the fill level still falls within the acceptable volume range. While this issue is rare, those packers experiencing erratic fill levels will also want to inspect their bottles.

While the list above does not provide an exhaustive list of possible causes of inconsistent performance, the issues described above probably account for more than half of all erratic fill occurrences. For those who are unable to correct their level problem after reading this list, it is probably a good idea to contact your machinery manufacturer or a local service representative to discuss the problem further.