The Inner - and Outer - Workings of an Automatic Overflow Filler
Overflow filling machines are unique in that they fill bottles to a specific level in each bottle, even if the interior volume from one container to the next varies slightly. This type of fill benefits those packagers that are using a clear container, be it glass or plastic, both aesthetically and as to consumer confidence. But how does this liquid filler achieve the same level in each container both consistently and reliably in an automatic manner? Below we explain some of the components of the overflow machine that makes the unique and automatic fill possible.
In general the level fill is achieved by recirculating liquid through the product pathway. Special nozzles used on any overflow filling machine first dive in to the bottle and form a seal over the bottle opening. As the nozzle dives and seals, the product is released in to the bottle. Once the liquid reaches the desired level, the product flows through a return port back to the holding tank. Though other methods are available, the nozzles will typically use spacers to achieve the desired fill level. These spacers can be adjusted to change the level for different containers.
To make the level fill work automatically, however, the nozzles need a little help. Automatic filling machines are controlled by a PLC that sends signals to the different components of the machinery to ensure they perform their tasks in a timely manner. For an automatic overflow filler, the correct number of bottles must first be in position under the fill heads before the fill can begin. A sensor will read bottles as they enter the fill area, sending a signal to the PLC when the bottles are in place. From here, the PLC takes over, telling indexing gates when to open and close, heads when to dive, the pump when to turn on and off and various other functions that may change slightly from machine to machine.
As an example, imagine bottles traveling down a conveyor system. As they pass the first sensor, they are "counted" as they enter the fill area, stopping at the exit gate, which is closed. Once the correct number of containers are counted, the PLC send a signal to close the entrance gate of the indexing system, stopping more containers from entering or back pressure from causing the bottles to move. After a delay, the PLC will signal the heads to dive in to the containers. Another delay will ensue before the PLC signals the pump to start pushing product in to the containers. At this point, the PLC will also time the fill, again signaling when the pump should turn off to complete the fill. More delays will be timed by the PLC before signals are sent to raise the fill heads, open the exit gate and allow the filled bottles to continue down the power conveyor system.
While all these delay and duration times might sound like a daunting set up, the PLC of an overflow filler also allows all the settings to be saved for simple recall when the machine is ready to run production. At the most, operators will need to find the proper times on one occasion, though in most cases the machine will come pre-set will all of the necessary delay and duration times.
So unique nozzles coupled with precise delay and duration time controls through the PLC of an overflow filler allow the machine to consistently fill containers to the same level with each fill cycle. To learn more about other filling principles used on LPS equipment, simply browse the Filling Machinery section of the website or contact a Packaging Specialist at LPS today.