Liquid Filling Machines - Doing the Math

Liquid Filling Machines - Doing the Math

One of the many questions that may come up when discussing a liquid filling machine is the number of bottles per minute that can be run on the machine.  While bottles per minute seems like a simple concept, it can often be confused with fill time or total production.  Bottles per minute is not the same number as total production.  The simple fact that a liquid filling machine can run 60 bottles per minute does not mean that you will produce 60 completely packaged bottles or containers each minute.  Remember that the speed of a packaging line will always be reduced or limited by the slowest piece of packaging equipment on that line.  A labeling machine, for example, may not be able to keep up with the filling equipment if the labels are large or applied in a unique manner.  For this article, we will be discussing bottles per minutes as it pertains to liquid filling machines, as opposed to complete packaging lines.

Let's do a quick equation to show how we reach the bottles per minute figure for a liquid filler.  Assume that we have a ten head overflow filling machine.  The overflow filler will move ten bottles under the fill heads, fill each bottle and move them out of the fill area in fifteen seconds.  This is known as a fill cycle, basically the indexing time plus the fill time.  At fifteen seconds a cycle, the overflow filler will complete four cycles per minute.  Ten bottles per cycle times four cycles per minute means that this particular filling machine will run forty bottles per minute.  Keep in mind that the fill time for the machine is also not the same as the cycle time or the bottles per minute.  The fill time is simply a component of the cycle time, and the cycle time is used to compute bottles per minute.  To further illustrate this point, we will break down a single fill cycle to show the total time.

Returning to our overflow filler from above, we will assume that the automatic filling machine uses pin indexing.  Pin indexing consists of two pins or gates.  An entry gate opens to allow empty bottles to move into the fill area and under the fill heads, the exit gate would be closed at this time to keep bottles positioned under the fill heads.  The fill cycle would begin when the entry gate opens to allow bottles to enter the fill area.  Once the gate opens, two seconds elapse until the bottles are positioned under the fill heads.  A one-half second delay then occurs until the fill heads dive into the bottles. It takes one second for the fill heads to dive.  Another half-second delay occurs and the fill begins.

Now, near the middle of the fill cycle, we finally reach the fill time.  The actual fill time for the bottles in our sample is eight seconds.  This is the amount of time that the pump will run and product will be dispensed into the bottles.  Once the fill is complete, another one-half second delay occurs before the heads emerge from the bottles and retract upward.  A final half second delay occurs before the exit gate opens and the filled bottles move out of the fill area, taking another two seconds.  Add all these seconds and half-seconds together and you will find that we have successfully broken down our fifteen second cycle time, of which eight seconds are fill time.  

If you are shopping for a liquid filler, you may also hear the terms delay times and duration times.  Delay times are pauses prior to some action taking place.  For example, the head dive above is delayed for one-half second.  This delay time avoids spills and inaccurate dives by ensuring the bottles are in place and stabile before the heads lower.  Delays also occur prior to the opening and closing of the indexing gates.   Duration times refer to how long a certain task continues.  The eight second fill time noted above is a duration time - the action of filling continues for eight seconds.  Based on the type of filling machine being used, it is these specific delay and duration times that, when connected, make up the fill cycle.  

Though this is a brief summary of the bottles per minute calculation on a liquid filler, hopefully it will help the reader to understand the difference between fill cycle time, fill time and bottles per minute.  For additional questions regarding liquid filling equipment, contact a Packaging Specialist at Liquid Packaging Solutions toll free today at 1-888-393-3693!