One major aspect of choosing the correct machinery for any packaging project is understanding the speed necessary to meet production needs. Filling machines, capping machines and other equipment will be extremely de-valued if they simply do not produce enough product to fill customer demand. In the packaging industry, the speed of a machine is most checkweigher machine often described by bottles per minute (bpm) or sometimes pieces per minute (ppm). In determining bpm, a number of different factors, such as the product, bottle sizes, cap type or size and indexing type, will be considered to figure the speed.
In other words, a packaging machinery manufacturer cannot simply say a certain machine will fill or cap 50 bottles per minute. This determination requires some insight into the actual project. As an example, consider a company that is looking to fill a liquid product using an automatic filling machine. Before a manufacturer can tell that packager how many bottles per minute a machine will run, they must know what product or products will be run as well as the size of the containers that will be filled. In addition, the manufacturer will also need to know about how many bottles a company wants to produce. Once this information is gathered, determining the speed of the machine is really nothing more than a mathematical equation.
If our fictitious packager is filling only 16 ounce bottles of one free-flowing liquid, and needs to package about 10,000 bottles in an eight hour shift, we can use these numbers to both find the ideal filler and determine the speed necessary to reach the production goals. First, we would divide the number of bottles by the number of hours in a day (10,000 bottles/8 hours). This gives us a total of 1,250 bottles that the packager needs to prepare each hour. Then we can divide the number of bottles per hour by the number of minutes in each hour (1,250 bottles/60 minutes in an hour). The result tells us that the packager needs to fill between 20 and 21 bottles each minute.
From here, the math turns to the performance of the machine. The time that it takes the machine to cycle must be determined to ensure that the 20 to 21 bpm can be met. A fill cycle, however, does not simply translate to the time it takes to fill the bottles. Bottles will be delivered to an automatic filling machine via a conveyor system. Bottles must index in and out of the fill area. In addition, time may be added for fill heads to dive and rise, for a fraction of a second for neck grabbers to stabilize bottles or for a variety of other functions. Adding all of these times to the fill time gives us a cycle time. The cycle time will run from the time the indexing gate opens to allow bottles into the fill area right up until that same gate opens to allow the next set of containers access.
In our example, using a four head filling machine with a ten second fill cycle means the machine will complete six cycles each minute. Six cycles of four bottles per minute gives our packager about 24 bpm, which meets the current production demand. But what if the company procures more contracts or the popularity of the product grows? Many packagers may opt for a six head filling machine which would produce 36 bpm to allow for short-term growth. Additionally, a majority of packaging machine manufacturers will build the machinery to allow for the addition of fill heads in the future, letting the equipment grow with the company. While the analysis may depend on different components for different machinery, the math will basically remain the same. Determine the bpm necessary, identify the machine that will meet that need and consider room for growth. While somewhat simplified, these steps should always be taken to ensure the best machine for the project will be built and employed.