Liquid filling machines can use a number of different principles to get product from a supply tank to the waiting bottles or containers. Each filling principle offers unique advantages or benefits. For example, an overflow filler is ideal for products packaged in clear containers because each bottle is filled to the same exact level, creating a pleasing shelf presence. While the piston filler does not use unique nozzles to fill to the same level each cycle, it does allow the packager an accurate volumetric fill with each fill cycle.
The name of the filler itself is descriptive of the detergent filling machine. The piston filler uses a piston to pull product into a cylinder, then push that same product into the bottles or containers. As the piston retracts from the cylinder, product enters the cylinder. The end point for retraction can be set by the operator of the machine. As long as the end retraction point is not changed, the same volume of product will enter the cylinder during each fill cycle, or each retraction of the piston. Once the product is in the cylinder, the piston will reverse directions and force the product out of the cylinder, through the product pathway and into the containers.
Since the same amount of product enters and exits the cylinder during each retraction and return of the piston, the volumetric accuracy of the fill will be high when using a piston filling machine. A highly accurate fill, by itself, can increase the bottom line for a packaging company. At first glance, this may not be entirely obvious, but consider a company that packages shampoo in a 10 ounce container. If the company packages 10,000 bottles per day, they would reach 50,000 bottles by the end of the week. Now assume that the filling machine used was inaccurate, averaging 10.5 ounces of product in each bottle. This means that for every 20 bottles filled, the company is giving away an extra 10 ounces of product, or one free bottle. If you continue to expand the math, this shampoo company is giving away over 125,000 bottles per year, simply because the filling machine being used does not provide an accurate volumetric fill. That number can have a significant impact on the company bottom line! The example is somewhat extreme, but even at a fraction of an ounce, it is clear that the lost profits add up over the years.
As noted, the piston filler accuracy alone can save a company money and increase profits, but it is not the only benefit of using this type of liquid filler. Piston filling machinery can be manufactured for low to high production projects. A simple tabletop filling machine may be used for a start up company or for companies with a local or regional market and lower production demands. Automatic piston fillers can be used on inline packaging systems to fill thousands of bottles per hour. These filling machines can also handle a wide range of products, from thin, foaming liquids to thick, viscous products like pastes, gels and jams. In addition, the piston filler is usually the ideal solution for products that include large particulates or chunks, such as jams with fruit, tomato sauce with actual tomato chunks and other similar products. The ability to handle products thick and thin can also make the piston filler an ideal solution for companies that package numerous and varying products.
If volumetric accuracy is the key, the piston filler will usually be the ideal choice. Keep in mind, though, that each type of filling machine has advantages and benefits that are unique. Each and every packager should weigh the benefits of each filling principle before deciding on which is best for their own unique project.