What is a Piston Filling Machine?

A piston filling machine is used to fill a number of different types of products, including high and low viscosity liquids.  The piston filler will often be used for food-grade products and can even handle products with particulates, such as salad dressings, jams, or jellies.  At Liquid Packaging Solutions, both semi-automatic and automatic piston filling machines are manufactured for a variety of products both thick and thin.

The five main parts of the piston filler are:

• The Hopper
• The Valve
• The Cylinder
• The Piston
• The Nozzle

As product sits in the hopper, the valve, which sits between the hopper and the nozzle, will be open from the hopper to the cylinder. The piston will begin to withdraw from the cylinder, typically after an operator activates the fill by stepping on a foot switch. As the piston withdraws, product from the hopper will fill the empty cylinder. Once the piston has withdrawn to the desired point, the valve will rotate to allow product to move through the nozzle. At this point the piston push back in to the cylinder and move product through the nozzle and in to the waiting bottles or other containers. This process creates a highly accurate volumetric fill as the interior volume of the cylinder will never change, meaning the volume of product released to the bottles will never change.

The hopper sizes can vary from project to project based on the size of the containers or fills. Not all piston filling machines, and in particular, the automatic piston fillers, will use a hopper from which to pull product. Automatic lines will likely include a tank or pull from a bulk source. The cylinder and piston combination are also available in different sizes to accommodate different projects. The speed with which the piston moves can be adjusted, different piston sizes can be used to meet volume requirements and even multi-piston, automatic filling machines can be designed for use with inline packaging systems. LPS piston fillers allow the operator to adjust the length of the piston stroke, which in turn adjusts the volume of product that is pulled in to the cylider with each fill cycle. This way a single piston size can handle a range of container sizes. While multiple strokes of the piston can also be used for larger fills, at some point the efficiency of using multiple strokes will become low enough that simply changing out the piston for large containers will be the better solution.

The nozzle used on any piston filler will be chosen to meet the needs of the particular project at hand. For instance, a product with large chunks of fruit or vegetables will not work well if a narrow nozzle is used to move product in to the bottles. On the other hand, a very large nozzle will be cumbersome with a small mouthed bottle. There is virtually no limit to the type of nozzles that can be used, including custom manufactured nozzles where special projects are concerned.

Though a simple concept, the piston filler can be an ideal solution for many projects and for liquids thick and thin. Though these machines are known for handling viscous products, in the right circumstances they will handle free-flowing liquids as well. For assistance finding the best type of filling machine for your own packaging project, contact Liquid Packaging Solutions today.