The Inner Workings of the Piston Filling Machine

The Inner Workings of the Piston Filling Machine

Piston filling machines are an incredibly versatile type of filler in that they can handle products both thick and thin, including products with particulates or chunks (think tomato paste or jams and jellies with pieces of fruit).  Given the principle behind the piston filler, they also offer a highly accurate volumetric fill.  These two attributes alone can make a piston filler the ideal filling machine for a great number of packaging projects.  Below we will take a quick look at the piston filling principle to show how these attributes are attainable.

The piston filler uses - no big surprise here - a piston, to move product from a supply tank to the waiting bottles and containers.  In general, the piston will retract from the cylinder, allowing the cylinder to fill up with product.  The actual length that the piston will retract can be adjusted by the operator of the filling machine.  However, once that retraction point is set, each cycle will bring the same amount of product into the piston filler cylinder.  Once product fills the cylinder, the piston will move forward, pushing product out of the cylinder, through a combination of tubes and/or nozzles, and into the waiting containers.  Since the retraction point of the piston is the same each cycle, and the end point or push point of the piston is the same each cycle, the same volume of product will enter and exit the cylinder each cycle, giving the piston filling machine its reputation as an accurate liquid filler.

Also, the volume will remain the same inside the piston cylinder whether a product is thick or thin.  There is nothing relating to the product being filled that should change the volume that is entering the cylinder when the product retracts.  Even when we talk about tomato pastes and jams and jellies with chunks of product, the piston itself will remain pretty much unchanged.  When dealing with product chunks, however, there may be some unique aspects to the liquid filler as a whole.  The piston cylinder will be large enough to handle the chunks, but keep in mind that some adjustment may still need to be made as the entire product pathway must accommodate these pieces.  Therefore, large tubing or special nozzles may be necessary to ensure that both the liquid product and the chunks make it to the bottle or container without lodging along the pathway and blocking the filler.  The tank may also require an agitator or other type of mixer to make sure that the solids in the product do not settle on the bottom, also stopping the product from filling correctly.

Piston filling machines can be manufactured as tabletop, semi-automatic and automatic liquid fillers.  Each level of automation includes easy to use controls and adjustments, from simple finger switches to PLC based touchscreen interfaces.  Whatever the automation level, these filling machines often offer the ideal solution for a wide range of products and industries.

For more information on piston fillers, click here.