When filling free flowing liquids, gravity may be enough to move the fluid from a tank to the bottles. However, thicker products, such as honey, jams, putty and even motor oil, may need a little encouragement to slide in to waiting bottles. Varying degrees of viscosity are one of the reasons that a number of different filling machines exist. And different machines are built to handle different viscosities. Both pump fillers and piston filling machines will typically be seen in projects that involve thick liquids, though exceptions do exist.
Pump filling machines, quite simply, use a pump to move product through a pathway and in to the bottles. Liquid will be pulled from a bulk source or tank and the pumps are used to meter out the product based on time or pump movement (pulse). While assisting with dispensing the correct amount of product, the pumps also move thicker products that might not flow from a raised tank, or at the very least would not flow fast enough to make the machine an efficient investment. Pump fillers can be manufactured to handle small and large production runs on frames suited to the project, from tabletop to portable full frame machines with multiple fill heads. An added benefit of pump filling machines is the ability to choose the pump that is the best fit for any given project, from peristaltic pumps to avoid cross-contamination to handling particulates like cherries and other fruits in jams without crushing them.
Piston filling machines will pull product into a cylinder and disperse it with the help of the piston. Piston fillers work with thick products by using suction to pull product into the cylinder when the piston retracts. To fill the bottles, the piston will then push product out of the cylinder and in to waiting containers. Like above, the "flow" of thicker products will receive assistance, in this case by the movement of the piston in and out of the cylinder. Piston fillers are also ideal for thick products like jams and sauces that may contain food particulates both small and large, as the cylinder allows for a larger open area for the product.
Both pump fillers and piston fillers provide good options for high viscosity products, though one may be better suited for a given project based on other factors such as bottles, products, speed and more. To discuss your own project and filling machine options with a Packaging Specialist, contact NPACK today!