Thick-product dosing
Specify viscous-product filling around how the material moves, recovers, contains particulates, changes with temperature and releases from the nozzle.
Application review
Viscous and paste filling machinery should be selected from the product’s real flow behaviour, not a general viscosity label. The review should consider temperature, shear sensitivity, particulates, stringing, air entrapment, product supply, nozzle shut-off, container opening and the cleaning method required between batches.
A thick product may become easier to pump when warmed or sheared, then recover after filling. Another may contain particles that must pass through the product path without damage or blockage. Some products pull into strings when the nozzle closes; others trap air or continue to flow after the dosing movement stops. These behaviours affect the pump or piston principle, valve arrangement, nozzle geometry and the distance between the nozzle and container.
Product trials should therefore use material at the actual filling temperature and in the condition expected after mixing, transfer and holding. A cold laboratory sample may not represent a product supplied from a heated kettle, while a smooth surrogate cannot prove a recipe containing particulates.
Technology comparison
The correct principle depends on dose range, product behaviour and the wider production process. The table identifies questions to test rather than promising suitability without samples.
| Approach to assess | Potential strength | Application questions |
|---|---|---|
| Piston dosing | A defined displacement can suit many creams, gels, sauces and pastes. | Can the inlet and outlet valves pass the product and particulates? Does the cylinder clear and clean as required? |
| Positive-displacement pump | Controlled pump movement may support a range of liquid and viscous products. | Does the pump tolerate the product, shear condition and cleaning method? How is draw-back or shut-off controlled? |
| Pressure or product-transfer system | Assisted feed can help move products that do not fall reliably under gravity. | How is pressure stabilised, what happens at batch end, and can the supply system introduce air or temperature variation? |
| Heated product path | Temperature control may maintain products that thicken or set as they cool. | Which parts require heat, how is temperature monitored, and how will safe cleaning and shutdown be managed? |
Fill quality
The nozzle must fit the pack opening while allowing displaced air to escape. Bottom-up movement may be assessed where the product needs controlled placement, but the motion profile must avoid striking the container or drawing product across the neck. Shut-off design, suck-back and nozzle temperature can influence dripping and stringing, but they must be tuned using the actual recipe.
Supply conditions are equally important. A filler cannot compensate indefinitely for an upstream vessel that delivers an inconsistent head, introduces air, allows the product to cool or runs empty. The project boundary should identify who provides the feed pump, level control, heated hose, agitation and low-product response.
Buyer questions
There is no single best filler for every thick product. Piston or positive-displacement pump systems are often assessed, but the decision depends on flow behaviour, temperature, particulates, dose range, nozzle release, product supply and cleaning. A representative trial is the safest way to select the dosing principle.
Heated filling equipment may be needed when a product thickens, sets or becomes unstable as it cools. The review must identify which vessel, hose, pump, valve and nozzle areas need temperature control, together with safe shutdown, cleaning and restart procedures. Heating should follow the product process requirement, not be added by assumption.
Paste dripping or stringing can be reduced by matching nozzle geometry, shut-off action, suck-back, temperature and motion to the real product. Container position and fill height also matter. Changes should be proven with production material because a setting that improves one recipe may damage particulates or aerate another.
A paste filler may handle particulates only when the product path, valves, pump or piston, nozzle and dose can pass the largest representative pieces without blockage or unacceptable damage. The distribution of particulates between fills must also be checked, so trials need the final recipe rather than a smooth substitute.
