Fill accuracy on a vertical bagger comes from the dosing head, not the bagger. Fine powders need an auger; free-flowing granules suit volumetric cups; product with variable density needs a weigher; liquids and pastes need a pump. Choosing by price rather than product is the usual cause of weight giveaway.
Four dosing systems and what each is for
| System | Suits | Weakness |
|---|---|---|
| Auger filler | Fine powders, flour, milk powder, spices | Slower; abrasive products wear the screw |
| Volumetric cup | Free-flowing granules, rice, sugar, seeds | Accuracy drifts with bulk density |
| Multi-head weigher | Variable density, mixed shapes, snacks | Higher cost and footprint |
| Piston or pump | Liquids, pastes, sauces | Needs cleaning regime; viscosity sensitive |
Why volumetric filling drifts and weighing does not
A volumetric cup measures volume and assumes density is constant. Change the moisture, the particle size or the settling and the same volume weighs differently — so you either overfill to stay legal or risk underfill. A weigher measures the actual weight of each dose, which is why it is specified where density varies.
Give-away is a cost, not a rounding error
If a line overfills by two percent to guarantee minimum weight, that is two percent of material cost every shift, forever. Comparing dosing systems on purchase price alone usually ignores the recurring cost of the give-away the cheaper head forces you to accept.
Across the 4 filling and dosing series and 13 vertical packaging series we list, electronic weighing, granule filling, piston and weighing configurations are published separately so the head can be matched to the product.
Dosing heads are listed in the filling and dosing range; bagging platforms in the vertical form-fill-seal range.
Figures in this article are drawn from the 137 machine series SilverSeal currently supplies, not from generic industry averages. Specifications vary by model — check the individual series page before specifying.
Frequently asked questions
Can I change the dosing head later?
On most platforms yes, but confirm the mounting and control interface before buying. It is much cheaper to specify it correctly at order.
What accuracy can I expect from a volumetric cup?
It depends entirely on how consistent your bulk density is. For a stable free-flowing granule it is good; for anything variable, a weigher is the answer.
Does a weigher slow the line down?
A multi-head weigher is designed to keep pace with a bagger. A single-head weigher is slower than a cup filler.
