Why can fill weight drift when the cup setting has not changed?
Bulk density, moisture, particle distribution, hopper level, vibration or aeration may have changed. The cup still measures the same nominal volume.
Dry product dosing
How does bulk density affect a volumetric cup filler?
A volumetric cup filler measures a fixed or adjustable volume, so the delivered mass changes when the product’s bulk density or the way it settles in the cup changes. Target cup volume is approximately target mass divided by representative bulk density. The product must therefore be tested across the normal loose, settled, aerated and moisture conditions expected in production.
Bulk densityCup volumeGranulesWeight variation
Direct answer
The cup controls volume; bulk density determines the resulting mass.
Two batches can occupy the same cup volume but produce different weights when particle size, moisture, aeration, settling or handling changes the mass per unit volume. A reliable cup-filler specification starts with measured bulk-density variation rather than one catalogue weight.
- Measure representative loose and settled product conditions.
- Record moisture, particle size, vibration and feed method.
- Choose a cup range that covers the target without an extreme setting.
- Trial startup, hopper refill and steady production.
Density variation
What can change bulk density during cup filling?
| Changing condition | Effect on the cup | Evidence to record |
|---|---|---|
| Particle size distribution | Smaller particles can occupy gaps between larger pieces | Representative batch and segregation condition |
| Moisture or oil | Changes adhesion, flow and mass per volume | Product condition and storage history |
| Aeration | Loose product can occupy more volume before settling | Feed, vibration and dwell time |
| Vibration or compaction | Can increase the mass in a fixed cup | Vibration setting and cup-filling method |
| Hopper level and refill | Can alter head pressure and the way product enters the cup | Level, refill event and sequence position |
Buyer question
Can a volumetric cup filler guarantee a target weight?
A cup filler can produce repeatable mass only to the extent that the product occupies the cup consistently. When bulk density varies materially, a fixed cup can deliver different weights. The buyer should define the acceptable range, test representative product conditions and compare a weigh filler when direct mass feedback is required.
Measure more than one scoop. A single hand-filled cup does not prove the automatic feed, levelling, vibration and discharge conditions of the machine.
Trial method
How should a cup-filler bulk-density trial be run?
Use product from the real supply route and measure the mass delivered by the cup across startup, normal running, hopper refill and any condition that changes settling or segregation. Record cup setting, vibration, speed, product condition and individual results.
- Collect representative product, including normal fines and larger pieces.
- Measure loose and process-conditioned bulk density using a consistent method.
- Calculate an indicative cup volume, then select the practical cup or adjustment range.
- Run the intended automatic feed and levelling process.
- Compare individual mass results and observe blocks, bridging, damage and segregation.
Common questions
Questions about cup fillers and bulk density
Does vibration always improve cup-filler accuracy?
No. Vibration can stabilise feed for one product but compact or segregate another. The setting must be trialled with the real product.
How should bulk density be measured?
Use a consistent container, fill method and levelling method that represent the process condition, then record mass divided by known volume. Keep loose and settled results separate.
When is a weigh filler the stronger choice?
Consider direct weighing when sale quantity is controlled by mass, density varies widely, the product is irregular or the permitted mass variation is tighter than cup dosing can demonstrate.
Can one cup cover a very wide quantity range?
Not always. Extreme adjustment can reduce control or change how product settles. The range should be checked against practical cup sizes and change parts.
Which samples should be sent for a cup-filler trial?
Send enough material to represent normal production, including expected fines, larger pieces, moisture variation and the supply condition after transport and storage.
Related guidance
Compare cup dosing with alternative dry-product methods.
Send representative dry product, not only a target weight.
Lancing can compare cup, auger and weigh routes after reviewing flow, bulk-density variation, particle size and the intended pack.