How do you calculate feeder rate compliance?

Divide off-target dose events by total dose cycles sampled, then subtract from 100% to get compliance. With 8 off-target events out of 250 cycles, the off-target rate is 3.2%, so compliance is about 96.8%.

What is a good feeder rate accuracy for loss-in-weight feeders?

Well-tuned LIW feeders typically hold better than 1% deviation at 2-sigma, meaning an off-target rate under 1-2% on tight tolerances. An off-target rate of 3.2% like the worked example suggests investigating refill disturbance or screw wear.

Why is my gravimetric feeder drifting off setpoint?

Common causes are refill-induced weight disturbances, material bridging or ratholing in the hopper, worn feed screws, and load-cell noise from vibration. A rising off-target count over successive runs usually points to mechanical wear rather than a control issue.

Feeder rate vs dosing accuracy — what's the difference?

Feeder rate compliance measures how often the feeder stayed on target across many cycles; dosing accuracy measures how close a single dose came to its target mass. Use rate for trend health and dosing accuracy for individual batch qualification.

How many cycles should I sample to judge feeder rate?

Sample enough cycles to cover at least several refill events, since refills are the biggest disturbance. A 250-cycle sample spanning multiple refills, as in the example, gives a far more honest rate than 20 cycles between refills.

Does a low off-target rate mean my feeder is calibrated?

Not necessarily. A feeder can be consistently on its own drifted setpoint, so a low off-target rate against a wrong target still yields bad product. Always confirm the setpoint itself against a static scale check.

Weighing, Dosing & Loss-in-Weight Feeding calculator

Feeder Rate Calculator

Feeder Rate here measures how consistently a loss-in-weight (LIW) or volumetric feeder hits its commanded setpoint, expressed as the share of dose cycles that landed on target versus the total sampled. Process engineers and line operators running gravimetric feeders on extrusion, compounding, and blending lines use it to quantify drift before it shows up as off-spec product. A feeder that logs 8 off-target events out of 250 cycles is telling you something about screw wear, bridging, or refill disturbance. Tracking this rate turns a vague sense that 'the feeder is acting up' into a number you can trend against a target and act on.

What this calculator does

Feeder Rate here measures how consistently a loss-in-weight (LIW) or volumetric feeder hits its commanded setpoint, expressed as the share of dose cycles that landed on target versus the total sampled.
Use it when feeder rate in weighing, dosing and loss-in-weight feeding needs a clean rate and gap-to-target you can put on a tier board.
It computes the fraction of feeder dose cycles flagged as off-target and the point gap between that fraction and your target compliance rate.

Formula used

Feeder Rate rate = affected amount ÷ total amount
Gap to target = target rate - calculated rate

Inputs explained

Off-target dose events:
Total dose cycles sampled:
Target feed-rate compliance:

How to use the result

Use it when auditing feeder performance from batch logs or a sampled run to decide whether recalibration, screw replacement, or refill tuning is warranted.
It treats every off-target event equally, so a single 30% overshoot counts the same as a 0.5% deviation; pair it with actual mass-deviation data before condemning a feeder.

Common questions

How do you calculate feeder rate compliance? Divide off-target dose events by total dose cycles sampled, then subtract from 100% to get compliance. With 8 off-target events out of 250 cycles, the off-target rate is 3.2%, so compliance is about 96.8%.
What is a good feeder rate accuracy for loss-in-weight feeders? Well-tuned LIW feeders typically hold better than 1% deviation at 2-sigma, meaning an off-target rate under 1-2% on tight tolerances. An off-target rate of 3.2% like the worked example suggests investigating refill disturbance or screw wear.
Why is my gravimetric feeder drifting off setpoint? Common causes are refill-induced weight disturbances, material bridging or ratholing in the hopper, worn feed screws, and load-cell noise from vibration. A rising off-target count over successive runs usually points to mechanical wear rather than a control issue.
Feeder rate vs dosing accuracy — what's the difference? Feeder rate compliance measures how often the feeder stayed on target across many cycles; dosing accuracy measures how close a single dose came to its target mass. Use rate for trend health and dosing accuracy for individual batch qualification.
How many cycles should I sample to judge feeder rate? Sample enough cycles to cover at least several refill events, since refills are the biggest disturbance. A 250-cycle sample spanning multiple refills, as in the example, gives a far more honest rate than 20 cycles between refills.

Last reviewed 2026-05-12.