Filling accuracy describes how close delivered quantities are to the target, while repeatability describes how closely individual fills agree with one another under the same conditions. A process can be highly repeatable but consistently high or low, or average close to target while individual fills vary too widely. Both bias and spread must therefore be reported.
Accuracy asks whether the process is centred on the required quantity. Repeatability asks whether the process produces a tight spread when the product, machine and measurement conditions are held equivalent. A complete trial reports both.
| Term | What it describes | What the result may indicate |
|---|---|---|
| Target | The quantity the process is intended to deliver | The reference for setup and acceptance |
| Bias | The consistent difference between the process centre and the target | Set-point, calibration, density conversion or measurement issue |
| Repeatability | The spread between fills under equivalent conditions | Product, feed, valve, seal, air, nozzle or control variation |
| Accuracy | Closeness of results to the required value under the stated method | Combination of process centring and variation |
Yes. If every fill is close to the others but consistently above or below the target, the process is repeatable but biased. Correcting the setting may centre it, but the reason for the offset should still be understood—especially where density conversion, tare, product temperature or a head-specific calibration is involved.
Define the product, target quantity, measurement method, sample sequence and operating states before the trial. The test should include steady running and the transitions that matter in production, such as initial priming, product replenishment, a planned stop and restart, and any head or recipe change.
No. The product, dose, speed, number of heads, measurement method and operating condition must be stated. A figure obtained with one liquid cannot prove performance for a different paste, foaming product or particulate application.
Yes. Head identity shows whether variation is common to the process or local to one cylinder, valve, seal, hose, nozzle or setting.
Not on its own. Container wall thickness, shape and internal volume can make equal quantities appear at different levels. Quantity should be checked with an agreed measurement method.
There is no universal sample count for every risk and production system. The buyer should agree a sampling plan that covers heads, operating states and the applicable quality or legal requirements.
Recheck after product, temperature, density, cylinder, valve, seal, nozzle, recipe, speed or feed changes and after maintenance that can affect the dosing path.
Individual results with product condition, machine configuration, head identity, settings, measurement method, sample sequence and observed presentation provide more value than a headline percentage alone.
Send the product, pack, target quantity and acceptance method so Lancing can plan a test that reports both centring and variation.
