Lancing Ltd · Published · General selection guidance; final suitability requires application review.
Separate the dosing decision from the inspection decision
| Equipment or check | Primary role | Important boundary |
|---|---|---|
| Volumetric filler | Dispenses a configured volume using its dosing principle | Verify the delivered result with the actual product and conditions |
| Net-weight filler | Uses a weighing signal while dispensing | Define how tare, cut-off and settled weight are handled |
| Downstream checkweigher | Measures packs after the preceding operations | The reading includes packaging present at the weighing point |
| Bench quantity check | Provides defined sampled verification | Requires a suitable method, tare procedure and sampling plan |
| Feedback connection | Uses measured trends to request a bounded filling adjustment | Not an automatic cure for wrong tare, pack mix-ups or mechanical faults |
The METTLER TOLEDO checkweighing guide distinguishes gross measurement from fill weight where container tare varies. Apply that distinction before selecting an instrument or setting acceptance limits. An accurate gross reading can still be a poor estimate of net contents if packaging variation is not addressed.
An illustrative tare example
Suppose a finished bottle weighs 522 g and the complete empty pack weighs 22 g. Its calculated net product is 500 g. A second pack weighing 522 g with a 27 g tare contains 495 g. The gross readings match, but the calculated contents differ. These are arithmetic examples, not Lancing performance figures, legal limits or suggested production settings.
Identify what is included at each weighing point: bottle alone, bottle plus cap, or the finished labelled pack. A mean tare from samples and an individual tare measurement are different methods. The choice needs to reflect packaging variation and the accuracy required by the quality procedure.
Place the check where its result is meaningful
Review the conveyor transfer, bottle spacing, wet surfaces and the time available for a stable measurement. Define whether bottles arrive open or capped and whether other equipment affects the measurement. Decide where rejected packs go and how rejected, missing or uncertain results are recorded.
A rejection should be demonstrated with representative test packs under the supplier’s safe procedure. Confirm detection, physical rejection, reject confirmation and the response to a reject-system fault. A display changing colour is not the same as proving the suspect bottle cannot continue with accepted production.
Treat feedback as a controlled interface
A checkweigher may feed an adjustment signal back to a compatible filler, but the two systems must share a defined control plan. Specify the product recipe, target basis, valid measurement states, averaging period, adjustment bounds, authorisation and response to a fault. METTLER TOLEDO’s feedback explanation describes trend-based correction rather than adjustment from every individual bottle.
Discuss how delayed samples are associated with a change in filler setting. Disable inappropriate corrections during startup, bottle-format changes, missing closures or suspect measurements according to the agreed control design. If nozzle-level correction is required, confirm that the line can identify which head produced the bottle; do not infer that capability from the presence of a checkweigher.
Agree legal quantity and process acceptance separately
UK packaged-goods requirements depend on the applicable system and product. GOV.UK’s packaged-goods guidance explains minimum and average approaches and the need for suitable checks. Ask the responsible quality team or Trading Standards adviser to confirm the applicable method and instrument requirements. Buying a filler or checkweigher does not itself certify compliance.
For machinery acceptance, define the test product, tare method, fill targets, sampling sequence and measurement equipment. Include the lowest and highest normal fills, planned pauses and restart results. Use the fill-verification guide for the dosing evidence and keep the inspection-system challenge record distinct.
Information needed for a linked filling and inspection quotation
- Nominal quantity and whether it is specified by mass or volume.
- Bottle and closure samples with observed packaging-weight variation.
- Where the bottle is weighed and what packaging is present at that point.
- Required accepted output, conveyor layout and bottle spacing.
- Reject handling, fault response, reporting and any proposed feedback.
- The instrument and verification requirements agreed by the responsible quality team.
Compare net-weight filling with other dosing methods first, then define inspection as part of the complete bottle line.