Guides and side belts
Adjustable rails and belts centre the jar and resist rotation while maintaining continuous flow.
Container control
How are jars stabilised during automatic capping?
Jars are stabilised with format-appropriate guides, side belts, clamps, pockets, star wheels or controlled conveyor geometry so the closure can be applied without the container rotating, tipping or being damaged.
Use representative evidence. The correct method depends on the container material, shape, base, label area, product level and closing force.
Handling methods
Match the restraint to the container and closing action.
Pockets and star wheels
Dedicated geometry controls pitch and position for indexed or rotary handling, often with format parts.
Clamps or nests
A fixed support can suit semi-automatic or indexed operations where the jar is held during the closing cycle.
Why do jars rotate, tip or drift during capping?
Jars move when the applied closing force exceeds the restraint provided by the conveyor, guides or container contact, or when the jar enters the closing zone off-centre.
High centres of gravity, uneven bases, low product weight, slippery surfaces, conveyor pressure and nearby jars can increase instability. Observe the point where movement begins rather than correcting only the final misapplied lid.
Also check the infeed spacing and line-control design.
How is the right jar-stabilisation method selected?
Selection starts with the actual container and the force path created by the chosen capping head, then balances grip, support, access, marking risk and changeover.
A cylindrical rigid jar may suit side belts, while an irregular or unstable container may need a pocket or nest. The trial should include normal dimensional variation, filled weight, labels or decoration and the intended conveyor condition.
Include every format in the jar and lid compatibility matrix.
How does stabilisation differ for glass and plastic jars?
Glass generally resists squeezing but needs protection from impact and point loading; lightweight plastic may deform or buckle if restraint pressure is too high.
Both materials can scuff or tip. Use compliant contact materials and settings proven on finished packs, and consider product temperature because hot containers may behave differently from room-temperature samples.
See the dedicated glass jar and plastic jar guidance.
What should a trial prove about jar handling?
A trial should prove repeatable entry, centring, restraint and release across normal running, starts, stops, back-pressure and the approved format range.
Record tipping, glass contact, deformation, scuffing, label damage, spill contamination and any manual correction. The accepted setup should include guide positions, pressure settings, format parts and first-off checks so it can be reproduced after changeover.
Build these observations into the FAT and SAT plan.
Compare jar support using a documented movement sequence
Observe the jar at entry, during lid application and after release. Note whether a movement begins before the capper, under the head or at the next transfer. Keeping those stages separate helps an equipment discussion focus on the restraint or transfer that actually needs attention.
Use the same labelled jar formats when comparing alternative handling arrangements. Include changes in filled weight, decoration and base geometry that your production range already contains. A successful demonstration on one stable jar should be recorded as evidence for that format, rather than assumed to cover the full range.
- Position record
- Capture the jar reference, entry orientation and observed movement with a short safely obtained video or still sequence.
- Surface review
- Identify label edges, seams and decorated faces that may affect or limit the proposed support contact.
- Exit check
- Examine whether the jar leaves the closing station in a condition suitable for the next conveyor or inspection stage.
Should restraint be assessed only while the cap is being tightened?
No. Include entry and release; an unstable transfer can remain a problem even when the closing position looks correct.
How should handling changes be recorded?
Associate the approved format, tooling arrangement and observed result with the same revision of the trial record.