Plastic banded cap
The cap arrives with its thread and band already formed.
The capping machine starts and tightens the pre-threaded cap. The bottle finish and band geometry determine how the band travels over and retains beneath the neck bead.
Tamper-evident screw closures
Tamper-evident banded screw cap capping.
Specify plastic breakaway-band screw caps around the cap, neck finish, bridge condition, seating and opening check.
Closure definition
Treat the cap, breakaway band and bottle finish as one package.
A tamper-evident banded screw cap is normally a pre-threaded plastic closure with a frangible band below the cap skirt. During application the cap screws onto the bottle while the band passes or engages the neck bead. On first opening the bridges are intended to break in the designed way. The capper must seat the closure without prematurely damaging the band, threads, liner or bottle finish.
Different process
ROPP forms an aluminium closure on the bottle.
ROPP uses rollers to form the thread and pilfer band from an aluminium shell. It requires different heads, neck-finish evidence and inspection from a pre-threaded plastic screw cap.
Compare ROPP and screw capping →Separate component
A shrink band or sleeve is not applied by the capper.
A separate tamper-evident sleeve is applied and shrunk around an already closed pack. It should be planned as a separate packaging stage with its own material and process checks.
Application sequence
Control thread start, band travel and final seating.
- Present the cap squarely.
The closure should reach the bottle in the intended state without a tilted thread start, open hinge or damaged band. - Support the bottle.
The bottle must resist the application forces without turning, buckling or moving away from the capping head. - Start the thread cleanly.
Guides, cap placement and head contact should allow the cap and bottle threads to engage without cross-threading or shaving material. - Allow the band to pass the neck bead.
The band, retaining features and bottle bead must be compatible. Excessive interference or damaged components can break bridges during application. - Reach the agreed seating condition.
Use the closure supplier's packaging guidance and the buyer's quality method to define cap height, liner compression, torque or another functional check. - Verify first opening.
Retain samples and confirm that the tamper feature behaves as intended after the relevant conditioning and storage period.
Troubleshooting
Use the finished cap position to separate likely causes.
| Observed result | Possible evidence to examine | Controlled next check |
|---|---|---|
| Band bridges break during capping | Cap batch condition, neck bead dimensions, cap angle, band contact and application setting. | Compare unused caps and bottle finishes, then run one controlled adjustment at a time. |
| Cap sits high | Thread start, liner or seal stack, cap/bottle mismatch, band interference and product on the finish. | Compare cap height and thread engagement on accepted and rejected packs. |
| Band does not retain after opening | Band geometry, bottle bead, slit or bridge design, application depth and component variation. | Refer to controlled closure and bottle drawings and involve the component suppliers. |
| Cap spins without tightening | Stripped threads, cap or neck damage, poor engagement, bottle rotation or unsuitable tooling. | Stop increasing the setting and inspect both threads before another trial. |
| Cap leaks but band appears correct | Liner, sealing surface, product contamination, cap seating and storage condition. | Use the agreed leak and opening method; tamper evidence alone does not prove the seal. |
Buyer questions
Questions about plastic tamper-evident screw caps.
What is a tamper-evident banded screw cap?
It is a pre-threaded closure with a lower band connected to the main cap by designed bridges. The band is intended to engage the bottle finish during application and provide visible evidence on first opening. The exact bridge, slit and retention design belongs to the closure specification.
How is a plastic tamper-evident screw cap different from ROPP?
A plastic banded cap already contains its thread and tamper feature, whereas an aluminium ROPP closure is formed onto the bottle by rollers. The machine heads, neck-finish checks, cap presentation and inspection method are therefore different even though both packages can provide tamper evidence.
Review ROPP capping →Why can a tamper-evident band break during capping?
Premature breakage can result from damaged or variable caps, excessive interference with the neck bead, tilted application, incompatible components or an unsuitable machine setting. Retain unused caps, failed packs and bottle samples from the same batches so the closure, bottle and machine causes can be separated.
Why can a banded screw cap sit too high on the bottle?
A high cap can indicate incomplete thread engagement, a mismatched neck finish, liner or seal-stack interference, product on the sealing surface, band contact or a cap that has not reached the agreed seating condition. Do not correct it by increasing force until the pack components have been checked.
Which checks confirm a correctly applied tamper-evident screw cap?
Use the packaging specification to define cap height, alignment, liner or seal function, opening behaviour and the condition of the band and bridges. Torque may be one check, but it should not replace visual, leak or first-opening evidence where those functions matter.
Define the closure-quality method →What samples and drawings are needed for a banded-cap trial?
Supply production bottles and closures from normal batches, current drawings or references, accepted and failed packs, product or representative fill details, target output and the finished-pack test method. Include the smallest, largest and least stable formats in the proposed range.
Prepare trial samples →Evidence before specification
Confirm the complete tamper-evident package.
Send production caps, bottles, drawings where available, failed examples and the quality method used after capping and first opening. Lancing can use that evidence to screen the screw-capping route and trial requirements.