Cap and liner sample trial plan for induction sealing
Use this guide to prepare representative packaging samples before confirming an induction sealer, sealing head or final quotation.
What should be supplied for an induction sealing sample trial?
A useful induction sealing trial needs the complete cap, foil liner and container system, not only an empty bottle or a cap diameter. The machine heats the foil layer, but the final seal depends on how the cap holds the liner against the container mouth and whether the heat-seal layer is compatible with the packaging material.
For each format, send production-intent samples where available. If filled product cannot be supplied, provide a safe representative sample and explain how the real product differs. Product residues, oils, powders and foaming liquids can all change what the operator sees at the neck finish, so the trial note should make that context clear.
| Trial item | Why it matters | What to label |
|---|---|---|
| Container | Material, mouth flatness and bottle stability all affect seal quality and conveyor handling. | Material, fill state, height, mouth outside diameter and any supplier reference. |
| Cap | The cap provides pressure while the liner bonds and cools. | Cap diameter, thread or fit type, supplier and any torque guidance. |
| Foil liner | The aluminium layer heats, while the heat-seal layer bonds to the container material. | Liner construction, intended container material and supplier confirmation. |
| Product or substitute | Residue, heat sensitivity and leakage behaviour can affect acceptance checks. | Product type, safe handling notes and whether the sample is production product or substitute. |
Which formats should be included?
Include the boundary formats: the smallest cap, largest cap, tallest container, widest mouth and any pack expected to be unstable or difficult. A single easy sample can prove that induction sealing is possible, but it does not prove that the line can handle the full SKU range.
For a contract packer or multi-SKU site, group samples by cap diameter and liner type. If two products use the same cap size but a different liner construction, treat them as different trial conditions until proven otherwise.
What should be recorded during the trial?
- Cap, liner, container and product reference for each test.
- Sealing head used and approximate head height or working gap.
- Power setting, conveyor speed and bottle spacing used for accepted samples.
- Rejected settings that caused weak bonding, overheating or inconsistent results.
- Visual, peel and leak-check outcome after the agreed cooling interval.
- Operator notes on cap application, neck cleanliness and bottle stability.
How should pass/fail decisions be made?
Agree the pass/fail checks before the trial starts so the result is not judged only by appearance. For many packs, visual inspection should be combined with a peel check and an appropriate leak or handling check. The acceptance method depends on the product, container and buyer's quality process.
If a pack fails, keep the failed sample and record the setting that produced it. A controlled failure can be useful because it shows the edge of the sealing window and helps operators understand what to avoid during changeover.