A useful trial proves a repeatable process, not one attractive pack
A sleeve sealer sample trial should answer whether the proposed wrapper, seal system, shrink tunnel, cooling and discharge route can produce the required bundle under representative conditions. The test should use production-equivalent products or weight-matched samples, the intended tray or pad, and the proposed PE film specification. Empty lightweight containers can behave differently from filled products during collation, acceleration, tunnel heating and cooling.
Agree the test plan before samples are shipped. Identify every format that matters, especially the smallest, largest, lightest, heaviest and least stable packs. Define the intended bundle pattern, product orientation, upstream presentation, target production rate and downstream handling. Where one format is expected to represent a family, record why it is the worst case.
| Stage | What to define | What to record |
|---|---|---|
| Before the trial | Products, pack patterns, dimensions, weights, film, target rate, utilities, layout constraints and acceptance criteria. | Approved sample list, drawings or photographs, film data and test-plan revision. |
| Set-up | Guides, collation, film threading, seal position, tunnel settings, conveyor speed, pack spacing and cooling arrangement. | Recipe or setting sheet, machine configuration and roll identification. |
| Steady running | Representative duration and quantity at the agreed operating condition rather than a single cycle. | Achieved rate, interruptions, rejects, operator interventions and pack observations. |
| Stops and restarts | Starved infeed, blocked discharge, normal line stops, restart sequence and warm-up recovery. | Pack disposition, safe recovery method and time or product needed to return to the accepted condition. |
| Changeover | Required adjustments between agreed formats and verification of the first acceptable pack. | Change parts or settings, tools, access needs and first-off approval record. |
| Finished-pack checks | Collation, seal continuity, shrink uniformity, product condition, cooling and handling performance. | Photographs from agreed angles, retained samples and signed exceptions. |
Define acceptance in observable terms
A statement such as “good shrink” is not specific enough. Define which openings are acceptable, where the seal should sit, what level of wrinkle is permitted, whether artwork or labels may distort, how the pack must be lifted, and what transit or pallet-handling test is relevant. Separate cosmetic preferences from functional requirements so decisions can be made consistently.
For a factory acceptance test, also record guarding and control checks included in the agreed scope, documentation available at handover, alarm and stop behaviour, product-clearance arrangements and any open actions. Site acceptance should confirm the installed utilities, line interfaces, product supply and downstream handling that could not be reproduced at the factory.