Judge the complete cooled bundle
The final decision should not be based only on how a pack looks at the tunnel exit. A sleeve-wrapped bundle must remain acceptable after the film has cooled, the pack has crossed discharge transfers, and it has been accumulated, lifted and handled in the intended way. Define the acceptance point and the handling sequence before testing.
Separate functional requirements from presentation preferences. Functional requirements may include keeping the group together, protecting the tray, allowing mechanical handling and preventing product loss. Presentation requirements may cover seal position, wrinkle, side opening, printed-film registration or visibility of labels. Both can matter, but each needs an agreed limit and inspection method.
| Category | Acceptance questions | Evidence method |
|---|---|---|
| Collation | Are rows square, products upright and the tray or pad correctly positioned without trapped edges? | Overhead and side photographs before wrapping and after cooling. |
| Seal | Is the seal continuous, correctly located and free from open areas, contamination or damage that reduces pack integrity? | Full-length inspection under consistent lighting; retain a representative sample. |
| Shrink finish | Is film recovery sufficiently uniform for the pack, without unacceptable loose areas, holes, burn-through or concentrated wrinkles? | Front, rear and both side views after the agreed cooling time. |
| Product condition | Are containers, closures, labels, trays and printed surfaces undamaged and within the agreed appearance standard? | Compare with an unprocessed control sample and inspect heat-sensitive areas. |
| Cooling | Has the film stabilised before accumulation or lifting, and does the pack retain its form after downstream contact? | Observe discharge, accumulation and first handling point. |
| Handling integrity | Can the bundle be transferred, lifted, placed and stacked in the intended manner without opening or losing product? | Repeat the actual manual or mechanical handling sequence using production-weight packs. |
Create defect classes that operators can apply
Use clear examples for acceptable, rework and reject conditions. Avoid broad instructions such as “make the pack tighter” because operators may compensate with excessive heat. A visual standard should identify the pack format, film, approved settings, inspection point and defect class. Where the same appearance has different consequences on different products, create format-specific examples.
Sampling frequency should reflect the process and the site's quality system. First-off packs after warm-up, film change, product change, maintenance or a prolonged stop deserve specific attention. If the acceptance standard changes, repeat the relevant trial and update the controlled record rather than relying on verbal instructions.