Suitability depends on the complete product and exposure window
A heat-sensitive product may be suitable for sleeve wrapping when the required PE film shrink can be achieved without unacceptable change to the contents, container, closure, label, adhesive, tray or finished bundle.
The answer cannot be established from a generic tunnel temperature. Dwell, airflow, product mass, pack spacing, starting condition, film, cooling and the point of measurement all affect exposure. Use representative production samples and define what must remain unchanged.
Check every component that experiences the process
| Component | Possible concern | Evidence required |
|---|---|---|
| Product contents | Temperature-related quality, pressure or condition change. | Application-specific acceptance defined by the responsible product owner. |
| Container and closure | Softening, distortion, leakage, panel movement or seal change. | Inspection before and after the complete cooled process. |
| Labels, print and adhesive | Lifting, bubbling, discolouration, migration or loss of position. | Approved appearance and adhesion after cooling and handling. |
| Tray or pad | Warping, moisture response, adhesive change or loss of support. | Bundle stability through accumulation and lifting. |
| PE film and seal | Required shrink and seal strength within the acceptable exposure window. | Repeatable pack quality at representative tunnel loading. |
Build the trial around the finished-product risk
- Define the product and packaging properties that must not change.
- Use production-representative samples and starting conditions.
- Establish a controlled tunnel window with one variable changed at a time.
- Inspect the pack after cooling, accumulation and intended handling.
- Obtain approval from the people responsible for product and packaging quality.
Consider another route when the window is too narrow
If the PE film cannot shrink and seal within conditions that protect the product, another secondary-pack design, support method or wrapping technology may be more suitable. The decision should not rely on increasing line speed or reducing heat without proving the resulting seal and bundle.
- Do not use empty containers as the only heat-sensitivity sample.
- Include labels, closures and current primary-pack seals.
- Test production loading, not only isolated packs.
- Record the cooled product condition and any delayed change.