Seal seam inspection using thermal imaging on thermoformed packaging

In the food industry, heat sealing is used to weld the lidding film onto the rim of thermoformed trays under heat, contact pressure, and a defined sealing time. Fluctuating process parameters or contamination in the sealing area — such as trapped product residue or fine threads — can lead to leaking seams.
Since the seal cools within seconds of the welding process, reliable inspection must take place immediately after sealing to detect leaks before defective packages reach retail unnoticed.

Directly after the sealing station, and therefore while the seam is still warm, a thermal imaging camera captures the temperature distribution along the entire seal contour. Three criteria are evaluated: a constant seal width along the entire seam, a constant temperature range within fixed tolerances, and an uninterrupted, closed contour. Deviations, for example due to product inclusions or fine thread interruptions, appear as characteristic temperature jumps in the thermal image and are reliably detected. When a leak is detected, an NIO signal is issued and the package is removed from the process.

Immediate thermographic inspection during the sealing process detects leaks that would no longer be visible once the seam has cooled. This means leaking packages that would otherwise reach retail undetected are identified, avoiding the associated complaint and recall risks.
Manual visual inspection is eliminated, and integration takes place without any changes to the existing sealing and labeling line.