Thermal imaging vs visible machine vision
The two methods measure different information. They can be alternatives or complementary views, depending on the required decision.
| Method | Measures | Often useful for | Key limitation |
|---|---|---|---|
| Visible vision | Shape, colour, contrast, position and surface appearance | Film presence, alignment, folds, visible contamination, seal geometry and closure features | Cannot see a condition that creates no usable optical difference |
| Thermal imaging | Infrared surface-temperature pattern | Recent heat-seal patterns and defined process anomalies with repeatable thermal contrast | Contrast changes with time, materials and process conditions |
| Combined views | Visible appearance plus thermal pattern | Applications where the two signals separate different defect classes | Adds cost and complexity; only justified when trials show value |
Typical thermal seal-inspection applications
Potential applications include tray lidding, pouches and sachets, heat-sealed containers and induction-seal processes. A thermal view may help where a defined sealing condition changes heat transfer, but the camera does not infer pack integrity from heat alone.
- Compare the continuity and distribution of a recent heat pattern
- Locate specified cold or hot regions relative to an agreed reference
- Classify repeatable anomalies linked to known sample defects
- Combine thermal results with visible checks and product tracking
- Send failed-pack results to a verified reject sequence
For broader heat-seal applications, see heat-seal inspection systems. For food trays and flexible packs, see the food packaging guide.
What thermal inspection does not prove by itself
A useful thermal anomaly is not automatically the same as a leak measurement or seal-strength result.
Thermal inspection evaluates the surface temperature pattern that is available at the inspection point. A very small leak, internal channel or weak bond may not create a reliable thermal signature. Conversely, acceptable material or temperature variation may alter the image without representing a faulty pack.
Feasibility must be established using the customer’s packs, known failures and production variation. Where the specification is leak rate, pressure retention, gas composition or mechanical seal strength, use a suitable integrity or destructive test method. See the method-selection guide.
Engineering factors that control repeatability
Prove the useful thermal signal before final engineering
Send representative good packs, known defects and normal production extremes. Include time from sealing, line speed, pack spacing, film construction, format range and the precise acceptance requirement. Trials should show that the chosen features remain separated across realistic variation—not only one ideal sample.
Request a thermal feasibility review