Visible seal inspection

Vision seal inspection for visible packaging defects

Inspect visible heat-seal and closure regions for contamination, folds, gaps, wrinkles and incomplete presentation. The system is designed around the sealing process, material behaviour and defect size that your quality plan requires.

Discuss this application Call 01865 416657

Inspection overview

Make the seal region measurable and repeatable

Seal inspection performance depends on the pack being flat, stable and consistently illuminated. Transparent film, printed webs, food residue and natural seal texture can all influence the boundary between an acceptable and failed pack.

Vision is strongest for visible surface conditions. It can complement—but does not automatically replace—destructive seal checks, pressure decay, vacuum, gas or other integrity testing needed to find hidden channels and microscopic leaks.

Visible surfaceInspection scope

Seal regionTargeted imaging

Leak test readyCombined systems

Checks that can be combined

The final inspection set is selected from the visible features, risk, product presentation and achievable image resolution.

Visible product in the seal region
Incomplete or missing visible seal pattern
Folds, creases and trapped film
Seal width, position and continuity
Open pack or lifted-lid condition
Tray-rim and pouch-edge presentation
Lidding-film or top-seal alignment
Correlation of seal defect to reject action

Application details we review

Early clarity on these points helps avoid false rejects, blind spots and mechanical changes late in the project.

Seal material and printed film
Transparent or opaque product
Natural seal texture and wrinkle range
Smallest actionable visible defect
Pack flattening and conveyor stability
Relationship to offline integrity tests

Define what vision can see—and what needs another test

We classify visible defects with real samples and identify any integrity risks that require a complementary leak-testing method.

Feasibility work establishes the camera view, lens, light, exposure and image-processing approach. We then define the enclosure, conveyor changes, controls, operator interface and rejection needed for production.

Explore by industry

Food, beverage, pharmaceutical, cosmetics, chemical and household, and contract packing applications.

How we deliver

From feasibility to supported production

Inspection performance depends on the complete cell, so optics, mechanics, controls and rejection are developed as one project.

Define

Products, defects, speeds, environment and acceptance criteria.

Prove

Sample imaging, lighting trials and achievable defect limits.

Integrate

Mechanical design, guarding, PLC, recipes and reject tracking.

Support

Commissioning, operator training and production handover.

Seal inspection questions

Technical questions, answered clearly

Is vision seal inspection the same as leak testing?

No. Vision checks observable seal appearance. A pack can look acceptable yet contain a microscopic or internal leak, so critical integrity claims may require a separate validated leak test.

Can food trapped in a tray seal be detected?

Visible product crossing the seal region may be detected where the lighting, colour contrast and tray presentation reveal it consistently.

Can transparent film seals be inspected?

Yes, although reflections and the product background can make the application challenging. Diffuse lighting, polarisation and trials with real film are important.

Can the inspection run immediately after sealing?

Often, but heat, steam, motion and film relaxation can affect imaging. The inspection position is chosen after reviewing the process and available settling distance.

How small a seal defect can be found?

That depends on field of view, camera resolution, contrast, line stability and processing time. A sample trial establishes a defensible minimum detectable defect.

Start with the product and defect

Define a practical inspection concept

Send us the pack formats, line speed, available space and the defects you need to catch. Samples and images are especially useful.

Discuss your application

Call Oxford Vision Systems01865 416657Email our sales teamsales@oxfordvisionsystems.co.uk

Build a seal-defect library that reflects real production

Label each example by the actual decision

Use the quality team’s accepted and rejected packs, including examples close to the boundary. Identify whether the concern is trapped product, a fold, seal position, visible discontinuity or another observable condition. Retain normal texture and wrinkle examples so the system is not tuned to reject harmless variation. Separate appearance decisions from integrity-test results in the record. A pack can have an unattractive seal that meets its relevant requirement, or a visually acceptable region with an integrity issue that the camera cannot establish.

Challenge film, pack and viewing conditions

Trial the approved material range, print variants and product backgrounds in the proposed position after sealing. Record heat, steam, reflections, pack movement and time allowed for film to settle. Review corners and transitions as well as the central flat area. If a portion of the seal cannot be seen repeatably, document it as a coverage gap and investigate another view or method. More image processing cannot recover a feature hidden behind an opaque material or outside the camera’s view.

Connect the finding to the quality plan

Agree how vision results are compared with the pack owner’s selected integrity tests and what evidence is needed to investigate disagreement. Do not assume that passing one method guarantees passing the other. For production integration, identify every uninspected or uncertain pack and test the agreed reject tracking and containment response. Retain trial references, material identities and relevant images so later film or product changes can be reviewed against the original conditions. Any minimum detectable defect or performance claim should come from this demonstrated scope.

Manufacturer product photographs: Zebra machine vision camera from the VS70 product family. Equipment examples; application-specific optics, controls and suitability are assessed separately.