Fill level, cap and seal inspection for production lines
Under-fill, missing or tilted caps, broken tamper bands and visible seal faults on bottles, jars, cups and tubs.
Technical review: Frank GuoReviewed
A camera station can detect under- and over-filled containers, missing, tilted or high caps, broken tamper bands and visible seal faults such as a missing foil or a creased heat seal. Fill level works on clear or translucent containers with a backlight; opaque containers limit what a camera can see. A visual seal check does not prove a pack is leak-tight. We confirm what your containers allow on real samples first.
What a fill, cap and seal station checks
Four checks, often combined in one station. Which you need, and the limits, are set at the sample test.
Fill level
Finds the liquid line against a backlight and compares it with a minimum and maximum taught from good containers.
Cap presence, tilt and height
Missing caps, cocked caps and caps that sit high because they were not screwed down.
Tamper band
Broken, missing or ridden-up tamper-evident bands.
Visible seal
Foil present, heat seal on cups and trays visibly complete, creases or product in the seal area.
Fill level by container type
| Container | Camera fill check | What to watch |
|---|---|---|
| Clear glass or PET | Usually feasible with a backlight. | Foam, bubbles, condensation and liquid still moving at the camera. |
| Translucent plastic | Often feasible where the liquid line shows through. | Wall thickness and colour vary; confirmed on your samples. |
| Opaque, tinted or fully sleeved | Not feasible: a camera cannot see the liquid. | Fill needs another method, such as weighing; caps and seals can still be checked. |
| Cans and cartons | Not feasible for fill level. | Cap, lid and code checks remain possible. |
Where fill, cap and seal inspection stops
We agree these boundaries before a project starts, so nobody expects the camera to do what it cannot.
Not detectable with a camera
- Leak-tightness. A seal that looks complete can still leak. Proving it is sealed needs a leak test.
- Fill in opaque containers. The liquid line cannot be seen through opaque walls, full sleeves or cans.
- Cap torque. A cap can sit straight and still be under-tightened; torque is checked another way.
Works reliably when
- The container shows the liquid. Clear or translucent walls, with a backlight behind them.
- The liquid has settled. The camera sits where foam and sloshing have calmed, with stable spacing.
- Limits come from your specification. Fill and cap limits are taught from agreed good and bad samples.
How a fill and cap station is laid out
Plan view of a typical station. The real layout follows the site survey.
Swipe sideways to see the whole drawing →
What a pass and a reject look like
Illustrations, not images from a real line. The fill limits and how much cap tilt is acceptable come from your specification and are set at the sample test.
Fill and cap correct
Liquid line between the limits, cap present and seated straight.
Fill below minimum
The liquid line is below the minimum taught from good bottles. The bottle is tracked to the reject.
Cap tilted and high
Fill is correct, but the cap outline is tilted and sits above the seated position.
What we need to know about your line
These conditions decide the station design. Each is confirmed on site or during the sample test.
| Condition | What we need to know | Why it matters | Confirmed during |
|---|---|---|---|
| Container and cap range | Container materials, colours and shapes, and cap types for every SKU. | Decides whether fill can be seen and how many views caps and bands need. | Sample test |
| Product behaviour | Foaming, sloshing, hot fill or condensation. | A moving or foamy liquid line needs the camera placed where the surface has settled. | Site survey |
| Line speed and spacing | Containers per minute and the gap between them. | Sets exposure and trigger; each container must be rejected on its own. | Site survey |
| PLC and reject | PLC make and model, spare I/O, existing reject. | Full containers need a reject that removes them without toppling the line. | Design review |
| Environment | Splash, washdown and cleaning routine at the mounting point. | Decides enclosure and mounting of camera and lights. | Site survey |
How the station is accepted
False rejects and missed defects pull against each other. We define both, and how they are measured, before FAT and SAT.
False reject rate
The share of good containers rejected, measured on agreed good samples at line speed, including normal foam. The acceptable level is agreed per project.
Missed defect rate
The share of faulty containers that pass, measured with seeded under-fills, loose caps and broken bands. The target is set with you.
Written scope
A signed list of what the station checks and what it does not, such as seal appearance but not leak-tightness.
What to prepare for the sample test
We check your filled and capped containers before proposing a station. We confirm quantities and shipping with you first.
Sample preparation guideGood samples
Filled, capped and sealed containers for each SKU, covering normal variation.
Defective samples
Under- and over-fills, tilted or high caps, broken bands and bad seals, clearly marked.
Specifications
Container and cap drawings, and the fill limits you work to today.
Line information
Line speed, spacing, PLC make and model, and the reject you have or need.
Fill, cap and seal questions
Can a camera detect underfilled bottles?
How are missing or tilted bottle caps detected?
Can visual seal inspection prove a package is leak-tight?
What about foam and sloshing?
Request an assessment for this application
Tell us about your containers, caps and line, and send good and bad samples. We will tell you what a station can check and where the limits are.