Cameras
Five views of the seam
Four side cameras spaced around the can see the full 360° of the seam. One top camera looks down on the end to check that the seam is circular.
Station
Can seam inspection station.
Cameras image every can as it leaves the seamer and measure the visible seam against the can maker’s spec. A can outside the window is rejected, and a run of rejects tells maintenance to check the seamer itself.
Tell us about the system Read the article
Full write-up: How vision inspection catches double seam defects on a canning line
How it checks
How does the station check every seam?
The measurement happens on the line, on every can, between the plant’s scheduled seam checks.
Lighting
Dark-field light
Light comes in at a low angle, so flat surfaces stay dark and the top and bottom edges of the seam light up. Sharp edges are what a repeatable measurement needs.
Measurement
Seam height against spec
Seam height is measured in thousandths of an inch around the whole seam and compared with the can maker’s limits. Too short fails. Too tall fails.
Reject
Encoder-tracked air reject
A failed can goes to an encoder-tracked pneumatic reject driven by a PLC output. Its image, measurement, reason and timestamp are saved.
Reject logic
What does a run of rejects tell maintenance?
One bad can and a string of bad cans mean different things, so the station treats them differently.
One reject
One bad can
A single can outside the window is a bad can. The reject takes it off the line and the run continues.
Consecutive rejects
The seamer itself is failing
Several rejects in a row point to the seamer, not the can: for example, a worn second-operation roller or chuck. When the station sees consecutive rejects, it alerts maintenance to check the rollers and chuck.
Why sooner matters
Stop making bad cans
A failing seamer keeps making bad cans until someone stops it. Catching the run sooner means the crew can fix the cause sooner, instead of finding it at the next scheduled teardown.
Where it fits
What does seam vision not replace?
Teardowns
Internal dimensions still need a teardown
A camera cannot see inside the seam. Body hook, cover hook, overlap and tightness are measured by teardown, by a qualified person, on the schedule in the plant’s closure program. Seam vision supports, and does not replace, those teardowns.
Calibration
Calibrated against a teardown
The station is set up against a reference can whose seam was measured by teardown, and re-checked against the same can at changeover. If the camera and the teardown disagree, the teardown wins.
Risk
Why the seam matters
A seam that doesn’t seal can let contaminants in after processing, including the organisms that cause botulism. The inspection helps catch those cans. A joint GMA, FMI and GS1 US survey (2010) put the average direct cost of a food recall at about $10 million.
Next step
Start with your line.
Tell us what you make and what is getting through. Start with a feasibility study.
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