Zero print defects without slowing the line

At real lithography line speed, the human eye tires and lets through sheets with color registration defects, scratches or varnish bubbles. iLEAN Edge places an overhead camera that inspects every sheet in milliseconds.

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Overhead camera inspecting printed sheets as they leave the printing unit, with an ejection system diverting a sheet with a color registration defect before varnishing
The problem

At line speed the eye tires, and sampling leaves gaps.

Those defective sheets move on to forming and end up as a defective can body or, worse, a varnish failure that compromises food contact. Sampling inspection leaves gaps.

  • At real lithography line speed, the human eye tires and lets through sheets with color registration defects, scratches or varnish bubbles.
  • Sampling inspection of 1-2% of sheets leaves every other sheet unchecked. A register shift that starts between two samples can run for hundreds of sheets before anyone sees it.
  • A defective sheet moves on to forming and becomes a defective can body or, worse, a varnish failure that compromises food contact. Forming, welding and coding add cost to a sheet that was already lost.
  • By the time the complaint arrives from the packer client, the run has been formed, coded and shipped. At that point the cost is no longer a sheet, it is a run and a client conversation. And the root cause is hard to find, because nobody knows which sheets of the run were affected.
How it fits the IRIS system

Edge — local CNN vision over the litho line, no image sent to the cloud.

Edge — local CNN vision, with no image sent to the cloud (latency, cost, bandwidth). Model trained on good and bad examples of the specific format and Pantone. Automatic rejection before forming.

The model is trained on good and bad sheets of your own formats and Pantones, not on a generic library. That is what lets it reject a register shift without rejecting the design. And it sees every sheet, not the one in fifty that a person has time to look at.

See the full IRIS architecture →

Before and after

Sampling the litho output versus inspecting every sheet

AspectSampling inspectionWith iLEAN Edge
Sheets inspected1-2% sample100%
Color registration defectCaught if it falls in the sampleRejected sheet by sheet, at line speed
Varnish bubbles and scratchesDepend on the inspector's fatigueClassified at line speed
Where a bad sheet is stoppedAt the packer client, as a complaintBefore forming
Image processing—Local, no cloud latency or bandwidth
Model reference—Your formats and Pantones

1-2% sampling → 100% sheet control. Print/varnish defect complaints → drastic reduction.

Impact estimate

Impact estimate — to be validated with your numbers.

The block below is an estimate to be validated against your plant's actual data. We put it forward so the committee has an order of magnitude; we refine it during the assessment.

  • Estimated payback 5-12 months, depending on the current reject ratio.
  • Inspection coverage goes from a 1-2% sample to every printed sheet. Every reject is stored with its image, which turns complaints into data per unit and per run. Quality can see whether a defect grows with a blanket, an ink batch or a specific unit of the press.
  • Print and varnish defect complaints from packer clients drop sharply. Each one avoided is a client conversation that does not have to happen.
  • And defective sheets are removed before forming adds the cost of the can body to them.

Estimated payback of 5 to 12 months depending on current reject ratio. Estimate to validate.

And the fair question from the production manager

“What if it rejects good sheets?” — the false reject is the real risk, which is why the model is trained on good and bad examples of the specific format and Pantone, under that line's lighting. Classifying a known defect type on a known design is an anchored task where the best models drop below 1.5% error [1], and borderline sheets are escalated to a person instead of being discarded. Every decision on a borderline sheet feeds back into training, so false rejects fall as the model learns your designs.

[1] OpenAI paper "Why Language Models Hallucinate", 2025 — on the reliability of AI in anchored tasks.

Frequently asked questions

What people ask about inspecting printed sheets

Does it slow the litho line down?

No. Inference runs locally next to the line in milliseconds per sheet, without sending images to the cloud. It does not depend on the plant network either, so a network outage does not leave the line uninspected.

Which defects does it detect in metal packaging?

Color registration shifts, scratches and varnish bubbles, the ones that become a defective can body or a food-contact varnish failure if they pass. The defect catalog is agreed with quality at commissioning, using real sheets from your runs.

What happens with a new design or Pantone?

The model is updated with examples of that format. A high-mix litho plant usually switches the model according to the active run. New formats are added from a short series of good and bad sheets, not from a new project.

Where does a rejected sheet go?

To an ejection point before forming, while good sheets keep flowing to varnishing; nothing has to stop. Each rejected sheet is stored with its image and run, so quality can see which defect is growing and on which unit.

Does it replace the quality inspector?

No. It takes over the tiring sheet-by-sheet check and leaves the inspector the borderline cases and the root cause analysis. The inspector stops being the inspection and becomes the person who decides on what the camera doubts.

Let's talk

Tell us what share of your litho output you can inspect today.

We work on your plant's real data, not ours. Assessment with no commitment.

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