Before a can gets its label, the short variety code on its end is the only thing that says what is inside. A vision system reads that code on every can with a GigE Vision camera, a dome light and deep learning OCR, compares it with the product the line is supposed to be running, and rejects any can that doesn't match. The read works in any orientation, so it doesn't matter how the can turns on the conveyor.
What is a variety code on a bright-stack can?
Many canneries fill, seal and process cans first, then store them unlabeled. Those plain cans are called bright stock, or bright stack. Labels go on later, when an order comes in. It lets one production run serve several labels and customers.
The catch is that a bright can looks like every other bright can. What tells them apart is a short code marked on the can end. On the line in this article, it is a three-letter variety code that identifies the contents. The code is inkjet-printed, so the reader has to cope with the smears, faded ink and missing dots that inkjet codes pick up on a fast line.
When the cans come back out of storage to be labeled, that code is the only link between what is inside and the label that is about to go on.
Why does a misread variety code matter?
A can labeled as the wrong variety is mislabeled product. If the contents include an allergen the label doesn't declare, it becomes a recall. FDA has reported that undeclared allergens were the leading cause of Class I food recalls for at least three years running[1]. Class I is FDA's most serious recall class[2].
A person checking codes by eye at line speed will miss some. A camera reading every can, every time, keeps the wrong cans from reaching the labeler.
What does the system use?
- A GigE Vision camera. GigE Vision is the industrial Ethernet camera interface standard maintained by A3[3]. It is not a brand. Cameras built to it stream images over standard Ethernet cable, so the camera can sit at the conveyor while the vision computer sits in a panel.
- A dome light. A can end is bright, curved and reflective. Direct light turns it into hot spots and dark patches. A dome surrounds the end with even, diffuse light, so the code reads the same whether it sits on a flat panel or near the curve.
- Deep learning OCR to read the code. It outperforms rule-based methods on degraded or low-contrast codes and requires no per-code training.
- An encoder-tracked pneumatic reject, driven by a PLC output, that removes the exact can that failed.
How does the read work in any orientation?
Cans spin and shift on a conveyor, so the code can land at any angle. The system first finds the code on the end, then lines up the reading window with it before reading. Because the read is fixtured to the code this way, it reads in any orientation[4].
A typical strobed exposure here is about 60 microseconds, which freezes the code well enough to read at speed[5]. Lines like this one run from 300 to 1,200 cans per minute; 1,200 cans per minute is the ceiling for code-reading tasks like this one.
How does the line know which code to expect?
From the plant's own system. When a new order starts, the MES or production system sends the expected variety to the vision system over EtherNet/IP[6] or TCP/IP. The changeover happens live, with no one typing a code into a camera.
From then on, each can either matches the running variety or it doesn't. A can that doesn't match, or a code that can't be read, goes to the reject. Each result is logged with a timestamp, so the plant can trace which cans ran when.
What does the operator see?
The same JM Automated Solutions HMI used on our other systems: the live image, the code as read, pass/fail, false-reject counts and the current recipe. The system is calibrated against known-good cans at setup and re-checked at changeover. The hardware is built for washdown areas.
What checks pair well with it?
The variety code check confirms what is inside the can. Its companion is label verification at the labeler exit, which confirms the label that went on matches the order. Run together, they close the loop: the right product, with the right label, on every can.
Want to know if your variety codes will read?
Send us a handful of cans, including a few with faint or smudged codes. We'll tell you in writing whether a camera can read them reliably on your line, before any proposal or price. Book a call or send JM Automated Solutions a message.