How the code is printed
Inkjet dots, thermal transfer and laser marks each look different to a camera. Dot codes need fonts and spacing the reader expects. Laser marks on film often need low-angle light.
Guides
Date and lot code verification on packaging lines
A missing or wrong date code can turn a full run into a hold. Inline verification checks every pack, not a sample, and stops the problem at the printer.
What does verification check?
Three things: that a code is there, that it can be read, and that it says what it should say for the order on the line. Reading a code is not the same as checking it. The station compares what it reads with the expected date, lot and expiry from the recipe, the work order or the plant's MES.
What decides how well it works?
The surface under the code
Codes on foil, shrink film, curved bottles and dark cartons need different lighting. Glare on film is the most common reason a good code reads as bad.
Reading versus matching
Character recognition reads the text. Character verification compares it to a known string and grades how well each character printed. Many lines need both: read the code and confirm it matches.
Where the expected value comes from
Typing the code into the station at changeover invites mistakes. Pulling it from the printer, the recipe or the MES removes a step where people can slip.
What happens on a fail
A failed pack should be rejected and confirmed in the bin, and repeated fails should stop the line so the printer gets fixed.
Records
Saving the image and result for each fail, and counts for each lot, gives quality a record when a question comes up later.
Bring printed samples from the real printer, including bad ones: smudged, faded, missing and wrong. They show what the station has to catch.
FAQ
Common questions
QCan it read codes on curved bottles?
Yes, with the camera placed for the curve or with more than one camera. Very tight curves may need the bottle turned or a line-scan setup.
QDoes the font matter?
Yes. Clean, evenly spaced fonts read most reliably. Small changes to the printer settings often help more than software.
QCan it check the code at line speed?
Yes. The camera is triggered for each pack, and the check runs in milliseconds.
QWhat if the printer and the station disagree on the date?
The pack fails. That is the point: the station catches the wrong setting before a full run is printed.