Originally posted June 11, 2014
Is the Graphics Revision Number accurately being verified on your packaging materials?
16 recalls in the span of 7 weeks were related to undeclared allergens – allergens that were missing from the ingredients list because the wrong and outdated revision of the packaging graphics were being used.
To prevent potential recalls, machine vision is used to monitor the Graphics Revision Number present on packaging materials.
Machine Vision-Based Package Verification
Machine Vision in package verification has eliminated numerous potential recalls caused by using the wrong carton, label, pre-printed container, or web material when packaging a food product. This is especially critical, when the food contains one of the eight key allergens (soy, milk, eggs, peanuts, tree nuts, fish, shellfish, and wheat).
Taking Package Verification a Step Further
Recently, Machine Vision Company LLC (MVC) has been asked to take this one step further by not only verifying that the correct packaging is used, but to verify that the expected revision of the packaging materials is being used. For example, the UPC code for a product may not change despite changes made to the ingredients list.
This can impact marketing, as well as food safety, when the incorrect revision of the carton, label, or web graphics is used, especially if milk, eggs, nuts, wheat, or other allergens are ingredients that are not correctly represented on the ingredient list.
Shortcomings of Current Graphics Revision Number Verification
A human readable graphics revision number is often placed near the UPC code or elsewhere on the packaging so that the operator can verify the revision number of the packaging materials and then load the correct materials.
However, the alphanumeric representation of the graphics revision number can be problematic in that:
- An operator may still load the incorrect packaging materials after initially verifying the graphics revision code
- The graphics revision code may not be in a location that can be monitored during production
- A match-pattern cannot be used to verify the expected graphics revision code because one or two incorrect characters will minimally affect the match-score
- The reliability of OCR/OCV (optical character reading/optical character verification) is dependent upon character positioning, font used, absence of confusing-looking characters (look at the “5” and the “S” in the example on the right), and other factors.
Thus, MVC recommends the use of a 2D Matrix Code for Graphics Revision Number Verification.
MVC Recommends Using a 2D Matrix Code
The 2D Data Matrix code is ideal for machine vision-based verification of a packaging’s Graphics Revision Number. It is robust, tolerant of minor damage when ECC200 error correction is used in the code, and will never produce the wrong answer; the worst case is the code is not readable and the product is rejected. The 2D Data Matrix can be sized down to ¼ inch, depending on the content.
2D Matrix Code Location is Key
For production, it is important to select the proper location where this code is printed on the packaging material. The 2D code must be consistently visible such that it can be easily read while the production line is running. Examples of 2D Data Matrix code positioning include:
- Flat Label – 2D codes presented on a flat label can be printed anywhere that is included in the camera’s field-of-view, especially if other identifiers are also being inspected.
- Cartons – 2D codes printed on a carton should be on a panel that is visible to a camera, such as the top-facing or panel that faces the side of the conveyor. The 2D code may also be printed on a flap which, at the time of inspection, will be visible.
- The 2D code should not be positioned on the leading or trailing edge of the carton while it is moving along the conveyor.
- Round Containers – For randomly-oriented round containers, the 2D code may be placed in any position on the circumference of the container if 360 degree inspection is being used.
- The 2D code may be in any position in which it will be visible to a camera.
- Lids – The 2D code may be in any position on a lid.
- Web – As with labels, the key requirement is that the 2D code is visible to a camera.
To discuss your requirements for adding Graphics Revision Number Verification on your production line, contact Joe Gugliotti at Machine Vision Company, 978-551-4160 or firstname.lastname@example.org, or visit Machine Vision Company’s web site at www.machinevc.com.