Vision systems are on the rise (at least from a marketing perspective) in material handling for manufacturing and supply chains, and they are a logical place for a variety of inspection operations, barcode verification being one of the most recent. Machine vision has advanced in recent years and can perform many important functions, including:
- Presence/absence checking for date codes and lot numbers
- Parts inspection
- Dimensional and volumetric measurement
- Cap and label presence and placement
- Correct label confirm
- Fill level confirm
…and a growing list of other functions.
Some vision systems perform highly accurate measurements, at the micron level, and at very high speeds. Because of this, vision systems claim to be superior to so-called “traditional” verification, and avoid using the terminology, referring to their barcode quality checking as “qualification.”
Promoters of vision systems tout the savings of an automated system over a manual off-line verifier: savings of time and money. It is claimed that inline inspection means less downtime—that is of course if no problem barcodes are found. If a vision system finds a poor quality barcode every 5 minutes, the downtime savings quickly disappear. The initial cost of a vision system is not mentioned.
Qualification systems claim to be superior to off line verification because they track trending. This is not a differentiator: off line systems also track trending, but not of 100% of the barcodes as a qualification system does.
A 100% inspection system neither creates nor improves quality. Qualification does not ensure better barcodes than verification. Identifying and controlling the variables in the print process does. Burned out thermal print head pixels and clogged ink jet nozzles can largely be avoided with quality-focused preventive maintenance.
Barcode quality systems should focus on what is most effective. Barcodes that grade an ANSI A are not a worthwhile goal of any quality program. Predictable and repeatable C grades are much more sensible. It is wiser to invest resources to achieve these goals. One hundred percent verification—or qualification—is overkill from both a cost and a results standpoint.
Get full value for what you pay. Identify the variables in your barcode print process. If you vend out barcode printing, make it clear to your vendor that they are responsible for barcode quality. Insist on periodic (at least) verification reports in the execution of their contract. Verification reports with each order would not be excessive.
Barcode verification (or qualification) in a vision system? Just because you can doesn’t mean you should.
Comments are always welcome.
