Calibrating Inline Barcode Verifier Systems
High-speed inline barcode verification systems seem to be all the rage right now, and for good reason. Many of these systems integrate verification info other important compliance functions, and from a purchasing viewpoint, the additional function seems like a wise expenditure. We would agree but with some cautions and clarifications.
We are not intimately familiar with every integrated system available, but from what we have seen, there does not appear to be a single system that is ISO compliant. This is not an intrinsic deal-breaker, but it is important to know if you are investing in such a system. They are expense and sometimes over-promise.
On the plus side, an inline system can provide what we call print quality analysis (PQA) based on trending. Given a “golden” or benchmark barcode, a high-speed system compares subsequent barcodes and detects subtle variations that could eventually become failed scans. This is good to know. The reports can resemble the ISO template, although the verifier is not compliant. This can be misleading and cause a false sense of confidence.
To be compliant, verifier lighting must be in the ~660nm spectrum and eliminate any ambient light influence. Many of the systems we have seen operate in white light; none of them eliminates ambient light. Justification relies on “overcoming” ambient light with the strobes and sensors that flood the barcodes as they speed by beneath the scanner, but how has this been substantiated over what range of weeks and months? Seasonal changes, proximate windows, updates to ambient lighting and myriad other factors are dismissed out-of-hand.
That benchmark barcode can make some assurances that the system is operating nominally over time. However, without at least an initial calibration of the system, even the “golden” barcode can be suspect. What if the golden barcode is not as represented or believed? The bottom line is this: if the customer claims the barcodes are not performing, what is the basis for your defense?
From a quality standpoint, there are two issues here. The first is initial installation. Even a technically non-compliant system can only be authoritative if it is calibrated—against what: at very least a Calibrated Conformance Standard Test Card such as a GS1 or Applied Image test target, but these only provide a Pass or Fail without any further insight.
An ISO compliant off-line verifier is essential for calibrating a high-speed system. Detecting minute changes in parameters over time is meaningless if those parameters were not reported correctly at the start. Because it grades each ISO parameter separately, the off line verifier will point to the adjustments that are necessary for bringing the high-speed system into specification.
The second issue is system performance over time. Best practices would be reconfirmation on a regular basis. Most ISO auditors require test equipment to be re-certified annually. How many bad barcodes could escape and damage an important relationship if the verifier is re-certified annually? Quarterly or even monthly checking does not seem too often—especially since the whole process takes about 2 minutes.