Bar Code Precise Quality Control
Verification should be part of daily life for those printing bar
codes. And yet, though most of us would
agree on the importance of checking bar codes, it's difficult to get a consensus
on how that should be done.
There are even differences of opinion on what verification is. To some, verification
is the process in which
trading partners agree that a certain bar code number matches a certain product
description. It is impossible
to determine if barcode symbols are good or in-spec. by looking at them and
it is impractical.
Companies that print large volumes of bar code symbols will buy
a fixed mounted bar code scanner to scan
bar code labels on an assembly (printer)
line so they can here the "beep" which represents a good read,
which supposedly verifies a good bar code symbol when the
scanner reads or beeps. The beep displays
visually or audibly a "good read", but the assumption
should not be a high quality printed guaranteed bar
code symbol because you may here later that the bar code symbols
would not work and the original printer
comes back with "The bar codes worked when they printed them!" This
method of verification with a bar
code scanner obviously does not ensure that the bar codes scan
at the other end of the supply chain where
your trading partner expects to scan and get a good first read rate (FRR)
first time every time.
A more accurate method of verification is to use a hand held bar
code verifier, which is designed to inspect
the bar code symbol or image. A bar code verifier can read a bar code symbol
and “beep” and send an
ASCII string of data to another peripheral or computer like a bar code reader
does. But a bar code verifier
measures the print contrast signal, dimensional tolerances, and wide to narrow
ratios of the bar codes image.
This traditional verification method is for
spot-checking only. Verifying each and every label is also impractical.
AIM (Automatic Identification Manufacturers), the UCC (Uniform
Code Council), and ANSI (American
National Standards Institute) developed a specification; ANSI X3.182-1990 Bar
Code Print Quality
document that discusses how the bar code scanners really "see" bar
code cards, labels or image. The ANSI
document is used in conjunction with other bar code specific documents
to define inspection criteria and is still
somewhat complicated. The newer hand held verifiers have specification criteria
built into them to make it easier
for the user to "grade" their bar code labels A-D for pass
and F for fail and can figure out the quality
interpretation learning curve in several days. They think they are in paradise
with their internal bar code
quality standards of excellence.
As more companies adhere to American quality standards like IS09000
and other quality initiatives, this paradise
becomes a weakening argument for verifying bar codes. Because IS09000 requires inspection instrumentation
to be calibrated to a known national standard on a scheduled basis. Some
verifier manufacturers may not have
a comprehensive calibration plan (back at the factory) for their hand held products,
not to mention bar code
material, bar code printer and bar code scanner calibration. Every company
that wants to include bar code
inspection in its ISO quality system requires calibration. Without adequate
calibration, it's not uncommon for two
brand new verifiers to disagree. One manufacturer verifier may accept a bar
code image, and the second may
reject it as nonconforming. Even with these brand new off the shelf tools, verification
has been confusing to ADC
Manufacturers, card and label printers, VAR's and System Integrators not to
mention the end-user community.
Commercial printers and the packaging industry can have actual
100% inspection with a in-line and on-line
bar code verifiers for high speed ANSI bar code measurement and inspection.
Some are laser based and
some are vision systems, although vision systems will not meet the ANSI (lighting)
requirements, they
work well for practical quality and industrial applications. These automated
systems offer customers the ability
to inspect most popular bar code symbologies.
No more slowing or stopping production for spot check
verification - This is an online, real-time inspection with input/output damage
controls. The Windows
based systems will store trend analysis data and provides full ANSI analysis
and is easy to calibrate. "The
Laser based Verification system will unequivocally resolve disputes between
trading partners", says Olson .
As noted above, most bar code printers verity.
Some only scan and read (beep) their
symbols only
occasionally and don't maintain a log of that inspection.
If you were sending your bar codes to retailers,
healthcare, airlines or DoD it would behoove you to have your suppliers of the
bar code symbols to inspect
every single bar code before being sent to you and insist on a log. One Minnesota
based Manufacturer is
fining their own manufacturing plants that send product with poor quality shipping
container labels to their
own automated distribution center. You must maintain a log (precise control)
of image-quality inspections
regularly to save a lot of fruitless searching when an irate customer insists
the bar code image doesn't conform
and wants compensation for his/her trouble.