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  Web
inspection systems apply to
paper, film, coating, non-woven,
textile, extrusion, metals and
other continuous web applications.
Web inspection systems have
historically used laser, cameras
or hybrid combinations of both
sensors as their core measurement
technologies.
Today, cameras are rapidly
emerging as the default inspection
solution in all but the most
specialized inspection applications.
Cameras success for inspection
is due to their continuously
improving price performance
ratio relative to other technologies
– especially when total
cost of ownership is considered.
Costs of inspection systems
vary dramatically based upon
customer defect criteria. For
example, there are simple camera
based inspection products that
use 5000 pixel Linear CCD arrays
and update at 1000 scans per
second. The signal from each
pixel is compared to a programmed
threshold. This information
is analyzed, scaled and sent
to a local or remote operator
display. Analog, serial, digital,
and limit-alarm relay outputs
are available to interface to
an alarm, a PLC or a SCADA system
for data archival/display. This
type of inspection product can
start with lighting for lower
than $10,000.
Conversely, inspection systems
that use high-speed parallel
cameras topologies to stream
data to a workstation that classifies
and displays defect images can
cost several hundred thousand
dollars. Engineered systems
are available that can obtain
cross web data arrays faster
than 1.2 gigapixels/second with
resolutions of 0.01 mm (0.4
mil), at speeds of 1000 mpm
(3281 fpm) and web widths ranging
from 50 mm (2 inches) to more
than 3,200 mm (~10.5 feet).
Defect information is displayed
in a convenient, ergonomic manner.
Defect classifiers are employed
that discern and segregate holes,
streaks, scratches, wrinkles,
edge tears, inclusions, gels,
particulates, bugs, dirt, oil,
watermarks, inconsistent formations
and other defects. Defect data
may be networked for production
and quality analysis to provide
product certification. Control
charting options to support
Six Sigma programs are also
readily available. Defects are
traced by their repeat length
correlating to specific roll
circumferences within the production
line to assist operators in
rectifying problem areas. Web
marking systems are available
to mark the web for future product
disposition. Defects may be
accumulated by cross web position
relative to slit lanes.
Because of the wide range of
customer defect types, web inspection
system capabilities and subsequent
system costs, we normally recommend
to develop organized defect
sample sets for preliminary
discussion and subsequent analysis.
Try to sort defect types in
order of importance to you –
separate defects into “must
haves” and “would
like” categories. Be aware
that system costs are driven
by a combination of web width,
defect size, defect contrast,
line speed, operating environment,
single or dual side web inspection,
number of different types of
defects, marking systems and
data links. Also, try to ascertain
what budget makes sense for
your defect “must haves”.
Contact
us - we are here to assist
you in this process. |
