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Technical article
May 2016 54
The frame rate is synchronised with an
encoder and speed algorithm. The lighting
varies depending on the application.
The factors in consideration are the
reflectivity of the material, surface profile,
colour, line speed and camera type.
To ensure consistency in the images, the
setup features an enclosure to prevent
ambient lighting, outside particles, etc
from affecting the results. Vibration of
the cable is minimised by cable guides,
preventing images from being out of
focus.
An advanced algorithm is used to process
the images for cable wrap inspection. A
typical algorithm is capable of detecting
surface and wrapping defects such as
scratches, holes, uneven wrapping,
incorrect wrapping angle, tape peeling
and tape tears.
The algorithm requires analysis of the
pixels of the image and grouping them
for further interpretation. If a defect
is detected, an alarm will notify the
operator and an error report is saved to
the on-going data log. The defect will also
show up on the display for operators to
clarify.
3.2 Improving Quality Assurance
Suitable for any type of products: Since
the surface defect detection system with
accurate diameter measurement uses
machine vision, it can be used to inspect
the surface for many types of wrapped
products or convoluted profiles.
It is the most thorough method of
detecting wrapping and surface flaws
available and the advanced algorithm
can help classify the type of defects
accordingly.
Reduced defects: The system can provide
the operator with a view of current surface
images as well as both the most recent
defects with defect dimensions and the
current cable diameter. This continuous
stream of real-time information – especially
failure data – allows the operator to
isolate the causes of wrap imperfections.
Identifying when and how a defect occurs
will allow the technical staff to learn the
root cause of defects and reduce their
occurrence.
Quality assurance: The system will
continuously monitor the wrapping of
the cable for both overlap distance and
wrapping angle, and the measurements
can be recorded for later analysis. Images
of wrapping and surface defects are
captured and saved to a hard disk for use
in quality reports.
The wrap inspector system’s display makes
it easy for engineering and production
supervisors to examine potential defects
without having to see the defect on the
actual cable itself. Defect images are
saved together with location information
allowing operators to quickly find and
eliminate defects before they reach
customers or fail in the field.
3.3 Limitations
There are a few limitations to the wrap
defect inspection system:
• Sometimes significantly different
wrapping types will require
adjustment to the optical setup or
software changes
• Since the camera is looking at the
surface, water droplets/grease/dust
particles will be detected as defects
by the system. Generally, this can
be fixed with a well-placed air wipe.
Alternatively, the system sensitivity
can be decreased, which may result in
some of the smaller defects passing
through the filter
3.4 Test Results
The wrap defect inspection system is a
modified version of the surface inspection
system that is used in numerous
production lines around the world to
detect surface defects on wire and cable.
Some samples images of defects and wrap
measurements can be seen in Figures 1 to
6.
4 Conclusions
With a wrap defect inspection system,
imperfections in the wrapped cable
surface will be detected and the cable will
be wrapped correctly, to show overlap
distance and angle. The system provides
several benefits:
• Suitable for any type of wrapped wire/
cable and convoluted armouring
• Ensure the customer will not get
defective products, improving
customer relationship and confidence
• Reduce rework and eliminate cable
waste resulting in material cost and
labour cost
• Assist in internal improvement to
production process to reduce defects
• Ensure cable overlap n
Paper courtesy of the 64th IWCS Technical
Symposium, Atlanta, Georgia, USA,
November 2015
Craig Girdwood and
Andrew McCloskey
Taymer International Inc
Markham, Ontario
Canada
Tel: +1 905 479 2614
Email :
Website:
▲ ▲ Figure 1: Uneven wrapping
▲ ▲ Figure 2: Surface blemishes
▲ ▲ Figure 3: Tape peeling
▲ ▲ Figure 4: Tape wrinkle
▲ ▲ Figure 5: Armour puckering
▲ ▲ Figure 6: Discolouration