10-4: Wire, Optical Fibre And Cable, In Line Surface Quality ...

Wire, Optical Fibre And Cable,
In Line Surface Quality Measurement And Defect Detection (SQM):
Presentation Of The Development Test Results
(Second Development Phase).
Jean François Fardeau, Sébastien Gathier
CERSA-MCI, R&D division,
Cabries, France
+33 4 42026044 · sales@cersa-mci.com
Abstract
This presentation continue the previous one made for IWCS 2005
on basic principles and applications. The present one describe the
progresses and present expectations after the first prototype
development and experimentations.
‣ The bad news is the SQM is not still ready for sale.
‣ The good news is that it already can works for some
applications at lower frequency and the technology we need to
get the full performance is available and will be included soon.
After running the first prototype, it appears we had to adapt the
initial target to the technology limitations while keeping customer
expectations.
Some applications, need turn frequency at 200kHz, but accept 60
only dots per turn. This is already a far better resolution than all
existing instruments for surface defect detection.
Others, need high resolution, up to 200 dots per turn, but frequency
significantly reduced, down to 80kHz.
The SQM principle presented last year is now made. It was used for
technology capability evaluation in realistic condition. We have
been now able to quantify the needs and seek for the right
technologies for each case. As some aspect are still confidential it
limits detailed presentation.
Fig 1 Prototype
Keywords: Surfaces; quality; roughness; blisters; lump; neck;
plating; plated; colour; defect; detection; measurement; wire;
enamelled; fibre; fibber; colouring; line; coating; cable; bonding;
gold; stainless steel; tungsten; molybdenum; copper; titanium;
aluminium.
1. Remembering
In applications where surface quality (roughness) or fine defect free
is critical, like special fine wires, gold wires, wire plated, coatings or
optical fibre colouring, enamelled copper wires, broadband cables,
but also large diameter cables or plastic tubes, there was no
instrument for high resolution and high-speed whole surface quality
check and analysis.
The present existing lump and neck detectors are either based on
optical shadows with several parallel beams checking at local
diameter fluctuations. These approach is very limited for whole
surface check. It is difficult to detect fine defects and impossible to
detect cracks.
The SQM covers all the surface of the small wires at high
resolution, with line resolution below 0.1mm and circumference
resolution down to few microns.
2. Surface quality below 2mm diameters
According to the diameter, the production speed differs as well
for metallic wires, optical fibre and extruded products. That lead
to specify the sufficient instrument performance according to the
application and present technology capabilities.
This instrument works like a “ring” camera with CR number of dots
per turn (ring) at certain “ring frequency” making a complete image
of the surface when the line move.
We collected the following maximum characteristics: OD and LS.
Fig 2 Basic instrument performance expectations
OD
mm
LS
m/s
LS
m/mn
NB
Dots
CR
mm
CF
kHz
LR
mm
0.1 40 2400 48 0.007 333 0.12
0.2 40 2400 48 0.013 333 0.12
0.3 30 1800 48 0.020 333 0.09
1 30 1800 96 0.033 167 0.18
2 10 600 96 0.065 167 0.06
3 10 600 96 0.098 167 0.06
OD: Outside diameter; LS: Line Speed; NB Dots: Number of
measurement dots per circumference; CR: OD-Dot corresponding
Circumference Resolution; CF: Circumference Frequency; LR: Line
Resolution (line move between 2 circumferences).
We determined the number of dots (NB) and the circumference
frequency (CF) to match a sufficient performance with technology
International Wire & Cable Symposium 327 Proceedings of the 55th IWCS/Focus

capabilities for each type of applications. This meet the customer
demands and becomes our present target. It meets high resolution
for very high speed lines with LR (pitch) below 0.15mm at
2400m/mn. This is especially important for enamelled wires, optical
fibres and fine extruded products.
Nevertheless, other characteristics can be made, especially for
surface quality of metallic wires where frequency is not critical but
resolution might be much more important.
We define a basic rule for instrument design: NB * CF = K with K
about 16000. ex.: 48x333 or 96*167, etc…due to the present
technology limitation. But the products terms could also be NB =
200 and CF =80kHz.
We also have to consider that there is limited interest to increase the
number of dots for very fine wires. For 0.1mm and 48 dots, the dot
pitch is 0.12 mm and dot size (CR) is 7µm. For NB=200 it would be
1.5µm with 4 time less energy (smaller dot size). In that case surface
quality should be excellent (gold, polymers, …) to keep continuous
signal. For most of the cases, micronic surfaces are not perfect. That
means it is better to integrate larger dot surface for better signal
quality and defect sensitivity.
Below 0.3mm OD, it covers fine wires, optical fibres and fine
extruded products. From 0.3 to 3mm it is more in the common
product sizes for wires, POF and extruded products.
As the light energy reflected by the wire is proportional to the
diameter, below 0.1mm it becomes very weak. That leads to seek
higher light transfer efficiency, specific light sources, sensors, but
mainly sensor amplification.
Fig 3 instrument principle
Photo-sensor A
Ring of
elementary
light sources
Zone 2
Zone 1
Measurement
area
With “i” = incident light energy density. 2*dθ is the sensor
aperture, then constant and determine the dot size on the
wire.
Fig 4 Reflected light on the wire
Fig 5. Light energy distribution
E
Sensor
aperture
120°
r
OD
When the light source point rotates around the wire, the sensor
received an energy varying in “cos” shape on ±.60° on the wire.
For this instruments it is difficult to get significant results without
the basic test structure, which is the electronic, optical banc and
sensor systems. This is why we made it running first in order to be
able to get the results in the right conditions.
Fig 6 Instrument design
θ
θ
2*dθ
dθ
Wire
Zone 3
Glass tube
Photo-sensor B
Photo-sensor
Source/Photo-sensor
locations
Zone 1/ sensors A + C
Zone 2/ sensors B + A
Zone 3/ sensors C + B
Scheme n° 1:
Energy scattered by the wire in the θ direction for dθ:
E = r*dθ*Cosθ*i
Ring of light sources
Sensor systems
Fig 7 Realisation
International Wire & Cable Symposium 328 Proceedings of the 55th IWCS/Focus

This present design work today at lower frequencies for diameters
above 0.5mm.
Our next step, by October, November 2006 is to include a new light
source to significantly increase light energy density and new sensor
technology at high speed and much higher sensitivity to validate the
capability to measure below 0.1mm.
3. Typical in line applications
3.1 Wire industry:
• Surface quality (roughness), for gold, stainless steel,
tungsten wires.
• Plated wire to detect missing plating area.
• Coated wires or fibres, to detect lump and neck or missing
coating.
• Enameled wires for blister detection
3.2 Optical fibre industry:
• Coating defect (lump and neck).
• Coloring line, to detect defects, missing coloring layer.
3.3 Cables:
• Insulated wires and small cables (broad band): lump and
neck, local defects.
4. Development plan and marketing
The present works lead us to plan the last tests within now few
months and the first industrial tests early 2007.
The first sales are expected end of for first quarter 2007, one year
later than our initial expectations.
International Wire & Cable Symposium 329 Proceedings of the 55th IWCS/Focus