1. AFGM Conference in Chiang Mai 2007
Advanced vision systems for Quality Control in glass manufacturing
Robert Mortensen,
Sales Manager, JLI vision a/s
AFGM Conference in Chiang Mai 2007

2. Agenda General tech. considerations Glass tubing Tableware
Container Glass
Final remarks
AFGM Conference in Chiang Mai 2007

3. Technical considerations
Components that make up a vision system:
Engineering and software
Cameras
Lighting
Mechanical design
Integration and support
AFGM Conference in Chiang Mai 2007

4. Technical considerations (cont.)
Cameras:
Chip type (e.g. Matrix, line-scan, CCD, CMOS)
Resolution
Pixel-sensitivity of chip
Exposure time
Examples of exposure time (linescan):
Std camera……………… 1/19000 sec
Advanced cameras…… 1/30000 sec
JLI second gen.………… 1/58000 sec
Lighting:
Structured lighting
Arranging the lighting itself
Light source
Mechanical Design:
Choice of physical components
Physical constraints on production floor
Power supply
Line speed and stability
AFGM Conference in Chiang Mai 2007

5. Technical considerations (cont.)
Integration:
Running in the system
Calibration and adjustment of tolerances
Surveillance:
Software based monitoring system
Measures e.g. temp., voltage, fan RPM, HD conditions
Training:
User training both on-site and long distance
Optimal use and first line support
AFGM Conference in Chiang Mai 2007

6. Glass tubing
Optimal design is 100% circular with even wall thickness and defect free
Diameter versus line-speed: diameter x speed = constant
Exposure time
Speed up to 12m/ sec
defects down to .02 mm
Motion blur – rule: max movement 1 pixel pr. sec.
Light source
Centering
Depth of field: critical for front- and back-end inspection
AFGM Conference in Chiang Mai 2007

7. Glass tubing (cont) Defects – stones, knots and airlines
Examples of windows for tube-end inspection:
Figure 1 – Window Dimensions
Figure 2 – Window Region of Interest
Defects – stones, knots and airlines
Stones are inclusins, typically refractory material
Knots are lumps from badly dissolved glass
Airlines is air trapped in pockets at the mandrel
AFGM Conference in Chiang Mai 2007

8. Glass tubing (cont) Mode of detection
Stones and knots are found by detecting black inclusions refractory material
Knots are lumps from badly dissolved glass
Airlines, down to 3micro meters, are detected using high resolution CCD cameras and a very power full light source.
Clusters of faults can be detected in a predefined area
100% defect-free tubes
Main challenge is very thin airlines
JLI developed Off-line system to cover this market
AFGM Conference in Chiang Mai 2007
Figure 3: Examples of thin airlines
from the JLI Offline system

9. Tableware Different forms and sizes – issue with diffraction
Market caracterised by large number of different models – especially stemware has a complicated range of shapes.
Different forms and sizes – issue with diffraction
Vision inspection demands different and often complicated masks
The Dynamic Light Box – JLI
Uses background lightning with pattern composed of light/shadow
Enhances the type of defect that needed to be highlighted
Defects like mould rings, waves and cracks can only be detected in this way
Specific patterns are syncronised with production to achieve max. Intensity
Geometry measurement – bright uniform background with mask following the profile of the glass. Accuracy is 0.1 mm
AFGM Conference in Chiang Mai 2007

10. Tableware (continued)
Dynamic Light Box (cont.)
Easy to install, reliable, and very adaptable solution to detect and measure geometry
Principle shown below
Figure 4:
The Dynamic Light Box
AFGM Conference in Chiang Mai 2007

11. Container Glass Both hot- and cold-end inspection
Handling restriction in hot-end
Dimensions measured with an accuracy down to 0.1 mm
Wall thickness measurement by tight control of measurement loop. Accuracy 0.01 mm
Change in production parameters shows up on dimensions
Efficient way of monitoring production, e.g. via trend graphs
Figure 5: Birdswing detected by
backlightning
AFGM Conference in Chiang Mai 2007

12. Final remarks
The glass industry has many challenging inspection applications and it is always a challenge to provide practical solution to this market segment.
Even highly automated glass-factories need continued surveillance in order to maintain their high quality level.
A vision system provide you with the following advantages :
More accurate and stable quality control
Continued 100% inspection
Improved production flow
Fast feedback from production and automatic data logging
In order to keep a high and consistent standard of their products in todays marketplace our customers have acknowledged that investing in advanced vision technology may be the only viable way
AFGM Conference in Chiang Mai 2007

13. Khob Khun Krub Tee Hai Kawm Ruam Mue
(Thank you for your attention )
AFGM Conference in Chiang Mai 2007