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Tecnatom
Tecnatom has more than 50 years of experience providing services, equipment and systems devoted to NDT testing in several sectors and markets.

1133 views
21:38 Apr-07-2009
Mathew Anderson
Ultrasonic Thickness Gauge

Can Ultrasonic Thickness Gauges measure the thickness of glass, and if so will only the higher end models do this?

Regards

Mathew

 
22:21 Apr-07-2009

TomNelligan

Engineering,
retired,
USA,
Joined Nov 1998
390
Re: Ultrasonic Thickness Gauge In Reply to Mathew Anderson at 21:38 Apr-07-2009 (Opening).

Yes, any good ultrasonic thickness gage should be able to measure glass with a proper transducer and setup. You didn't indicate the range of glass thickness that you need to measure, but inexpensive corrosion gages will typically measure flat or large-radius glass over roughly the same range in which they would measure steel. You will need to calibrate sound velocity for glass, although it's usually close to that of most steel alloys. Precision gages can do much more, including wall thickness of small diameter tubing using focused immersion transducers.

We have an application note on the subject that you may find useful:
Thickness Measurement of Glass
http://www.olympus-ims.com/en/ndt-application/183-id.209715251.html

 
03:05 Apr-08-2009

Neil Burleigh

Sales
Krautkramer Australia Pty Ltd,
Australia,
Joined Dec 2002
146
Re: Ultrasonic Thickness Gauge In Reply to Mathew Anderson at 21:38 Apr-07-2009 (Opening).

To follow on from what Tom has said we would need to know a little more about the measurement application. We have had an interesting application recently regarding laminated glass windows that were installed the wrong way. The thin thickness was installed to the outside instead of the inside which meant the impact resistance was not as stated. We used a 10 MHz probe to measure the thickness of the glass to the laminate which was supposed to be 6 mm whereas it was 3 mm.

hope this gives some insight.
Regards

Neil Burleigh

 
06:00 Apr-08-2009

Michel Couture

NDT Inspector,
consultant,
Canada,
Joined Sep 2006
813
Re: Ultrasonic Thickness Gauge In Reply to Neil Burleigh at 03:05 Apr-08-2009 .

This method is often used on aircraft windows. The windshields are laminated, so a little bit harder to do, but it can be done. I remember for the Bombardier Challengers, we had an actual step wedge made from the same material as the window. Made the job so much simpler.

I don't know about other situation, but for aircraft, since the windows are made of something similar to lexan or plexiglass, they can be blended if they are scratched. So it is important to know the exact thickness. If I remember correctly, you can only remove 10% of the thickness. But like Neil said, 10 - 15 MHz with a delay shoe should do it.

 


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