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Paint layer thickness measurement on composite

Paint layer thickness measurement on composite

Paint layer thickness measurement on composite

(OP)
Dear all,

I have a general question about paint layer thickness measurements on Glass/PPS (Poly Phenylene Sulphide) thermoplastic composite aircraft structures.

Does anyone know an accurate measurement method to define the paintlayer thickness on a PPS structure ?

Besides this question, I have second thoughts about the ability of a lightning strike layer on a composite structure underneath a thick painting layer to do what it is suppose to do: conducting lightning strike in a proper way.

Any remarks are welcome.

Andre

RE: Paint layer thickness measurement on composite

Do you need a non-destructive method?  If not, then a cross sectioned sampled should be mounted and polished, then observed with a microscope.  You can use a printed image, the magnification, and a rule to measure the thickness.

Regards,

Cory

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RE: Paint layer thickness measurement on composite

(OP)
I am looking for a NDO method Cory

thanx for your early reply

Andre

RE: Paint layer thickness measurement on composite

Paint does not interfere with the lighting protection. Lightning will blow through the paint and then the protection works as it is supposed to.

RE: Paint layer thickness measurement on composite

How thick is the paint?  There are ultrasonic systems that are supposed to be able to differentiate coatings (I think the coatings need to have a relatively high thickness, like greater than 100 µm) on a substrate.  Try GE Inspection Technologies and Olympus NDT.

http://www.geinspectiontechnologies.com/index.html

http://www.olympusndt.com

Regards,

Cory

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RE: Paint layer thickness measurement on composite

There is a device that scribes a line in the part.  Then you look at the scratch with a jewlers loop and verify prime and top coat.

This is the only direct measure that I am aware of.  I have tried inumerable NDT techniques and found them less than repeatable for the ranges required.

Another approach is to use a metal test coupon attached strategically to the part and use the coupon with an Isoscope to validate thickness.  I was able to sell this to Customer QA based on a comparison with the scratch technique.

Good Luck.  This can be a hard task to get through.

Composites and Airplanes - what was I thinking?

There are gremlins in the autoclave!

RE: Paint layer thickness measurement on composite

(OP)
We use a comparison test too, based on test strips.

However, in the field it is not usefull.

Cory, I hope that this equipement will be helpfull.

Regards,

Andre

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