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Metal plating process on CRCA sheets before powder coating?

2007

I am doing the project on quality in process of rusting problems in CRCA sheets, Our condensing units are exposed to atmosphere in customer sites in which we are facing rusting problems. rusting occur with in two months, please tell me that clarification in whether it may happen with respect to process problem or environment.


I want some other questions regarding powder coatings
1) Is metal plating improves derusting and good surface finish?
2) Is film thickness of powder coating is a main criteria in rusting?
3) please give me the standard list of processes in seven tank process on C RCA sheets?
4) what is difference in metal plating and electro plating?

Kameswaraom
project trainee - Bangalore, Karnataka, India

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2007

Dear Mr Kameswaraom

I assume that you need a metallic layer beneath your powder Coating.
Am I right?

If you are interested in protecting your structure from corrosion I suggest you to go a zinc plating before powder
Coating. A thickness of 5 microns will be helpful.
Also I think your panels are rusted within two months.Then plese check the pre treatment before powder coating.
Hope that may help you a lot.

Regards,

Aurobind
- Aurangabad, Maharastra, India

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What is your present coating process (entire sequence, from cleaning to paint curing)?
Where does rusting originate? This should guide you to the coating's weak point. Rusting within 2 months suggests coating porosity.

Powder coating on steel is usually applied over iron phosphate (5-step process) or zinc phosphate (7-step process). For detailed information on phosphating, see Phosphating and Metal Pre-Treatment.

For the complete processing including painting, see Finishing Systems Design and Implementation (ISBN 0872634345). The Organic Finishing Guidebook & Directory (published annually by Metal Finishing magazine) is even more thorough.

Ken Vlach [deceased]
- Goleta, California
Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.
Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.
2007