burky

Topic: powder coat over anodizing

We manufacture a product using aluminum extrusions and A360 aluminum die cast.  We are a meet AAMA 2604 and AAMA 2605 specification on our aluminum extrusions. We score a 9 (1/64" creepage on scribe) on the aluminum extrusions after 4000 hours of salt fog testing.  Our A360 aluminum die cast componets do not perform well.  We would like to meet 3000 hours of salt fog exposure scoring a 7 (1/16" creepage on scribe) on the A360 aluminum die cast parts as well.  We are having great results with our chrome free pretreat process on aluminum extrusion but our pretreat supplier is suggesting an off line chrome pretreat process for the A360 aluminum dia cast parts or anodizing prior to powder coat. 

I am looking for comments on anodizing prior to powder coating to attain 3000 hours of salt fog testing or a suggested pretreat process to get me there on A360 aluminum dia cast

AluConsult

Re: powder coat over anodizing

Hi

A360 is a difficult alloy to treat due to is high content of silicon.

Are you careful with your pretreatment before the chemical conversion coating (chrome free pretreat), so it doesn´t etch the surface and are you using a desmut with fluoride?

This is also important when or if you choose anodizing as a pretreatment. A lot of work has been done about anodizing as the adhesive layer before painting.

I have attached a paper about the subject. It gives you an idea of how many anodizing processes have been tried to find the best corrosion resistance.

Hot AC anodizing seems to be the most appropriate.

It works and you will have a higher corrosion resistance of your part than if you are using chrome free pretreatments.

Attachments: Click Here to See

Sunny regards

Anne


www.anodizingworld.com


Attachments:

   ADJcastings.pdf

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