bmundy

Topic: Outgassing

Please someone help me!?

My problem: Outgassing on diecast aluminum parts.

We are powder coating a diecast aluminum part that has been milled/sanded on one side. That side is the only area we experience the outgassing on. I understand that the milling/sanding is creating our problem but we are kind of stuck with it. We have tried pre-curing the diecast parts (helps a little). We have also tried an additive to the powder (OGF), which by the way did eliminate the outgassing. but also dulled the finish of the powdercoat (unexceptable) which unfortunatly is Tiger Drylacs' Extreme Chrome which is a very reflective/gloss powder. This particular powder is the only color we experience the outgassing on & we spray about 40 different colors. Is there an additive that could be added the the cleaning process (rinse take for example)? We have a 5 stage washer 1st stage alkaline cleaner, 2nd stage rinse, 3rd stage phosphate, 4th & 5th stage rinse.

Thanks for any and all suggestions.

Brian

Travis Stirewalt

Re: Outgassing

Glad to help you Brian.

I have a few questions first.

1. When you say precuring... at what temp and for how long?
2. How heavy/dense is the substrate?
3. The Xtreme Chrome is by nature a high sheen product. Adding an OGF ingredient is probably not going produce a very desireable finish. Are you aware that the Xtreme Chrome should be clear coated as well. This usually dulls if applied to a dramatically undercured layer of Xtreme Chrome. We strongly recommend a full cure of Xtreme Chrome prior to clear coat. This increases gloss heavily.
4.I dont think that the pretreatment is necessarily your problem. I think it is the combo of outgassing, powder method and cure.

Give these questions a few answers and let me see what I can recommend ok.

Travis

Travis Stirewalt, CSI, NASF
Senior Sales Manager, Eastern US
TIGER Drylac USA Powder Coatings
www.tiger-coatings.com

bmundy

Re: Outgassing

The pre-curing is about 460deg for 18min. The part is a fairly light. We fully cure the Extreme Chrome before we apply the clear coat.

This part most always looks good "except" the side that has been milled/sanded.

Thanks for your help.


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Last edited by bmundy (02/19/2009 - 04:06 PM)

jfacciol

Re: Outgassing

Did you try impregnation of the die cast part before the plating and painting operations? Impregnation seals off the exposed pores of the die casting caused by the machining operation.

bmundy

Re: Outgassing

No we havn't. What are the specifics of the impregnation process ie. materials, cost, are there any chemicals to dispose of & the process itself?

Thanks for your response.