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Powder coat adhesion

2007

We are using a ASTM B633 Type 2 RoHS compliant Zinc plate on a chassis that our Powder coater is suggesting there is a problem with the plating and why the powder coat is flaking off.

Paint is Sherwin Williams PLT2-00228 texture polester TGIC Chemical coating.

Any thoughts regarding if the bake temperature for the paint could be at issue for this new RoHS type of plate?
Any thoughts at all?
Poor plate
poor paint

Thanks

Need to try to pinpoiunt the problem and am at a loss at the moment.

Sean Halloran
KAL Tool - Webster ny usa

2007

Odds are very good that it is a RoHS induced problem, Sean. Manufacturers took several different approaches to reaching acceptable corrosion resistance without hexavalent chromate conversion coats, and the principal focus was corrosion resistance rather than compatibility with powder.

Ask your plater if he is using a 'thick film chromate' as this is very compatible with the temperatures and it does not involve a topcoat. I am not here to discourage those who went the thin film plus topcoat route instead, but I think the thick film route is an easier path to good powder coating adhesion. Then write it all off as another hidden cost of RoHS.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

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