Ask the Expert Question-and-Answer Archive

by Ron Joseph

February, 2007

Bowing of Aluminum Extrusions During Powder Coating

Q: We are currently experiencing a bowing issue on a painted aluminium extrusion / mild steel panel frame assembly. When we put the frame together before painting, everything is ok. When we paint and take the final assembly off the paint plant the aluminium extusions are bowed. If we break/crack the paint seal between the aluminium extrusion and the mild steel panel the the bow disapears.

The paint we are using is Powder coating Epoxy Polyester baked approximately 20 mins at 190° C

Please advise.

A: I'm not sure that I fully understand your question. If I have interpreted it correctly, the problem might have little to do with the powder coating, but more so with the expansion/contraction of the aluminum versus the mild steel when you place the assembly in the oven. Can you possibly powder coat the aluminum extrusions and the steel frames without physically attaching them together? If you need to have them attached, can you do so after the metals come out of the oven?

Please get back to me with your answer.

Hope this helps.

Regards,

Ron Joseph