Powder Coating Q&A: Powder Coating Assembled Parts

Q. We currently use an air-dry liquid paint. We want to powder coat our parts for better appearance and durability, but we are concerned about the high temperatures needed to cure a powder coating. Are there any powder coatings that can be cured at a temperature below 200°F? If not, do you have any other ideas about how we could cure a powder coating without causing damage to the sensitive parts?

A. The lowest curing powder coatings are in the range of 250°F and that is for epoxy resin systems that do not have good resistance to sunlight exposure. You will need a polyester resin system to get the ultraviolet protection. The lowest temperature polyester products will probably need to be cured at 325°F or higher, so I do not think low temperature curing is going to help with the heat-sensitive parts.

Consider coating all of the metal parts before assembly. I have done this with more than one manufacturer and had excellent success.This requires a lot of changes to the manufacturing process, but the results are so positive that it is well worth the effort. Parts are coated inside the areas that overlap in assembly, so no rust occurs between two parts that lie flat against one another. Holes have some coating in them, too, providing some additional corrosion resistance around fasteners. The powder coating is a thermal-set material, so it will be much tougher than most air-dry products. If you store parts outside in a yard, you will be impressed by how much better they handle sun and rain compared with its air-dry counterparts.

 

Originally published in the April 2016 issue.