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Powder Coating thickness for various steel parts

July 6, 2009

Hi Finishing.com,

I am producing a custom bicycle and need to powder coat the steel I'm using before I can ride it around. The frame is primarily made from mild steel (1018) and I have a few parts machined from 1045 on a cnc lathe. What thickness should I be using for each type of steel (1018/1045)? What about the weld points? Should I do any special prep (extra grinding, etc) to insure that the powder coating will adhere nicely to the welded areas? Finally how much plugging/taping do I need to do on threaded portions? Would it be okay if I just chased threads later or should I be completely blocking these portions off from the powder coating process? Most threads are M5 X .8 metric threads and none of the threads are fine-pitch. Is there are suggested, cheap method to keep threads from rusting if they don't get a layer of powder coat?

Thanks!

Adam

Adam Kay
product designer - San Francisco, California

Hi, Adam. I wouldn't worry too much about the thickness; thermosets (paint-like coatings) would generally be about 0.002-0.003" per layer unless you have difficult-to-cover corners and such.

Yes, the welded areas should be ground smooth because the powder will not fill every tiny nook and cranny welding pit, and bridging them is not satisfactory.

Plugging and capping is generally easier than the alternatives, but yes, you can chase the threads.

The steel needs a phosphate treatment before powder coating, and a high quality zinc phosphate treatment can afford at least a little protection for the threads.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
July 6, 2009