Without getting into a rant, I had several pieces coated last week by a local shop. Was first told can't do chrome, then told they could. I bead blasted all parts prior to bringing in. After a couple issues with time frame and weather or not chrome could be done I got all the parts back. I looked at about half upon pickup and they looked great. Got home and found Triple's to have really bad "overspray" type defect. White specs in the gloss black.

Heres the prob! I returned and asked that the bad parts be redone. Guy says that powdercoating aluminum causes a safety issue because it is being heated. Guy adds that blasting powder off will leave marks in aluminum which will be noticeable when re-coated.

I call BS and reamed the guy. Guy says he will take care of it so he has the parts now.

1. Anybody heard of heat used to bake powdercoating being enough to weaken cast aluminum triple clamps?

2. Can powdercoat be blasted off without mangling my parts?

Thanks,
Steve

 

I thought powdercoat was only baked at around 400 degrees. I think I would get another opinion from another powder coater though.

 

man, wait to get the word from Joe, aka JRK5892. the man knows his $hit, and as far as powder goes, and all things two wheels. I take his word as bible.

 

Yes heat can affect the strength of aluminum and they should know what that heat range is before they do anything. Powder coating can be stripped off several ways without damaging the part. Anything from sand/bead blasted to a chemical stripping dip and even being burned off. But burning off brings up concerns of the heat limit again. I've worked in iron & steel foundry's for quite a few years and also did sand blasting for a local shop for several years also.

 

Aluminum melts @ around 1200 degrees F. 400 degrees isn't going to hurt it.

 

Ok...so why didn't you send them to Joe to begin with? Look at his work on his website. Freight is cheap compared to the price of parts. Just sayin...

 

Were not talking melt temps, it's called overaging. Take cast wheels for example, most are made from 356 t-6 casting alloy which is (heat treated)aged at 325 degrees. If you then heat it to say 400 degrees for 20-30 minutes it can actually overage and reduce the aluminums strength. Same goes for forged 6061 t-6.

 

Thanks Red Devil. It's good to learn something about the relationship between temperature and metal strength.

 

I'm no expert by a long shot, but after working in the foundry I've seen all types of metal react to heat & cold and you'd be surprised what can happen.

 

they need to be stripped, bead blasting is about the worst possible surface you can create to powder on, the worst... We chemical strip all our parts, it is much easier on the metal and will give a much smoother finish, no the heat will not mess with it, it is only 375-400* for about an hour max. then a slow cool down. i could see if you shocked the parts wiht a rapid cool but we do not
what you have on your parts is dust and crud from the drying rack stuff falling on it, would be my guess or not having a clean booth prior to shooting black... they need re done. we see this all the time, coaters make money in volume in parts, so they rip though as much as possible. the reason we are so busy is we do custom coating, each color run has its own set of parts, they are masked, plugged, prepped with the propper media per parts, and gives that glass smooth finish. there are good coaters out there bud just have to hunt for them. if you would like your parts re done we would be more than happy to help you

he is right about blasting powder off, not to mention it is a pain in the *** to do and takes forever, that is why we chem strip everything... plus if you are useing good media you do not wnat to contamidate it with paint blasts and crud from parts, we blast to create the perfect surface for powder, be that with black sand, steel grit, alum oxide, or custom blends... all depends on the part being shot.