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#21
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Powder Coat on 4130
On Mar 22, 8:29 pm, "Phil" wrote:
Hello Was watching American Chopper this evening , I see things on that show that make me cringe but I do enjoy the antics of that family, they always refer to Pipe if they are building a frame out of Tubing etc. , this evening they were working on a dragster bike for NAPA and when it came time to paint the machine they said that powder coat couldn't be used because of the heat involved would ruin the 4130 tubing , seems like a lot of engine mounts and other A/C parts will have to be junked , would like to hear some thoughts on this concept , as an A/C welder it is of interest to me. Thanks Phil Lohiser EAA 12873 The thing about powder coating aircraft structure, is that the places that do it are not controlled as well as FAA designated shops. Some might do it right, and some, well.... Also, there is a big difference in steel vs aluminum, as the temperature involved (~400 F) does not harm 4130, but might heat treated aluminum, especially if the shop doesn't pay close attention and gets the temperature much higher during the process. Most 4130 tube aircraft structures use normalized 4130, so there is no heat treat to worry about. Aluminum is almost always heat treated, so there is an issue. It is a fact that 10 years or so ago, a scuba diver had his aluminum tank powder coated when it started looking bad, and when he was having it filled, it exploded killing one guy and causing another to have his leg amputated. If the structure doesn't use heat treated steel, you are probably OK. Powder coating heat treated aluminum is a definite no no. Bud |
#22
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Powder Coat on 4130
On Apr 1, 4:16 pm, John T wrote:
Responding to an "old" thread here, but powdercoat cures at about 400 deg. F. ---------------------------------------------------------------------------------------------- Whoa. 'Powder-coating' is a generic term that applies to everything from ceramic frits to vinyl. The temperature/atmosphere needed to cause the powder to melt and flow together can be anything from 150 degrees to over a thousand degrees. Key point here is that all 'powder coating' is not the same. Some shops use but a single type of coating, say a urethane. Others may offer a variety of coatings, from low-temp vinyls to chemically inert epoxies. You CAN do it at home -- it is easier than applying ceramic thermal barrier coatings. But you have to know what you're doing. Most of the information (and mis-information) commonly available has to do with vehicular applications done mostly for the sake of appearance, most of which have no place anywhere on an airplane. But it's the cat's pajamas for things like a battery box, cabin fixtures and the like. -R.S.Hoover |
#23
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Powder Coat on 4130
On Apr 8, 3:26 pm, " wrote:
On Apr 1, 4:16 pm, John T wrote: Responding to an "old" thread here, but powdercoat cures at about 400 deg. F. ---------------------------------------------------------------------------*------------------- Whoa. 'Powder-coating' is a generic term that applies to everything from ceramic frits to vinyl. The temperature/atmosphere needed to cause the powder to melt and flow together can be anything from 150 degrees to over a thousand degrees. Key point here is that all 'powder coating' is not the same. Some shops use but a single type of coating, say a urethane. Others may offer a variety of coatings, from low-temp vinyls to chemically inert epoxies. You CAN do it at home -- it is easier than applying ceramic thermal barrier coatings. But you have to know what you're doing. Most of the information (and mis-information) commonly available has to do with vehicular applications done mostly for the sake of appearance, most of which have no place anywhere on an airplane. But it's the cat's pajamas for things like a battery box, cabin fixtures and the like. -R.S.Hoover Excellent points. If someone tries to use a 1000 deg temp process to powder coat a heat treated steel part, then the heat treatment will almost certainly be lost, as even some of the highest strength, high temperature alloys start to lose temper at as low as 800 F. Also, the chemical reaction caused by exposure to high tempearture and the presence of the materials that are being used to "powder coat" the steel could cause God knows what to the surface of the steel. Hydrogen or nitrogen embrittlement comes to mind. For lightweight structure that your life depends on, you need to KNOW. Many builders have their 4130 steel parts annealed after welding by heating the structure to a cherry red temp and slowly reducing the heat, in order to relieve any stress concentrations created during welding. People that have powder coated normalized 4130 probably are OK, even at 1000 F, but you never know for sure until a chemical study of the effect has been done. Bud |
#25
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Powder Coat on 4130
John T wrote:
Your definition of powdercoat is too broad. Its generally accepted that powdercoat in the powdercoat community refers to a plastic like powder that transforms into a solidly linked coat at temps between ~300-400F (the coatings generally start flowing out at about 300F, but need to cure at about 400). Urethanes and ceremic coatings are not considered powdercoating. Doing powdercoating at home is quite doable, but you need to but a powdercoating gun and colors. You also need an electric oven you won't be using for food. You can get these and read forums on powdercoating at eastwoodco.com. Powdercoating isn't just for looks. Like paint, it protects surfaces, but as has been mentioned, its heavier than paint. Its stronger than paint though. Generally accepted by whom? The Powder Coating Institute, a national trade organization for the Powder Coating industry doesn't seem exclude urethane based or ceramic components. Since Eastwood bills itself as providing "unique automotive tools and supplies, as well as expert advice and solutions, for the classic car and hot rod enthusiast" I would expect the enthusiasts that hang out there and utilize Eastwood's "DIY" home shop equipment would be more limited in their capabilities. It is of interest that Eastwood quotes PCI as well. PCI technical briefs cover powders that flow and or cure at 250F to over 1000F, as well as those that are UV cured. I think maybe your definition is too narrow. The fact that multiple definitions may exist just highlights the need to verify the process and the shop in question before making any decisions. Charles |
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