specific kind of welder

[Harry B. Sprott]

Andy

Recently I saw an old Popular Mechanics Newsreal which showed a kind of hardfacing technique which allowed the used to actually spray a weld over a lady's hat, coating it in metal. What process is this and what kind of welder do I need to buy to do this. I restore automobiles and do metal art, and this would be so usable to me in certain areas. Please get me an answer.

Harry Sprott

[Tanner]

I know the technique is called metal spraying, and that an oxy/fuel torch is used. Beyond that, I'm no help. Try a deep search on Google.com for "metal spraying" and see what happens. Good luck.

[klsm54]

Flame Spray welding is done in one of two processes, Hot Spray, and Cold Spray. The hat being covered was obviously cold spray. The main difference is that in cold spray the base material is not heated. In hot spray, the base material is heated so you get more of a weld, than a coating.

There are many different powders available. Some for build-up, some for hard facing, and in various metals. There are also ceramic powders and even plastic powders that can be applied with the same equipment. Equipment runs the gamit from a small canister that will fit on your combination torch hadle and feed the powder through a brazing tip, to fancier set-ups that are capable of spraying both processes and all kinds of powder that will cost you $1,000 to $1,500 for a hand held set up.

Cold spray is typically applied while the piece is in a lathe and being turned, while hot spray can be very localized and applied to stationary parts.

Eutectic and UTP ( now Bohler Thyssen) are two companies that I have worked with. If you can find a distributor that handles either of these brands, they should be able to give you some information

[aametalmaster]

I have the Eutectic set up complete but never used it. I have like 6 or 7 powders and the torch set up. It was made in 1962 but never used...Bob

[MAC702]

There are several variations of thermal spraying, primarily grouped into three processes: flame spraying, arc spraying, and plasma arc spraying. I would imagine all the thermal spraying techniques are the "hot" type that klsm54 spoke about.

Some of them are quite fascinating. Like the arc spraying process that uses two wires, at different polarities and they hit each other right in front of a jet of compressed air.

One use is for building up shafting in a lathe, or otherwise restore dimensions to worn parts. Also, adding corrosion resistant surfaces in salt-water environments. If the material to be sprayed can be had in wire form, then the electric arc or flame spray can be used. If only a powder is available, then it has to be flame or plasma spraying.

You can spray things like metal wires or powders, ceramic powders, and ceramic or plastic rods.

[paulrbrown]

The Eutectic torch setup needs to have the material getting sprayed heated to 400 degrees....I bought one thinking it was coldspray????I does take some fideling with, but you won't be able to spray flammable materials, I tried spraying a lathe bed, but it was a very large heatsink so the material just could not get up to temperture and the spray would not adhere. On smaller stuff, it does adhere very well, has a textured apperance like 120 grit sandpaper.Good Luck, Paul

[ASKANDY]

All great answers and too bad MILLER sold off it's Thermo spray business a few years ago or I would have specific product numbers for you. Many companies build these things depending on requirements. You sound like you need a small unit but even small thermo spray units can get pricey.

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