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  • spray welding powder torch

    Is anyone up on this technology?

    How much does it cost to get in to it? Do I just need a torch and alloy?

    My goal is to apply a "rough" finish to a shaft, sorta like knurling, but not that mechanical. What I want is a gripping surface, much like sandpaper, but durable. I remember getting things hard chromed and the surface being rough, I believe spray welding is the proper term, I do not know.

    I believe this is what is used to build up shafts, then machine back down, but I'm not sure how durable the coating is in it's virgin form.

    How much should I expect to pay for the powder? How much powder would it take to do a 1" diameter shaft that is 3 feet long?
    Last edited by snowman; 05-06-2008, 02:31 PM.

  • #2
    There is a process that sprays carbide on things like brick saws and the like.

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    • #3
      The one we used to use was a plasma spray
      see: http://en.wikipedia.org/wiki/Plasma_spraying
      "Those who hammer their guns into plows will plow for those who do not."~ Thomas Jefferson

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      • #4
        i have a couple of them that are made by WELCO, a division of someone. . . i also have a small container of powder but. . . i have never tried it. i have had a machine shop (far larger than mine) spray a hydraulic ram and build it up for re-sizing for me twice in the past 4 or 5 years and its a very nice job that they do. first they turn down the surface making it kinda ruff and threaded looking, then spray it in the lathe while rotating. then they turn it down to size, with a super good finish for hydraulic sealing at 10,000 psi hydraulic pressure. i don;t have the balls to do it on my lathe.

        the instruction book sez its easy and the demo guy actually built up cast iron that had disappeared intothe great darkness of rust. . .

        someday i must try it on something worthwhile. the little bottles of powder are quite costly, like $30 for a double shotglass full. . . . . altho when you do it on a lathe, they say to use something to catch and recycle what you overspray.

        (unedited)

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        • #5
          do you know how far the little bottles go?

          I'm not trying to build a surface up, just trying to treat the surface

          thinking about just knurling though

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          • #6
            I don't know about the ones with powder, but I experimented with a "metalizing" metal spray system about 30 years ago that used wire. It consisted of an electric-powered spray "gun" that hooked up to an air compressor, acetylene and oxygen tanks (from a gas welding unit) and had a built in electric wire feeder. Any metal that you could get in wire form of the appropriate gage could be sprayed. The workings were simple. The wire was fed into an oxygen/acetylene flame inside the gun where it was melted and an air blast sprayed the molten metal onto whatever surface you had, even wood . . . and no, it didn't char the wood as the metal spray was instantly chilled upon contact with the wood. The sprayed surface was built up with continuous passes exactly like sprayed paint. The finished surface comes out as a very fine matte granular surface that is very pleasing. It looks like a fine sand casting.

            This process is often seen on race car and hot rod exhaust manifolds and is also used to build up crankshafts and other components prior to re-grinding. As I recall, the gun wasn't all that expensive, like $1,500 back then.

            Planeman

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            • #7
              Snowman, there was a thread awhile back, I think on PM forum by Mike C. He had started a new job and was trying to master one of the metal spraying processes.
              James

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              • #8
                yeah, i finally found it....took me a while to figure out the keywords for searching.

                looking at the costs, it seems that I'm much better off just knurling. I was hoping it would be easier, but the metal just seems to expensive.

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                • #9
                  Metalizing guns,Eutectic made them,dunno if they still do.My experience has been sometimes yes and sometimes no(YMMV).

                  I had an idea once of using a masking method to produce a perforated plastic film, then wrapping that around a shaft and using a chemical etchant to leave bumps on the surface.Never tried it,just went ahead and knurled the shaft.
                  I just need one more tool,just one!

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                  • #10
                    I have one of those old Eutectic spray outfits.
                    Only tried it once...got the shaft red hot like they say and buggered it...lol!
                    I tried it in the middle of a flimsy shaft... it warped...duh!
                    Anyway.. I think how long the little jars would go depends on which one you use. A few of them are really heavy and would go a fair ways.
                    Come on over for coffee and you can try this one
                    Russ
                    I have tools I don't even know I own...

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                    • #11
                      Originally posted by torker
                      I have one of those old Eutectic spray outfits.
                      Only tried it once...got the shaft red hot like they say and buggered it...lol!
                      I tried it in the middle of a flimsy shaft... it warped...duh!
                      Anyway.. I think how long the little jars would go depends on which one you use. A few of them are really heavy and would go a fair ways.
                      Come on over for coffee and you can try this one
                      Russ
                      Eutectic still make the stuff, there are two main processes, hot and 'cold' spray. The hot requires getting the parent shaft or whatever near to red heat, the 'cold' works at a lower temp but doesn't bond quite so well & seems to need closer control over the variables. It's often done in the lathe (the cold spray).
                      I've got the gear for both, come up quite cheaply sometimes on ebay if you're prepared to wait, but never tried the cold process. The hot process is a good way for joining or repairing cast iron, can also be used for hardfacing. I think they've restricted the range of powders quite a bit because of health & safety concerns, also less demand.
                      There are some more exotic processes for industrial/manufacturing situations, see the Eutectic website.

                      http://www.castolin.com/wCastolin_com/products/

                      Tim

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                      • #12
                        Spray welding

                        I too have the set for doing this. We also have it a work but I never used it. Others have. Salesman instructor showed us how and told us who where it is used. PennDot used to coat the edges of their mower blades and snow plows with one of the metals and get up to 5 times the life span of the edge finish. Cost depends on which metal you use. Plain ole iron was cheap and cobalt was way out of my price range the last time I check. Cobalt was something like $95 per lb! and that was several years ago.

                        Cold welding refers to keeping the heat at or around 500* as compaired to up to 1200* for red hot steel.

                        mark61

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                        • #13
                          Eutuetic makes the systems still. Spendy.

                          It really is an art to use one of the things. If you dont know what you are doing you will warp the crap out of what you are coating.

                          Welco is a division of Harris.

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