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Turning Tungsten

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  • Turning Tungsten

    Does anyone have any idea's as to what type of tooling I need to cut and knurl tungsten rod? I've tried HSS and Carbide tool bits. Carbide shatters and HSS doesn't even make a scratch in it. I've thought of trying Ceramic Cutters, but I'm open to suggestions.

  • #2
    I suggest you make cutting tools of the tungsten. It's hard stuff but diamond might work. From what I've read it's more commonly pressed and sintered from tungsten dust.

    Ken

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    • #3
      Apparently you are trying to machine Tungsten Carbide. Pure Tungsten is fairly soft and easy to cut.
      About the only way to work with Tungsten Carbide is a diamond grinding wheel.

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      • #4
        My old "Machining Fundamentals" book says that pure tungsten can be machined with carbide if you preheat to about 400 deg.F. If so, you could keep a torch played on the backside of the workpiece while cutting with a carbide parting tool. Knurling might be a problem if you cannot find carbide cut knurling tools.

        RWO

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        • #5
          Pure tungsten is reasonably easy to machine. Tungsten carbide is not machinable with any common or even uncommon tooling. It is ground to shape with diamond tooling. In most cases tungsten carbide tooling and other shapes are made by hot pressing to either net shape or very close to net shape. Tungsten carbide tooling is made using tungsten powder with cobalt metal as a binder. It is pressed in molds at the fusing temperature of cobalt. When recycled it is heated to the melting point (liquidus) of cobalt which is then spun out of the powder to recover the tungsten for reuse.
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          • #6
            This appears to be a good example of using the wrong terminology. Pure Tungsten is virtually useless except for incandescent bulb filaments and vacuum tube electrodes. So every one has to guess what the material actually is.

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            • #7
              I have 100+ pounds of coarse tungten carbide like they use on oil drilling bits. About the size of roof granules. Any idea where to sell it for more than scrap? This is not a offer to sell. It's a want ad for info.
              "Let me recommend the best medicine in the
              world: a long journey, at a mild season, through a pleasant
              country, in easy stages."
              ~ James Madison

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              • #8
                Pure tungsten is sometimes used for ballast blocks on aircraft.
                When I was working at a helicopter completion center we would occasionally have to install tungsten ballast blocks.
                Usually the ballast would be secured using existing fastener locations, so we would mark the locations and send it over to the machine shop
                to be drilled and reduced to the required weight. Never heard any complaints about it being difficult to machine.
                Last edited by dfw5914; 03-27-2013, 11:29 PM.

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                • #9
                  Sintered tungsten carbide can also be machined via EDM.

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                  • #10
                    Pure Tungsten is also used for guide rods in semi auto pistols to add weight. It is very dense and heavy.

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                    • #11
                      Unless some special characteristic of pure tungsten is needed it makes no sense to fight with the stuff. It's hard and brittle and needs to be ground to final size if finish is important. Fortunately, industry has a solution, W/Ni/Fe alloys, which are nearly as heavy, but quite machinable. Here is an example: http://www.mi-techmetals.com/products_tni.htm. I deal with parts made from this stuff regularly, and have seen it machined.
                      Last edited by Optics Curmudgeon; 03-27-2013, 11:52 PM. Reason: spellin'

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                      • #12
                        Sintered tungsten metal was used extensively as a shielding material in transfer cases for radioactive isotopes, particularly cobalt 60. Atomic Energy of Canada routinely machined various sizes of spacers from tungsten stock purchased in England. I was told that it machines somehat like cast iron, but I think they used carbide tools. I have one of those spacers, so I might have a go at it tomorrow. Stay tuned.
                        Duffy, Gatineau, Quebec

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                        • #13
                          Pure tungsten is sometimes used for ballast blocks on aircraft.
                          It was also used as ballast blocks on the Curiosity Mars Lander/Rover. Just before atmospheric entry it ejected two 165 lb tungsten ballast weights which left craters easily visible from orbit. That unbalanced the landing craft so it would trim it to provide lift in the air. After entry it ejected another six 55 lb blocks to rebalance it. They left more craters.
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                          • #14
                            Which form is used as welding (TIG) electrodes? Whatever it is, it's pretty darn hard.

                            -bill

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                            • #15
                              Thank's for the info, I'll be definitely be using your suggestions as well as the link that you provided.
                              I should have mentioned in my original post that I'll be producing match grade dart's for friends and other client's.

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