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(hard) turning tungsten carbide

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  • (hard) turning tungsten carbide

    Was reading some academic jaddajadda about hard turning and what catches my eye was turning tungsten carbide.. Of course I had to try that like everything else that seems stupid:



    6mm carbide endmill shank reduced to 5mm. Crapped Sandvik CB50 mystery grade CBN insert re-sharpened on bench grinder& diamond wheel seems to work

  • #2
    Was the whole shaft hardened, or just the cutting end?
    At the end of the project, there is a profound difference between spare parts and extra parts.

    Location: SF East Bay.

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    • #3
      Originally posted by danlb View Post
      Was the whole shaft hardened, or just the cutting end?
      Its tungsten carbide, hard as hell. Cutting edge glows red at 60sfpm and ”cuttings” are heavy powdery stuff. Turning hardened HSS feels like butter compared to this.

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      • #4
        Originally posted by danlb View Post
        Was the whole shaft hardened, or just the cutting end?
        I would think a carbide end mill would naturally be hardened from end to end, from the sintering process. Is that not so? Do they undergo a hardening process similar to steels?
        Lynn (Huntsville, AL)

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        • #5
          Somewhat related crazy tech :https://www.precitech.com/about-us/p...ne/nanoformxtc

          Laser assisted turning where laser beam is guided trough the transparent cutting edge(diamond) to help soften the material under the cutting edge

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          • #6
            Originally posted by lynnl View Post
            I would think a carbide end mill would naturally be hardened from end to end from the sintering process. Is that not so? Do they undergo a hardening process similar to steels?

            Yeah, no need for hardening. Coating can be used to further increase surface hardness but even without that the carbide is really hard.

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            • #7
              LOL. I read that as tungsten cobalt. Totally different animal!

              Dan
              At the end of the project, there is a profound difference between spare parts and extra parts.

              Location: SF East Bay.

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              • #8
                Just be sure to contain the cutting dust and debris from the carbide. If that stuff gets inbetween the ways or other contact surfaces and embeds itself there.....well, you can guess

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                • #9
                  Originally posted by MattiJ View Post
                  Its tungsten carbide, hard as hell. Cutting edge glows red at 60sfpm and ”cuttings” are heavy powdery stuff. Turning hardened HSS feels like butter compared to this.
                  That's pretty neat, thanks for sharing. I still haven't tried any CBN inserts. Out of curiosity, have you considered trying the same at higher speeds?

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                  • #10
                    Originally posted by Yondering View Post
                    That's pretty neat, thanks for sharing. I still haven't tried any CBN inserts. Out of curiosity, have you considered trying the same at higher speeds?
                    "maybe" if I get enough big scrap carbide piece without better use. Besides recommended speed range for cutting tungsten carbide was considerably slower than HSS for example. 20 to 30m/min IRRC some numbers from insert brochure.

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                    • #11
                      Interesting, I guess that makes sense for cutting carbide. Correct me if I'm wrong - are these the same type of inserts used for "high speed machining" in softer (than carbide) materials? Or am I thinking of something else? I'm thinking of ceramic inserts that are intended to remove material from normal steels by high speed/heat shear rather than actual cutting, and I think they're usually white in color. Same thing or different?

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                      • #12
                        Originally posted by Yondering View Post
                        Interesting, I guess that makes sense for cutting carbide. Correct me if I'm wrong - are these the same type of inserts used for "high speed machining" in softer (than carbide) materials? Or am I thinking of something else? I'm thinking of ceramic inserts that are intended to remove material from normal steels by high speed/heat shear rather than actual cutting, and I think they're usually white in color. Same thing or different?
                        Sort of, except CBN (cubic boron nitride) is black in color and so expensive that its usually used only a tiny nugget on the tip of the insert much like diamond. Normal application is turning hardened steels, turning tungsten carbide appears to be quite rare and somewhat novel/academic interest still at the moment.

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                        • #13
                          My company does high precission carbide machining quite frequently. Mostly milling. They use carbide end mills with special coatings.

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                          • #14
                            Not only is the dust very abrasive, as already mentioned, but the cobalt binder is somewhat toxic.
                            I was lucky to get an Iscar cbn insert with a cheap job lot of inserts, unusually, it has four cutting tips, and came in it's own bespoke case. I haven't yet found a use for it.
                            I would think that CBN is not the preferred material for carbide, diamond grinding wheels are the correct solution.
                            Last edited by old mart; 03-27-2019, 04:52 PM.

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                            • #15
                              Originally posted by DEVILHUNTER View Post
                              My company does high precission carbide machining quite frequently. Mostly milling. They use carbide end mills with special coatings.
                              Intresting. I have heard about PCD and CBN endmills but didn’t think that coated carbide would do it.
                              Any examples/links of the endmils used?
                              (Google is pretty damn useless if you search for ”tungsten carbide milling”

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