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turning of hard materials & identify this insert

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  • turning of hard materials & identify this insert

    I'm not sure if its' carbide; it's bluer in color than the brazed carbide bids I have, and it doesn't compare to the non-coated carbide inserts I have. I tried turning a forged socket, and an impact socket (it's supposed to be tougher) - both with great success. Chips were not melting off like lava in the hard-turning videos on youtube. They were cherry-red on 30 thou depth of cut feeding forward, and non-colored feeding backward (i.e backing the tool out of the center in a face cut).

    I'll be making die holders from these sockets - too bad I don't have any boring bars that use this type of cutting material. All my carbide boring bars have failed to bore this material (no chips produced).

  • #2
    Hard to tell without a sense of scale in the insert photo. It looks like a CNMP or CNGP 432. I couldn't exactly match up the top form geometry (chipbreaker design) with any Kennametal, Iscar, Sandvik, Walter, Stellram or myriad others that I have on a Excel spreadsheet, but it's VERY similar to a Valenite SR form.

    If you wanted to have an insert that will do what that one does and be able to get one (or rather, a pack of ten) off the shelf, order Valenite CNGP432SR grade 9605. It's a sub-micron substrate carbide grade with a PVD-coating of TiAlN. I do believe that's what you have there.

    What kind of boring bars do you have? I can help you find something to cut the material.


    • #3
      It came with a Valenite toolholder - I'm just wondering what material/coating/treatments the insert is (i.e what gives it that blue color).

      My boring bars are cheap hobby ones with brazed inserts. I got a pack of some boring bar inserts with the toolholder that i'm making a boring bar for, but they're silver (like chrome), so I think they are strictly for cutting aluminium. Is this correct?

      One more question - why do these tool holders have a carbide piece underneath the insert (i.e why not just place the insert directly on the tool holder?) The insert has only one cutting face, so it's not to prevent damage to the tool holder.

      Last edited by Elninio; 09-22-2010, 06:35 PM.


      • #4
        I had enough success with standard inserts, but with just 1/3 of the recommended cutting speed.
        DOC 0.4 mm, feed down to 0.007 mm, Vc 50 m/min, tip radius 0.4.

        I know, the chip is way to small for the tip radius, but it worked the best. Surface was better than ground.



        • #5
          The carbide seats underneath the negative rake inserts helps with damping vibrations and supports the insert better than steel. That increased rigidity aids in longer tool life, usually.

          The blueish color is something related to the coating process. If it's a TiAlN, it would be almost black. A blueish color can be a AlTiN coating process.

          The shiny inserts are usually uncoated and polished after sintering. They will often have the periphery of the insert ground after polishing to give it a razor edge. If that's the case, the inserts are intended for (primarily) aluminum, but are also good for other non-ferrous metals, wood and plastics.


          • #6
            Carbide seats, one of the best inventions in the world. Wipe out an insert and you'll see why there is a carbide seat. It lets you buy a $10 seat instead of an whole new tool holder, and most of the time the seat doesn't really get damaged and you can just keep using it, but if you didn't have the carbide seat there, you would have been buying a new holder.

            Even better on inserted milling tools. Look at the shars ad that pops across up top, one of the facemills has carbide seats. It may be a bit more upfront, but it pays for itself with one little *oops*.

            As for the coating, most likely some version of an TiAlN. Colors vary wildly between manufacturers and even more so on inserts where there may be 3 or 4 different coatings on top of the carbide.

            You could search for years and never figure out what that insert is.

            Give Curtis a ring or e-mail at He can get you some good stuff at pretty dirt cheap prices and recommend you something that will work. I blew through interrupted cuts on almost 800 lbs of 17-4 that was over a 40C on less than $100 in inserts that he recommended. <--- shameless plug for a good guy that can save you money.


            • #7
              FWIW, this is a Valenite CNGP431 Sr grade 9605 that I have. You can see similarities, but I don't think they're the exact same insert.

              This grade and chipbreaker design works GREAT in tough materials such as high temp alloys, plus stainless steels and hardened steels up to about 60-62 Rc.