CBN grinding in a VMC?
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  1. #1
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    Default CBN grinding in a VMC?

    I am currently trying to grind a .079 X .21 rectangle with .02 radius on all four corners. The machine is an Okuma M-560-v. My tool is a CBN ID grinding wheel with an OD of .19. I am radially stepping in .0005 at a pass and stepping down .005 RPM is 10000 feed is 18.1 IPM tool steel is 0-1 Rc 60-62

    Yes its taking a long time NO I don't care.

    Our CNC Jig Grinder is down possibly forever and I am trying to see if this is do able in an emergency when we cant wait for an outside vendor to make a punch for us.

    Thanks guys

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    Your SFM is way low; consider a 2" or 4" diameter cbn wheel arbor mounted.
    You can get the surface speed you need and don't get abrasive into your mill, at least not much.

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    Out of curiosity why are you grinding it? New endmills these days will cut 62R.C. easily, or just use a cbn endmill.

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    Haas does custom builds for GE Aviation.
    I have seen them being modified at the dealer.
    They run straight oil and have a fire suppression system and a hermetically sealed enclosure.
    They won't tell Haas exactly what oil they use, guess it's a trade secret.......

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    .0005 per pass for a CBN mounted point that diameter is huge. Chop that down by a factor of 10. Should be sub tenths per pass. If you had a solid 25k rpms maybe it would work decently. But 10k is just too low. Stick with a good hardmilling endmill. Ours can do 62rc. Also many other brands...

    Solid Carbide Hard Milling End Mills - MariTool

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    I hardmill all the time but this punch is .375 long and only .08 wide. I figured I would burn up a lot of punch blanks and end mills trying to get right so I am trying this. I have actually had some good results. Trying 15000 rpm now.

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    To me the radial step seems way huge and the depth per step way light.
    Think grinding and not milling.
    What did the old jig grinder do and run?
    Bob

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    Quote Originally Posted by CarbideBob View Post
    To me the radial step seems way huge and the depth per step way light.
    Think grinding and not milling.
    What did the old jig grinder do and run?
    Bob
    I dont know what the Jig grinder did I didnt run it. All I know is it took FOREVER to make a part. If I was surface grinding I would take more than .0005 in a pass and step over would be about 1/3 the width of my wheel. So you have a point with that my step down could be much greater.


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