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Thread: ceramic vs carbide

  1. #11
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    Quote Originally Posted by JoeLee View Post
    Since the ceramic insert cuts by melting then I would imagine you wouldn't want to flood it with coolant.
    Does any of the particals stick or weld themselves to any near by steel such as tool post, bed ways etc.
    What happens to part distortion due to the heat????


    JL...................
    The heat leaves in the chip. The part is cool to the touch. The chip, which is very fine, usually burns up before touching anything.

  2. #12
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    Cermets are not particularly fragile. They hold up very well, about as well as tungsten carbide inserts. The are fun to use on really hard materials and the finish left is spectacular.



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  3. #13
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    Evan that is quite a fire works display.

    JL.......................

  4. #14
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    Quote Originally Posted by Mcgyver View Post
    that's where i've seen ceramic inserts used, case hardened steel. I'm under the impression they are much more brittle than regular carbide inserts - is that fair to say?
    Ys, bump the corner to anything or tighten the screw holding it down too tight and crack. And dosn't like to be exactly on center, but a little tiny bit down. And whatever you do, don't face with it in the lathe, it will crack when the center approaches and surface speed drops to zero.

    The ceramics are used dry so that the material just ahead of the tool can heat up for the tool to work, the fireworks is pretty awesome, especially when the chuck jaws fling the burning chips around

    There are though inserts that have some stringy whiskers in it, some reinforced ceramic or something that handles the interrupted cuts well and can be used on a mill too.

    And the inserts I'm using are happy in the lathe if it is an interrupted cut like a little bit heat treatment warped piece - just up the RPM so that the heat generated is enough.

  5. #15
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    Ceramics are odd ducks. Jaako's explanation is pretty good.

    The inserts feel like lego's, and they do everything pretty much the opposite of the way you would use a conventional cutting tool.

    They get hot, and create heat and literally plasticize the metal ahead of the "cutter" and then just wipes it away.

    If you are chipping inserts, common sense would tell you to slow down, with ceramics.. means you are going too slow.

    Interrupted cut, milling or turning some hex stock, conventional wisdom tells you to slow down, with ceramics, speed it up.

    About 8 years ago I had some A286 parts to make, 275 of them, carbide endmills were taking 45 minutes for the first roughing op.
    Switched over to a 2" Kennametal face mill using some KY???? inserts, round ones, and my roughing time came down to 45 seconds.
    To get the inserts to work... 6000sfm, 11,400rpms, feeding about 250ipm in a ramping spinning spiraling pattern. I got three parts
    before rotating the inserts. It was wild, loud, obnoxious, fire flying everywhere, but it saved me a lot of time.


    Here is a pretty good article that helped me out a lot.

    http://www.mmsonline.com/articles/su...eramic-inserts

  6. #16
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    I have had good luck using ceramic and cermet inserts to face the clutch surfaces on flywheels in the lathe.

    A carbide insert has trouble with the inevitable hard spots which remain as shiny spots that can be felt with a fingertip. The hard spots dull the cutting edge which then makes the high spots even higher.

    A ceramic/cermet insert seems to hold up much better. The hard spots can still be seen but they aren't nearly as high. It is probably still not as flat as a grinding operation, but they seem to work ok.

    Dave

  7. #17
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    Oh and one nice thing about ceramics: they eat nitrided surfaces easily too Have made lots of mold parts from ejection pins that have been nitrided and used the ceramic inserts first to get down to the softer core. Goes like piss in the snow.

  8. #18
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    They are excellent for modifying bicycle parts too, especially sprockets.
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  9. #19
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    Thanks for the reply's, looks like they are to much for my lathe.
    The shortest distance between two points is a circle of infinite diameter.

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