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Thread: Carbide end mills, short life

  1. #11
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    Turn the mist off and just use the air blast to evacuate the chips from the cut.Like mentioned,re-cutting chips is the #1 way to lose cutting edges on solid carbide endmills.
    Other suggestion would be to check your chips to verify chip load.Just mic them for thickness,should be .0015-.002" on a two flute 3/4 diameter endmill.

    *IF* the chip load is correct and you are getting kind of twisted wide chips then everything is fine and it's probably just poor chip evacuation.

    *IF* the chip load is correct and you are getting short needle like chips,then it might be time for some spindle bearings.

    If all that checks out,then it could simply be the endmills you are using,maybe try a different brand or make sure the grade you are using is correct for the material.
    I just need one more tool,just one!

  2. #12
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    Hi,

    My first thought is the mister. With carbide endmills, flood or nothing. If you want better chip evacuation, straight air with no coolant will be best.
    If you think you understand what is going on, you haven't been paying attention.

  3. #13
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    Well, you've got a quality cutter and 'mist' is fine. I wonder sometimes if the naysayers for coolant on carbide have ever actually used it. The only reason I can think of is that they never really work the tool. With a good mister you can go high on the airflow for chip clearing if wanted, and whatever you need on coolant. I generally avoid fine 'mist' since it fills the shop and I don't like to run the evac blower when the air is on and its 108F outside.

    I'm sure you'd get better results with a 4-flute, and where possible a roughing cutter is much easier to work with for both the machine and chip control. You should easily be able to cut .3 deep in one pass with a good rougher. Truth is, mild steel isn't the greatest to mill and I do see improved cutting with coated edges.

    I use Rustlik WS5050 at 16:1 dilution and get great results on all carbon steels as well as 304SS and even aluminum. The only thing I don't use it for is tapping.
    Last edited by chipmaker4130; 08-18-2019 at 11:43 AM.

  4. #14
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    If I am reading this correctly, you are spinning an uncoated 2 flute endmill at 1000 rpm. You have a 100 thou depth of cut and an estimated .5 to 1 inches per minute feedrate.

    By the estimated feedrate, I'm guessing that you are feeding by hand.

    Comments:

    I think that both your depth of cut and feedrate are too low. Only engaging 100 thou of the endmill focuses the wear in that area. Engaging more of the flutes spreads the wear. You should be able to use half the diameter of the endmill as a starting point for depth of cut so in this case you could slot at full depth.

    Hand feeding always seems to wear endmills faster, likely due to inconsistent feedrates. If you have an auto feed, I'd suggest using it. If not, I'd practice maintaining a consistent and faster feedrate. This is easier to do with a smaller endmill. If you have one I'd try a half inch endmill.

    At .5 ipm your chipload is .00025, which is too low. You should be at least 4 times that. As another poster wrote, thicker chips remove heat from the part. So feeding faster both removes heat better and material faster.

    Teryk

    Sent from my XT1710-02 using Tapatalk

  5. #15
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    Images and/or video would be very helpful. I've only used carbide tooling on my lathe, without problems. I've used cheap Harbor Freight HSS 2 flute end mills on my mill/drill, usually at low speed, feed, and DOC, with hand applied coolant/lube.

    You might try an insert type milling cutter. A 16mm 2 flute cutter can be purchased for as little as $8:

    https://www.aliexpress.com/item/3283...chweb201603_53



    Inserts are just $15 for a lot of 10, from the same company (others as cheap as $4/1):
    https://www.aliexpress.com/item/3283...6890.subject_2


    https://www.aliexpress.com/item/3284...chweb201603_53
    Last edited by PStechPaul; 08-18-2019 at 03:15 PM. Reason: Better quality inserts (MZG)

  6. #16
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    Quote Originally Posted by PStechPaul View Post
    Images and/or video would be very helpful. I've only used carbide tooling on my lathe, without problems. I've used cheap Harbor Freight HSS 2 flute end mills on my mill/drill, usually at low speed, feed, and DOC, with hand applied coolant/lube.

    You might try an insert type milling cutter. A 16mm 2 flute cutter can be purchased for as little as $8:

    https://www.aliexpress.com/item/3283...chweb201603_53



    Inserts are just $4 for a lot of 10:
    https://www.aliexpress.com/item/3284...chweb201603_53

    Notice how dull the cutting edges are?
    12" x 35" Logan 2557V lathe
    Index "Super 55" mill
    18" Vectrax vertical bandsaw
    7" x 10" Vectrax mitering bandsaw
    24" State disc sander

  7. #17
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    You can't fully judge sharpness or performance from an image. I changed that image to one from the same factory, and it looks marginally better. But I haven't found many images of comparable magnification for higher quality (or brand name) inserts, although this might come close:

    https://rdbarrett.co.uk/product/apmt-milling-inserts/ (about 30 British pounds for 10)



    And, of course, you can always buy brand name inserts for the holder if the cheap inserts don't work as you wish. But AIUI carbide tooling is not and cannot be as sharp as HSS, or the edges will fracture. I'd risk $8 for a pack of inserts and just consider them expendable and a good value if they last long enough to get the job done.

    Discussion of honing (intentional rounding or dulling) of edges on carbide tools:
    https://www.practicalmachinist.com/v...e-prep-183359/
    Last edited by PStechPaul; 08-18-2019 at 03:45 PM. Reason: PM discussion

  8. #18
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    Quote Originally Posted by PStechPaul View Post
    ...https://rdbarrett.co.uk/product/apmt-milling-inserts/ (about 30 British pounds for 10)...
    I would certainly expect better quality from branded inserts at over ten times the price.

    My point is to avoid cheap crap.
    12" x 35" Logan 2557V lathe
    Index "Super 55" mill
    18" Vectrax vertical bandsaw
    7" x 10" Vectrax mitering bandsaw
    24" State disc sander

  9. #19
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    Quote Originally Posted by ezduzit View Post
    Notice how dull the cutting edges are?
    They are dull for a reason: durability. They cut steel just fine and hold up fairly well. If you get the same shape designed for aluminum they are sharp! The aluminum-type cutters are usually polished to a mirror finish too. I recommend against a cheap shank if you go this route. It is imperative that all the inserts line up correctly or you'll never get a good result. In the case of a 3/4" indexable endmill you will probably find more 3-'flute' than 2.

  10. #20
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    Oh, and yes the inserts designed for aluminum will cut steel and are often used for finishing. Roughing steel with them always results in excessive edge wear and greatly reduced service life.

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