Does carbide flex ?
Close
Login to Your Account
Page 1 of 2 12 LastLast
Results 1 to 20 of 25
  1. #1
    Join Date
    Aug 2014
    Country
    UNITED STATES
    State/Province
    California
    Posts
    4
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    0

    Default Does carbide flex ?

    I keep hearing during milling operations that "maybe the carbide is flexing ". As far as I know solid micro grain carbide doesn't flex. It is way too hard and brittle. I do high speed machining using very small tools .007,and even smaller. At the fees and speeds I am using if the took did "flex" it would probably be a matter of milliseconds before tool gave out.
    Any input is appreciated.

  2. #2
    Join Date
    Dec 2008
    Country
    UNITED STATES
    State/Province
    New York
    Posts
    9,127
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    2375

    Default

    Quote Originally Posted by vrodsteve View Post
    I keep hearing during milling operations that "maybe the carbide is flexing ". As far as I know solid micro grain carbide doesn't flex. It is way too hard and brittle. I do high speed machining using very small tools .007,and even smaller. At the fees and speeds I am using if the took did "flex" it would probably be a matter of milliseconds before tool gave out.
    Any input is appreciated.
    .
    yes carbide obviously flexes. if just does not bend very far before it breaks. window glass flexes too but bend too much it breaks.
    .
    a dull tool will flex resisting cutting. rerunning often will cut more than expected cause under less load its bending less and cutting a little more.
    .
    after you machine 10,000 parts if you record data you might notice trends. if you record nothing a person often will miss what normally happens especially if subtle hard to notice things. you are cutting with micro tools. you have the chance to collect data on actual results

  3. Likes JRIowa, Scottl, Oldwrench, muckalee, Bobw liked this post
  4. #3
    Join Date
    Jul 2006
    Location
    Hillsboro, New Hampshire
    Posts
    5,402
    Post Thanks / Like
    Likes (Given)
    1261
    Likes (Received)
    3760

    Default

    Yup, everything bends, no exceptions. How much before breakage, and how much force it takes to move it are the questions. With tiny carbide tools, they can bend a surprising amount before breaking, but go a little beyond their limit and it's goodbye.

  5. Likes Bobw liked this post
  6. #4
    Join Date
    Dec 2008
    Country
    UNITED STATES
    State/Province
    New York
    Posts
    9,127
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    2375

    Default

    size might matter a lot. fiber optic glass is tiny hair like and bends easily. obviously thick glass does not bend far before breaking

  7. Likes Bobw liked this post
  8. #5
    Join Date
    Jan 2005
    Country
    CANADA
    State/Province
    Saskatchewan
    Posts
    9,807
    Post Thanks / Like
    Likes (Given)
    1225
    Likes (Received)
    3413

    Default

    I drilled a few .010" holes using a carbide circuit board drill, viewing the operation under a microscope. Because the starting point was not well defined, the drill would sometimes wander on start. It was amazing to see how much that drill could flex. It would readily move over by as much as twice its own diameter and still drill a shallow hole successfully. I've also milled 1/16" wide slots using an .059 carbide endmill, and it would easily flex .003" because it would mill the slot to full width traversing the same toolpath in reverse direction with a spring pass.

    It's stiffer than HSS, but still not absolutely rigid. Mill a keyway full width with an endmill, it will always cut oversize if you cut both directions without any adjustment in Y.

  9. Likes Bobw, MattiJ, Strostkovy, crazygoat liked this post
  10. #6
    Join Date
    Jun 2006
    Location
    Near Seattle
    Posts
    4,484
    Post Thanks / Like
    Likes (Given)
    2610
    Likes (Received)
    1127

    Default

    I agree with everybody above, and add only this:

    Scale matters.

    For your 0.007" tool, a deflection of 50% of diameter before breaking would be a whopping 0.003'5". Which I don't think is visible to the naked eye. But when you measure your tiny feature on your close tolerance part with things like micrometers, that 3&1/2 thou will be obvious, and a problem.

    OK, so it won't bend 50%, it will bend 10% - 7 tenths. Which good instruments can measure.

  11. #7
    Join Date
    May 2008
    Country
    SOUTH AFRICA
    Posts
    1,458
    Post Thanks / Like
    Likes (Given)
    1051
    Likes (Received)
    600

    Default

    I will try post a pic tomorrow, it does but not very well... It's why for difficult situations I'd prefer HSS because it can flex a bit more before failure. Im speaking about drills here, it is insane that I am going into a pre drawn hole in rebar that is so far off centre it's scary and a HSS drill only took 100 holes to snap off and break some safety glass... But the carbide is lasting pretty well... And I can near guarantee that it will snap a lot "easier" that the HSS just with a small noise because of the stress that is involved. The carbide is flexing, I can see it while it's drilling but someone blessed this drill to keep it going

  12. #8
    Join Date
    Jan 2015
    Country
    UNITED STATES
    State/Province
    California
    Posts
    565
    Post Thanks / Like
    Likes (Given)
    85
    Likes (Received)
    289

    Default

    Quote Originally Posted by DMF_TomB View Post
    a dull tool will flex resisting cutting. rerunning often will cut more than expected cause under less load its bending less and cutting a little more.
    Yeah definitely the carbide is doing all the flexing in that example. Couldn't be the toolholder, workpiece, workholding, or the machine itself since those are perfectly rigid.

  13. Likes tdmidget liked this post
  14. #9
    Join Date
    Feb 2006
    Country
    UNITED STATES
    State/Province
    Indiana
    Posts
    12,260
    Post Thanks / Like
    Likes (Given)
    516
    Likes (Received)
    3356

    Default

    Engineers use modulus of elasticity or Young's Modulus (abbreviated as E) as the measure of stiffness. The English unit is millions of psi and the metric unit is GPa. There are many different compositions for carbide tools because of the binder content, with different values of E. But for a rough comparison, tungsten carbide tools are about two to three times as stiff as carbon steel.

    Larry

  15. Likes Oldwrench, sfriedberg, muckalee, eKretz, 9100 and 2 others liked this post
  16. #10
    Join Date
    Feb 2004
    Location
    peekskill, NY
    Posts
    23,898
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    4069

    Default

    [QUOTE=Milland;3176023]Yup, everything bends, no exceptions.

    Lies, nonsense!!

    Carbide is magic and does not obey the laws of physics. It has infinite Young's modulus and never ever flexes.

    Yep. True. I read it on the innernets.

  17. #11
    Join Date
    Jul 2006
    Location
    Hillsboro, New Hampshire
    Posts
    5,402
    Post Thanks / Like
    Likes (Given)
    1261
    Likes (Received)
    3760

    Default

    Quote Originally Posted by jim rozen View Post
    Yup, everything bends, no exceptions.

    Lies, nonsense!!

    Carbide is magic and does not obey the laws of physics. It has infinite Young's modulus and never ever flexes.

    Yep. True. I read it on the innernets.
    Don't you argue with me! I know the heads of the FBI, CIA, KGB (or whatever they call themselves this year), Boris Badenov, and Vladimir Putin's cat, and they'll all come to your house and beat you up if you cross me!

    In fact, they're waiting outside right now, so be polite and invite them in for tea. Then they'll beat you up.

    Now, if you'll excuse me, I need to go hug my dakimakura of Taylor Swift until I calm down. I am super-triggered right now...

  18. #12
    Join Date
    Jan 2007
    Location
    Flushing/Flint, Michigan
    Posts
    6,649
    Post Thanks / Like
    Likes (Given)
    287
    Likes (Received)
    5440

    Default

    Micro grain carbide will flex/bend more than conventional before breaking, part of the reason it is so popular.
    High cobalt grades will take more at a tradeoff of hardness or life.

  19. Likes toolmonger liked this post
  20. #13
    Join Date
    May 2017
    Country
    FINLAND
    Posts
    1,163
    Post Thanks / Like
    Likes (Given)
    308
    Likes (Received)
    547

    Default

    Quote Originally Posted by HuFlungDung View Post
    I drilled a few .010" holes using a carbide circuit board drill, viewing the operation under a microscope. Because the starting point was not well defined, the drill would sometimes wander on start. It was amazing to see how much that drill could flex. It would readily move over by as much as twice its own diameter and still drill a shallow hole successfully. I've also milled 1/16" wide slots using an .059 carbide endmill, and it would easily flex .003" because it would mill the slot to full width traversing the same toolpath in reverse direction with a spring pass.

    It's stiffer than HSS, but still not absolutely rigid. Mill a keyway full width with an endmill, it will always cut oversize if you cut both directions without any adjustment in Y.
    Same experience with small PCB carbide drills. 0.5mm carbide drill will flex suprising amounts. (just before it breaks)
    Typical 0.5mm PCB drill is maybbe 8mm to 12mm flute length so its pretty slender with 1:20 or so aspect ratio.

  21. #14
    Join Date
    Mar 2012
    Location
    Michigan
    Posts
    1
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    0

    Default

    Yes carbide bends. it will also yield and take permanent deformation. Not a lot like ductile materials. different grades behave differently. generally the more the cobalt the more the yield will be permitted. I've seen punches that look like bananas after use.

  22. #15
    Join Date
    Jul 2006
    Location
    Hillsboro, New Hampshire
    Posts
    5,402
    Post Thanks / Like
    Likes (Given)
    1261
    Likes (Received)
    3760

    Default

    Quote Originally Posted by jeff michael View Post
    Yes carbide bends. it will also yield and take permanent deformation. Not a lot like ductile materials. different grades behave differently. generally the more the cobalt the more the yield will be permitted. I've seen punches that look like bananas after use.
    Hmm - I've never seen a yielded carbide tool, but I don't deal with punches. What's the cobalt percentage in a typical punch?

  23. #16
    Join Date
    Mar 2005
    Location
    Northwest Indiana
    Posts
    3,632
    Post Thanks / Like
    Likes (Given)
    479
    Likes (Received)
    578

    Default

    Quote Originally Posted by jeff michael View Post
    Yes carbide bends. it will also yield and take permanent deformation. Not a lot like ductile materials. different grades behave differently. generally the more the cobalt the more the yield will be permitted. I've seen punches that look like bananas after use.
    Umm, don't think so if we're still talking cutting tools. I've seen tungsten carbide flex plenty of times. Never seen it take a permanent set. Shatters/snaps instead. Unless you're talking about some weird amalgamation that has WAY different percentages than a cutting tool.
    Last edited by eKretz; 05-23-2018 at 05:14 PM.

  24. #17
    Join Date
    Jan 2007
    Location
    wales.uk
    Posts
    1,144
    Post Thanks / Like
    Likes (Given)
    122
    Likes (Received)
    167

    Default

    Carbide does flex, but not a lot, I think what people are reporting as flexing is happening, but it’s the tool holder doing the moving, just my opinion
    Mark

  25. Likes Illinoyance liked this post
  26. #18
    Join Date
    May 2007
    Location
    Texas
    Posts
    1,658
    Post Thanks / Like
    Likes (Given)
    2397
    Likes (Received)
    295

    Default

    It could be then change a few tool holders to find out. I think carbide must have a rough and a sharp finish end mill to do the job. Pay attention to any taper in the z axis on the rougher. So both tools need to hold up if you want put in two finish end Mills each taking enough material if you are serious.

  27. #19
    Join Date
    Aug 2005
    Location
    Tucson AZ
    Posts
    6,092
    Post Thanks / Like
    Likes (Given)
    8510
    Likes (Received)
    2805

    Default

    Quote Originally Posted by Milland View Post
    Don't you argue with me! I know the heads of the FBI, CIA, KGB (or whatever they call themselves this year), Boris Badenov, and Vladimir Putin's cat, and they'll all come to your house and beat you up if you cross me!

    In fact, they're waiting outside right now, so be polite and invite them in for tea. Then they'll beat you up.

    Now, if you'll excuse me, I need to go hug my dakimakura of Taylor Swift until I calm down. I am super-triggered right now...
    Gonna stop by on the way to Don's place, Donie?

  28. #20
    Join Date
    Feb 2010
    Location
    ch
    Posts
    2,048
    Post Thanks / Like
    Likes (Given)
    187
    Likes (Received)
    269

    Default

    Quote Originally Posted by jeff michael View Post
    Yes carbide bends. it will also yield and take permanent deformation. Not a lot like ductile materials. different grades behave differently. generally the more the cobalt the more the yield will be permitted. I've seen punches that look like bananas after use.
    you have carbide punches? whats the idea?


Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
2