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IndustryArena Forum > Manufacturing Processes > Milling > HELP! Newbie Having issues with ER32 tool pullout.
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  1. #1
    Join Date
    Sep 2020
    Posts
    2

    HELP! Newbie Having issues with ER32 tool pullout.

    Hi all,
    First post here
    I am a newbie to cnc Machining. We recently bought a machine to machine Aluminium moulds to make composite parts (Mostly small wings). Using 5mm diameter Ball nosed endmills at about 17k rpm we get great surface finishes. The problem is that during finishing passes (removing 0.2 to 0.4mm of material) the tool slowly pulls out of the ER32 collet and the cuts become deeper by the time it reaches the end of the part.
    I assumed that it would be impossible for the tool to pull out with such little loads? Are we doing something wrong or do we just need Hydraulic chucks?
    Does anyone have similar experiences?
    Thanks a lot.

  2. #2

    Re: HELP! Newbie Having issues with ER32 tool pullout.

    This suggests to me exactly what you are thinking that the collet in your chuck is not gripping the tool tight enough. Have you measured the length of the tool outside the chuck and confirmed that it is actually pulling out.

    Steve.

  3. #3
    Join Date
    Jul 2018
    Posts
    6248

    Re: HELP! Newbie Having issues with ER32 tool pullout.

    Hi Gian - Make sure everything is clean and fits correctly and the collet is the right size for the bit. Then tighten it up really tight. Also make sure it is engaged correctly. If it is not in far enough it will loosen. Peter

  4. #4
    Join Date
    Sep 2020
    Posts
    2

    Re: HELP! Newbie Having issues with ER32 tool pullout.

    Yes, The tool is pulling out, measuring it using tool length sensor and the change in tool length is consistent with the error in the actual part. My main issue is understanding the reason the tool is pulling out. The loads should be pretty low since its only a finishing pass. It seems impossible that I have to spend 600 bucks for a hydraulic chuck for such a light operation.
    I guess my next step is to try some high precision collets that only fit one size. The ones I have now have a range of 1mm
    Edit: we are already using high precision collets

  5. #5
    Join Date
    Aug 2009
    Posts
    1566

    Re: HELP! Newbie Having issues with ER32 tool pullout.

    ...try adding a plug/spacer in the bottom part of the collet ..(what ever size it is) so you compress the collet evenly at both ends of the taper.

    Attachment 449608

  6. #6

    Re: HELP! Newbie Having issues with ER32 tool pullout.

    I would switch to a smaller ER series like ER 16 or 11. At 17000 rpm you have a lot of mass spinning around a comparatively tiny tool. The near solid ER32 collet is a lot of mass dealing with a lot of centrifugal force at that rpm. Try a nice clean and dry ER 16 and see if that doesn't help. Look in the books for the proper number and tighten with a torque wrench. BTW - proper ER32 is 100lbs.

  7. #7
    Join Date
    Jan 2005
    Posts
    15362

    Re: HELP! Newbie Having issues with ER32 tool pullout.

    Quote Originally Posted by GianFerr View Post
    Hi all,
    First post here
    I am a newbie to cnc Machining. We recently bought a machine to machine Aluminium moulds to make composite parts (Mostly small wings). Using 5mm diameter Ball nosed endmills at about 17k rpm we get great surface finishes. The problem is that during finishing passes (removing 0.2 to 0.4mm of material) the tool slowly pulls out of the ER32 collet and the cuts become deeper by the time it reaches the end of the part.
    I assumed that it would be impossible for the tool to pull out with such little loads? Are we doing something wrong or do we just need Hydraulic chucks?
    Does anyone have similar experiences?
    Thanks a lot.
    ER32 for a 5mm cutter is crazy, you should be using no more than a Quality ER16 and torqued to the correct torque required then you won't have any problems, or better still a shrink fit tool holder no collet at all

    While the ER32 if a quality tool holder should work, if it is torqued to the correct spec's, the size of the ER tool holder the speed and centrifugal force is most likely releasing the collet grip on the tool

    .4mm is a loaded cut for a bullnose cutter .1 would be considered a light cut

    ER 16 slotted 42 ft./lbs
    ER 16 hex 42 ft./lbs

    ER 32 slotted 100 ft./lbs
    Mactec54

  8. #8
    Join Date
    Jun 2015
    Posts
    4131

    Re: HELP! Newbie Having issues with ER32 tool pullout.

    hy gian go with bearing nuts so to avoid useles torque on the collet ( that leads to micro-damage and less clamping force ), and be sure that the tool shank that goes inside the collet is blank ( thus not coated ), cilindrical ( no flats ), and mount it dry ( not only clean, but also dry), and use a H7 collet ( designed for a h7 clamping range )

    17k rpm : is there a balancing machine ? and what is the maximum rpm of your spindle ? you know, so to avoid killing your spindle at max rpm, with an unbalanced toolholder

    like other said, a toolholder with a smaller collet may help ... if it fails, and you wish to buy a hydra holder, it is no guarantee that it will work; consider shrink-fit ( definetly lighter than a hydra ) or weldon ( cheaper, possibly the screws will fly out, so craft another ones with small play, and adjust your cutting specs acordingly, because they deliver a higher tool run out, and that means that your final mould surface won't be as nice as when machining it with a tool with less run-out, but it may still be ok/salable )

    or it may be that your tools are poor quality : if possible, change them often / kindly
    Ladyhawke - My Delirium, https://www.youtube.com/watch?v=X_bFO1SNRZg

  9. #9
    Join Date
    Jul 2013
    Posts
    8

    Re: HELP! Newbie Having issues with ER32 tool pullout.

    Another tip I'd add if you go with the ER16 collet route with the bearing nut, is to use a 25mm deep socket attached to a torque wrench (if its a short stick out tool) so you could eliminate the variable of torque during experimental runs to investigate the issue. Cut a long slot and measure opposite ends for depth to see if it's still pulling out.

  10. #10
    Join Date
    Jan 2005
    Posts
    15362

    Re: HELP! Newbie Having issues with ER32 tool pullout.

    Quote Originally Posted by deadlykitten View Post
    hy gian go with bearing nuts so to avoid useles torque on the collet ( that leads to micro-damage and less clamping force ), and be sure that the tool shank that goes inside the collet is blank ( thus not coated ), cilindrical ( no flats ), and mount it dry ( not only clean, but also dry), and use a H7 collet ( designed for a h7 clamping range )

    17k rpm : is there a balancing machine ? and what is the maximum rpm of your spindle ? you know, so to avoid killing your spindle at max rpm, with an unbalanced toolholder

    like other said, a toolholder with a smaller collet may help ... if it fails, and you wish to buy a hydra holder, it is no guarantee that it will work; consider shrink-fit ( definetly lighter than a hydra ) or weldon ( cheaper, possibly the screws will fly out, so craft another ones with small play, and adjust your cutting specs acordingly, because they deliver a higher tool run out, and that means that your final mould surface won't be as nice as when machining it with a tool with less run-out, but it may still be ok/salable )

    or it may be that your tools are poor quality : if possible, change them often / kindly
    You have no clue the ER Bearing Nuts still need the same torque as a regular ER Nut, yes they work better and have a smoother lock up on the collet, so stop the Bs, they still need the same Torque to lock them up

    Nothing changes only a smoother lock up action with a ER Bearing Nut, there are 2 types of ER Bearing Nuts, Friction Nuts has hardened inserts which slide and the other has hardened inserts that work like a bearing

    The ones that last and work the best are the Hardened friction thrust washers, the bearing type fail after a short while of use, both types provide a higher lock up torque than a standard nut which should not be used for highspeed machining
    Mactec54

  11. #11
    Join Date
    Jan 2005
    Posts
    15362

    Re: HELP! Newbie Having issues with ER32 tool pullout.

    Quote Originally Posted by smartcolombyan View Post
    Another tip I'd add if you go with the ER16 collet route with the bearing nut, is to use a 25mm deep socket attached to a torque wrench (if its a short stick out tool) so you could eliminate the variable of torque during experimental runs to investigate the issue. Cut a long slot and measure opposite ends for depth to see if it's still pulling out.
    There is a set torque that you need to use for all collet types and size failing to use the correct torque will end in failure

    For High speed machining the ER Nut should have smooth out side which use's a special one way clutch wrench to lock them up this snip is from one of the many manufactures that manufacture highspeed ER tooling
    Mactec54

  12. #12

    Re: HELP! Newbie Having issues with ER32 tool pullout.

    Quote Originally Posted by GianFerr View Post
    I guess my next step is to try some high precision collets that only fit one size. The ones I have now have a range of 1mm
    What collet size you use? Internal diameter, I mean. I hope you are not using a 6mm one for a 5mm bit.
    I hold even 8mm bits with ER16 without problem but each bit is hold by same diameter collet.

    Maybe it's not the case but I noticed your quoted text about 1mm range. My 2 cents...

  13. #13
    Join Date
    Jun 2015
    Posts
    4131

    Re: HELP! Newbie Having issues with ER32 tool pullout.

    hy mactec, pls, be polite i was not refering to the torque required to tighten the nut, nor to that a bearing nut requires more/less torque to deliver same clamping force; in the end, each collet provider has it's own torque tables, that acts like a general guide line

    i was only scratching the surface of that a normal nut, in time, leads to collet and chuck damage, because it has a tendency to rotate the collet, while a bearing type won't change collet 'phase'; thus, a bearing type has a higher chance to transform tightening torque into clamping force, since there is less friction

    also, a low quality bearing nut won't behave as nice as a normal one crafted with more attention to thread tolerances ( including the thread on the toolholder )

    whatever / kindly
    Ladyhawke - My Delirium, https://www.youtube.com/watch?v=X_bFO1SNRZg

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