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IndustryArena Forum > General Manufacturing Processes > Milling > HELP! Newbie Having issues with ER32 tool pullout.
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  1. #1

    Join Date
    Sep 2020
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    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
    Member
    Join Date
    Jul 2018
    Posts
    1891

    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
    Member
    Join Date
    Aug 2009
    Posts
    716

    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
    Member
    Join Date
    Jan 2005
    Posts
    11553

    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

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