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IndustryArena Forum > MetalWorking Machines > Fadal > All VMCs.... lead screw's thrust bearing preload
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  1. #1
    Join Date
    Jul 2011
    Posts
    105

    Exclamation All VMCs.... lead screw's thrust bearing preload

    Greetings !

    How much backlash is allowed for AXIAL play for the lead screws ?

    We put new leads crews and bearings (and shim between them) but ... I can still measure 0,03 - 0.04 mm movement on the lead screws (basically all of them do this)
    I checked all the other possible places for movements but this seems the only reason why it has such a big play in the system.

    :bat: :drowning:
    FADAL VMC4020 HT 1995, Z 28" (if true) , 88HS , 10K rmp , 21 TC geneva /rotary/ , VH-65 (A-axis) ,3ph 400V , metric, NO conveyor, No palette. (+alternative DC AMP)

  2. #2
    Join Date
    Jan 2010
    Posts
    321

    Re: All VMCs.... lead screw's thrust bearing preload

    I ditched the 7304 bearings and shim and replaced them with proper ballscrew support bearings of the same dimensions. They come preloaded so just grease and install. Couldn't get less than 0.01mm using the 7304 and the new ball screw supports are less that .005mm

  3. #3
    Join Date
    Jul 2011
    Posts
    105

    Re: All VMCs.... lead screw's thrust bearing preload

    I see , but that is normal for FADAL to have this ****ty sollution ?

    What kind a bearing combo did u install (any number for those ?)

    Any modification on the machine to install ?
    FADAL VMC4020 HT 1995, Z 28" (if true) , 88HS , 10K rmp , 21 TC geneva /rotary/ , VH-65 (A-axis) ,3ph 400V , metric, NO conveyor, No palette. (+alternative DC AMP)

  4. #4
    Join Date
    Jan 2005
    Posts
    15362

    Re: All VMCs.... lead screw's thrust bearing preload

    Quote Originally Posted by pilot001 View Post
    I see , but that is normal for FADAL to have this ****ty sollution ?

    What kind a bearing combo did u install (any number for those ?)

    Any modification on the machine to install ?
    He is not talking about what you have on your machine something completely different

    You should have a preload on your Thrust Bearing in your case it is adjusted by the shims, you should have zero movement from the Bearings if it is assembled correct and preloaded
    Mactec54

  5. #5
    Join Date
    Jul 2011
    Posts
    105

    Re: All VMCs.... lead screw's thrust bearing preload

    Stange...

    So that shim... that was provided by the supplier... (0,35mm) is not sufficient ?


    .
    FADAL VMC4020 HT 1995, Z 28" (if true) , 88HS , 10K rmp , 21 TC geneva /rotary/ , VH-65 (A-axis) ,3ph 400V , metric, NO conveyor, No palette. (+alternative DC AMP)

  6. #6
    Join Date
    Jan 2005
    Posts
    15362

    Re: All VMCs.... lead screw's thrust bearing preload

    Quote Originally Posted by pilot001 View Post
    Stange...

    So that shim... that was provided by the supplier... (0,35mm) is not sufficient ?


    .
    I'm sure there are variation's in machine manufacture and the shim most likely should be adjusted to suit, so it looks like you need a .3 or less to remove your Backlash, that is if it is in the Bearings if it is floating in the housing then you have to do some work with the end cap, they have many different spacers and shims
    Mactec54

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