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IndustryArena Forum > MetalWorking Machines > Fadal > Spindle motor problem
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  1. #1

    Spindle motor problem

    hi everyone
    in my vmc4020 spindle motor , i have
    increasing and decreasing rpm!
    in low speed gear only
    I don't have a problem when the spindle turns on at a speed higher than 2500, but this problem occurs when the speed is lower than 2500 when the spindle motor has more torque and speed.
    And the current protector shows that the motor is use too much current
    i checked vfd and swap with other vmc 4020 and i check encoder
    spindle rotates very smoothly
    i checked 3 wires and 2 ohm resistant together and 2 megaohm to motor body

  2. #2

    Re: Spindle motor problem

    If the motor is use too much current we can check below:

    1. Poor spindle lubrication

    2. Spindle bearing damage

    3. Spindle motor failure

    4. The spindle workload is too heavy
    http://cncmakers.com/cnc/controllers/CNC_Controller_System/CNC_Retrofit_Package.html

  3. #3
    Join Date
    Oct 2008
    Posts
    1639

    Re: Spindle motor problem

    That display looks pretty strange! I had something sort of like that where my low gear was bogging down and using lots of torque and surging. Mine ended up being the gear change cylinders weren't fully releasing keeping both speeds partially engaged. IOW, one of the belts was only partially releasing and causing drag on the motor. I bled the cylinder and it worked for a while then I finally just replaced both cylinders. I have no clue if yours is the same problem but might want to make sure that is working ok.

  4. #4
    Quote Originally Posted by rwskinner View Post
    That display looks pretty strange! I had something sort of like that where my low gear was bogging down and using lots of torque and surging. Mine ended up being the gear change cylinders weren't fully releasing keeping both speeds partially engaged. IOW, one of the belts was only partially releasing and causing drag on the motor. I bled the cylinder and it worked for a while then I finally just replaced both cylinders. I have no clue if yours is the same problem but might want to make sure that is working ok.
    thx for reply

    I checked the both of cylinders and I think they are working properly, the spindle rotates easily
    The problem shows itself in 1500 to 2500 rpm
    Attached Thumbnails Attached Thumbnails IMG_20240508_152320.jpg  
    Attached Files Attached Files

  5. #5
    Join Date
    Oct 2008
    Posts
    1639

    Re: Spindle motor problem

    On some Fadals, theres a delta / wye relay that controls which mode the motor is in depending on RPM. Maybe it has a bad set of contacts?
    Attached Thumbnails Attached Thumbnails DeltaWye.jpg  

  6. #6
    Quote Originally Posted by rwskinner View Post
    On some Fadals, theres a delta / wye relay that controls which mode the motor is in depending on RPM. Maybe it has a bad set of contacts?
    This machine only has an overload relay motor( allen bradly), which may not have worked when drag high current and the motor winding burn out

    I looked inside the motor with a flashlight, apparently some of the wires turned black and burned

  7. #7
    Join Date
    Oct 2008
    Posts
    1639

    Re: Spindle motor problem

    Well, there's your sign! Doesn't sound good.

  8. #8
    Quote Originally Posted by rwskinner View Post
    Well, there's your sign! Doesn't sound good.
    TNX for the info

  9. #9
    Quote Originally Posted by rwskinner View Post
    Well, there's your sign! Doesn't sound good.

    I found the problem, deassembly spindle motor with great effort and checked that all the wiring and bearings worked without problems ! I diassembly encoder and install again the encoder, the error increased tremendously, the pulse disk of the encoder was warped and scratched, which caused the pulse output to be wrong and the spindle driver vfd to be confused because of that! and sent a lot of current to the motor, according to the nxgenparts website, and then I replacing the encoder, the problem was solved

  10. #10
    Join Date
    Oct 2008
    Posts
    1639

    Re: Spindle motor problem

    I wasn't trying to be a smart ars if that's how you took it. I figured what you were describing was a cooked motor winding when you were talking about black, burnt wires. I'm glad you were able to fix it. The encoder was way cheaper than a new spindle motor.

  11. #11
    Quote Originally Posted by rwskinner View Post
    I wasn't trying to be a smart ars if that's how you took it. I figured what you were describing was a cooked motor winding when you were talking about black, burnt wires. I'm glad you were able to fix it. The encoder was way cheaper than a new spindle motor.
    Thank you for your advice

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