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Thread: Stepper Motor Torqueless after 15 minutes of running in cmm machine

  1. #1
    caedrean Guest

    Default Stepper Motor Torqueless after 15 minutes of running in cmm machine

    Hi,

    My machine is a CMM type. This machine (it is driven by 3 axes- 5 phase stepper motors) has been running for 2 years and is fine. However, recently, some problems occur:

    1) Stepper motor loss torque after machine running for 15 minutes. When using multimeter to test for voltage at the power supply (this power supply is used to provide power for the 3 stepper drivers), the voltage dropped to very low value.

    2) When the motor/s is/are taken out (dismount from the machine) to rotate manually, rough rotation can be felt (unlike new stepper motor, is very smooth when rotates).

    Therefore, I believe that there is some problem with the driver/ motor, that caused excessive current being drawn from the power supply. This may result voltage drop in the power supply and caused the motor to lost torque.

    I'm not sure whether this assumption is correct. Please advice what will be the problem and how to solve it. Thank you!

    Best Regards,

  2. #2
    cnctech Guest

    Default

    I have several questions. Is it one motor or all that lose torque?
    Are all the motors the same size?
    If it is one motor that looses torque, can you swap two motors to determine if it is a motor or driver?
    If you swap motors and the torque loss stays with the motor then it is the motor, if it moves to the other motor then it is the driver.

    If the power supply voltage is being pulled down, then it might be a driver, because if the motor pulls down the voltage then you would probably get an alarm on the driver. But maybe not, depends on the type of driver and the age.

    Phil

  3. #3
    caedrean Guest

    Default

    Hi cnctech/ Phil,

    Thanks for the reply.

    All 3 motor loss torque together since the power supply drop to very low voltage value.

    Yes, you are right, the problem comes from the driver. There is a current cut trimpot in every driver, and therefore I adjust these 3 current cut trimpot in these 3 drivers to the minimum. When I run the machine again, the torque problem solved!

    How does the current cut trimpot affects the power being consume from the power supply? Any Idea?

    Best Regards,

  4. #4
    cnctech Guest

    Default

    I believe those trim pots determine the amount of current available to the motor for movement.
    Therefore if 1 motor is drawing too much current then cutting the amount of available current might keep the whole system from overloading. But, I think you will have trouble with 1 motor now instead of the whole system.
    Maybe not right away, but at some point. Then you will know which motor to replace.


    Phil

  5. #5
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    Default Re: Stepper Motor Torqueless after 15 minutes of running in cmm machine

    Where you buy your stepper motor and stepper motor driver?

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