Problem SERVO Stalls at High speeds


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Thread: SERVO Stalls at High speeds

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    Default SERVO Stalls at High speeds

    Hello Everyone. I am currently working on a Wood CNC machine - PROTEC EXCEL 4016TC by the Manufacturer BIESE. The drill (the spindle) is controlled by a servo motor and recently it has been stalling when direct speed commands of +4000rpm are given to it. In order to achieve high speeds +6000rpm or up to 18000 rpm we now bypass the problem by programming a speed progression of 1000-->2000-->3000 and so on till we attain maximum desired speed. Does anyone have an idea why the servo would start stalling when a direct command is given to it?

    PS- The controls are achieved Yaskawa equipment

    Thanks

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  2. #2
    Community Moderator Jim Dawson's Avatar
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    Default Re: SERVO Stalls at High speeds

    It sounds like the VFD is going over current on acceleration. Extend the acceleration time a bit. If this was working in the past and is now giving problems, there may be a problem with the spindle motor.



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    Default Re: SERVO Stalls at High speeds

    eliteautomation

    Is the servo motor a direct drive, or through a Gear-Box, if a Gear-Box check the Gear-Box has the right oil and is free to turn

    Ac or Dc

    Mactec54


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    Default Re: SERVO Stalls at High speeds

    Quote Originally Posted by Jim Dawson View Post
    It sounds like the VFD is going over current on acceleration. Extend the acceleration time a bit. If this was working in the past and is now giving problems, there may be a problem with the spindle motor.
    Yaskawa servo motors don't use a VFD for a drive

    Mactec54


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    Community Moderator Jim Dawson's Avatar
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    Default Re: SERVO Stalls at High speeds

    Quote Originally Posted by mactec54 View Post
    Yaskawa servo motors don't use a VFD for a drive
    You are correct, I should have said drive. But that would also indicate that the ramp rates are controlled by external software. I'm going to go with a motor problem.



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    Default Re: SERVO Stalls at High speeds

    Thanks all for your valuable answers. As troubleshooting steps,
    1 - Asked the operatoer to start the machine at a high speed. Noticed an "overtorque" message on the drive ( the drive is a Yaskawa CIMR-G5C4011)
    2 - I inhibited the overtorque setting/alarm then asked the operator to start the motor at a high speed. The spindle turned without any problem. At a second start attempt it stalled. Third attempt it stalled. fourth attempt it started without stalling, but there was no error message on the drive.
    3 - I also observed that, when a command of say 6000rpm is given to it, the G meter indicates vibrations of 10-12g and it stalls. When the same speed is attained by programming accelerations of 1000rpm to 2000rpm to 3000 rpm right up to 6000rpm, the vibrations do not exceed 5g.

    Concerning the spindle motor, I also feel it is probably faulty as most of you suggested so i am planning to check it's bearings probably. Not sure if the encoder would have taken a hit too.



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SERVO Stalls at High speeds

SERVO Stalls at High speeds