M710iC noise

  • Hi All


    A Fanuc M710iC robot that I am interfacing to was working ok, except that there was a noise coming from the motors. J3 was making much noise and giving overcurrent alarm, and we changed the motor. The noise was less, and the alarm stopped.


    Since then it has got worse, to the point that the robot is unusable. Motors have been swapped repeatedy, new CPU, Servo and other boards have been replaced, to no avail. A complete software-reinstall was done too. Still no good.


    My feeling is that the PID values in the servo loop are wrong. Maybe too much gain. Perhaps the values are quite different to the default? Does anyone think this is plausible?


    The robot had been in storage for a few years, and the batteries were dead upon re-powering, so all the original config is lost. Is it easy to get the as-shipped setting from Fanuc?


    If you release the deadman, the noise stops. Press the deadman again, and as you take it out of fault the whiny noise starts again. It's hard to tell where it's coming from. Sounds like it's coming from all the axis motors. There is no program loaded, and nothing attached to the arm.


    It does seem to be centered around J3. If you lift the arm, it will jerk at first, then move. Perhaps the brake is not being properly released?


    Any ideas?


    Regards
    Roland

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  • Because you already changed the motor, I'm thinking internal cables of the robot.
    Try and switch cables from J3 with J2 and see if the noise is on J2.
    Or measure the resistance in the cable.


    When you replaced the motor, how was the grease looking? Black or brown/yellow?

  • Welcome to the forum Roland, I hope you find a lot of help here.


    The whiny noise is normal.. with that said, here is what is happening in normal operation. When the deadman is squeezed, the motor starts to get a pulse width modulated power signal applied to the 3 phases of the motor. This will emit a whiny sound, kind of like when you start to squeeze the trigger on a dewalt drill. The width of this pulse is a determining factor in the amount of torque being applied.


    You also stated that the controller batteries were dead. The as-shipped-from-factory is pretty close to what you have. When we get robots from Fanuc, there is a basic operating system installed but it means nothing and the robot is pretty much useless 'out of the box'. The controller options, software and the very important -library- must be loaded. This library has the kinematic data for your particular arm. Its what makes the cpu know the difference between an r2000 , m710, r1000 ..etc.. You hopefully have the data card that was shipped with the robot, it has the software to be loaded or a previous controller image backup ( not the regular 'all the above' backup) that you might be able to load.


    Let us know where you stand on these issues and maybe we can advise further.


    -Eric

  • Mhmmm every motor is different from another, also if is the same model, when you receive a new motor from fanuc you should receive also the new data to insert in the robot to manage the motor as well.


  • Mhmmm every motor is different from another, also if is the same model, when you receive a new motor from fanuc you should receive also the new data to insert in the robot to manage the motor as well.


    I have changed a lot of motors on Fanuc robots, and never had to read in other parameters. All servo parameters are connected to the type of robot, as chipprogr said. If correct software is loaded, correct servo param are loaded. I'm thinking a hardware faillure, not software....

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