Fanuc Parts Specialists

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Fanuc Alarm 31 Motor Incorrect Speed.

Motor did not rotate at the commanded speed. Either not rotating at all or rotating at very low speed. Fanuc Alarm 31 indicates the control section of the drive has detected the motor is not spinning/rotating or is rotating very slowly or erratically.

Fanuc alarm 31 indicates on the following series of drives.

When alarm presents stopped or moving slowly

  • If the motor rotates as slow speed (other than commanded) and alarm issue:
    • The motor phase sequence is incorrect.
    • Parameter setting is incorrect. Check associated parameter manual to spindle amp series.
    • Sensor feedback cable between motor and spindle amp is faulty
  • The motor is not rotating.
    • Speed sensor cable (feedback) or (sensor to motor term box) is faulty
    • Speed sensor is faulty. M, MZ, Mi, MZi spindle motor speed sensors.
    • The power lead is faulty (if spindle / winding switching is possible on machine)
    • The ALPHA or ai series spindle module is faulty.
    • Locking sequence for spindle is incorrect.

These are summaries of the Fanuc Alarm 31; we always recommend that you contact a trained CNC service engineer that is familar with the control and drive systems.

Fanuc Parts Specialist:

If your Fanuc spindle drive alarm 31; then we can help by assisting you with diagnosis and the supply of parts or repair of drivesmotors and control system boards. Further we can build cables on order if required.

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