Fanuc 10M motor

[gowthu]

In St60 Lathe (slant bed) x axis motor gets over heated.It takes 5 amp at idle and 7 to 8 amps while moving.Hydraulic oil gets heated upto 55 deg C.X axis counter balancing is Single port hydraulic cylinder.Kindly suggest to troubleshoot cause for high current in x axis motor.

[Dan Fritz]

Does the motor have an electric brake in it? If so, the brake could be dragging or not releasing at all.

Many Z axes (on mills) and X axes (on slant-bed lathes) use brakes to keep the slide from drifting down when you turn the power off. When the power is on, the brake is usually released electrically. Sometimes the brake is separate from the motor, but most of the time it's built right in to the motor to save cost.

The current going to a servo motor is almost directly proportional to the load on the motor. Even when the motor is not moving, current is required to just hold the motor in position. Any servo must "hunt" a little to maintain position, so a motor that is fighting a stuck brake is drawing excess current even at rest.

Other possible causes are bad lubrication, bad ballscrew or thrust bearing, counterweight not working, etc. My bet is on the brake.

[gowthu]

Actually there is no separate brake on the motor.Only there is a hydraulic plunger to hold the motor when power is off.i also want to know why the hydraulic oil getting heated and it is the cause for loading of motor.because the motor current also goes up with increase in oil temperature.also please suggest me how to check up the in built brake of Fanuc Dc servo motor- 10M model.

[Al_The_Man]

It sounds to me like the hydraulic counter balance needs adjusting, specially if it is drawing current in idle. You should have a pressure relief valve, set it while monitoring minimum current on the motor at idle.
If you have the Lock pin that goes in when off, it probabally does not have an electric brake.
Al.

[gowthu]

x axis motor armature rewinding done twice and poles also refixed twice.is efficiency of the motor get reduced?winding and pole removal routed out only when over heat alarm observed in the machine.

Thanks