Fanuc 18M - 414 HCA Servo alarm only while cutting

[shrirang]

We have a Kao Ming VMC with Fanuc 18M controller. I get a
414 Servo Alarm - X axis detect error. In the diagnostic parameter 200,
the HCA bit (bit #4) is 1 - which is abnormal current Alarm. The LED on
Servo glows with 9 (but it seem for HC it should be 8). Everything else does not have problem. The alarm comes only when there is actual cutting going on. Some time it comes soon after the cutting starts, some times it takes much longer. Spindle load is only around 50%. But if the program is run dry (just increasing the height so that there is no cutting), there is no problem. Once the alarm comes, it goes off (only) when the machine power is switched off completely. I also tried changing cutting direction. It does not have any effect.

What can be the problem?

Thanks,

Shrirang

[MysticMonkey]

first thing to do is a coil insulation check on the motor windings.

then swap the servo amplifier with one of the other amplifiers.

if the alarm follows the amp then that is the fault.

if it doesn't then change the motor encoder.