Spindle speed changes abnormally due to load.
Confirm the following
Check whether spindle speed is constant by view
of the speed meter on CRT.
Is a heavy cutting being per-
formed ? Confirm spindle load
Reduce cutting condition
Doesn’t the cutting tool worn ?
Spindle servo unit is faulty
Spindle motor is faulty
PRM 4911 : A ratio of spindle speed at which actual spindle speed is
regarded as arrived at a command spindle speed.
PRM 4912 : Spindle speed fluctuation ratio up to which the spindle
speed fluctuation detection alarm is not issued.
PRM 4913 : Spindle speed fluctuation that is not regarded as the spindle
speed fluctuation alarm.
PRM 4914 : Time when a spindle speed changed to when spindle speed
fluctuation detection is started.