When you get an alarm on your CNC machine please note the following points to enable our service staff to quickly identify the causes. This will enable us to make your CNC machine tool repairs better.
When did the failure occur?
Note the Date and time?
Did it occur during operation? (How long was the operation?)
Did it occur when the power was turned on?
Was there any lightening surge, power failure, or other disturbances to the power supply?
How many times has it occurred?
Only once? Or occurred lots of times? (How many times per hour, per day, or per
With what operation did it occur?
What was the NC mode when the failure occurred?
Jog mode / Mem mode /Mdi /Zrn
If during program operation,
Where exactly in the program?, Which program Number, and sequence Number?
Did it occur during the axis movement?
Did it occur during the execution of an M/S/T code?
Is the Failure specific to the program?
Does the same operation cause the same failure? Check the repeatability of the failure.
Did it occur during data input/output?
(Axes and spindles)
For a failure related to feed axis servo
Occurred at both low feed rate and high feed rate?
Occurred only for a certain axis?
For a failure related to spindles
When did the failure occur? (During power–on, acceleration, deceleration, or constant rotation)
What failure occurred?
Which alarm was displayed on the alarm display screen?
(Check the axis along which an alarm has occurred for alarms 300
For alarm 350: Examine diagnostic 202
For alarm 351: Examine diagnostic 203
For alarm 414: What does diagnostic display 200,201,204
For alarm 751 or 761: Which spindle alarm is indicated?
Is the screen correct?
If machining dimensions are incorrect
a) How large is the error?
b) Is the position display on the CRT correct?
c) Are the offsets correct?
d) Other information
Is there noise source near the machine?
If the failure has not occurred frequently, the cause may be external electrical
Noise to the power supply or inductive noise on machinery cables.
Operate other machines connected to the same power line and see
If electrical noise come from the relays or compressors.
Does the machine have any countermeasure for electrical noise (i.e.: emi filter)?
Check the following for the input power supply voltage:
a) Is there variation in the voltage?
b) Are the voltages different depending on the phase?
c) Is the standard voltage supplied?
How high is the ambient temperature of the control unit?
(0 to 45 degrees Celsius during operation)
Has excessive vibration been applied to the control unit?
When you contact our service centre, specify the following items:
a) Name of the NC unit
b) Name of the machine tool builder and type of machine
c) Software series/version of the NC
d) Specifications of the servo amplifier and motor (for a failure related to the servo)
e) Specifications of the spindle amplifier and spindle motor (for a failure related to a spindle)