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Movement - If the power is on and if the fan does not operate or the fan blades
cannot be moved even manually, or if the fan blades are rotating
but no cooling wind is blown out, the fan motor may have cutting
chips or sludge accumulated in it and needs to be cleaned.
- If the fan does not operate normally for any other reason, the fan
motor needs to be replaced.
- Check that forcible cooling does not cause dew condensation on
the motor surface. Dew condensation is likely particularly when the
cooling unit continues to run after the machine is stopped. In that
case, be sure to make this check.
- Dew condensation or water drop on the motor surface can reduce
the motor's service life. It is necessary to wipe it dry and take a
measure to prevent recurrence.
Forcible cooling unit
(when using an
external cooling unit
such as liquid
Liquid leakage/clog - Check the cooling pipe for leakage or clog. Do not drive the motor
unless the leakage or clog is fixed.
- Liquid leakage from a spindle motor with a through hole indicates a
failure of the coolant joint. In this case, the joint needs to be
- In the case of liquid leakage from a linear motor (coil slider), the
linear motor (coil slider) needs to be replaced.
- If the motor gets wet due to liquid leakage or any other cause, it is
necessary to clean and dry the motor and perform electric
characteristic checks (winding resistance/insulation resistance).
Insulation resistance measurement
The following table shows the judgment criteria to be applied when measuring insulation resistance between winding and frame
using a megohmmeter (500 VDC).
Insulation resistance Judgment
100 Ω or higher Acceptable
10 to 100 Ω
The winding has begun deteriorating. There is no problem with the performance at
present. Be sure to perform periodic inspection.
1 to 10 Ω
The winding has considerably deteriorated. Special care is in need. Be sure to perform
Lower than 1 Ω Unacceptable. Replace the motor.
If insulation resistance drops sharply during a short period of time or if the circuit breaker trips, the cutting fluid or other foreign
matter may have entered the inside of the motor or cable. In that case, contact the machine tool builder or FANUC for
Let the motor dry and cool to room temperature before winding or insulation resistance is measured.
Otherwise, not only an accurate measurement cannot be performed but also the motor may be damaged.
The winding or insulation resistance measurement should be performed on the motor alone, with its power
Measuring insulation resistance with the motor connected to the amplifier may damage the amplifier.
During insulation resistance measurement, applying voltage to the motor for a long time may further
deteriorate the insulation of the motor. Therefore, the measurement of insulation resistance should be
performed in a minimum amount of time where possible.
When disconnecting the power line and other cables, take an appropriate measure, such as labeling, to
ensure that they can be restored to their original state.
188.8.131.52 Periodic cleaning of a motor
Periodic cleaning is necessary to remove an accumulation of cutting chips or sludge that may eventually cause a failure. Also,
leaving the cutting fluid or other chemical substance attached for a long time can reduce the motor's service life substantially.
When forcible cooling is provided by a liquid or air cooling unit, check the unit for pipe clog, fan failure, etc. and perform
cleaning periodically to ensure that the coolant flows smoothly and that the motor is cooled properly.