Mitsubishi Electric MELSERVO-J4 series, Instruction Manual

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17 APPLICATION OF FUNCTIONS
17.5 Machine diagnosis function
Failure prediction function
• When the vibration failure prediction function is enabled, a vibration failure warning may occur if the gains of
the servo amplifier are changed. To enable the vibration failure prediction function, enable it after the gains
of the servo amplifier are adjusted.
• In the torque mode, the friction failure prediction function and the vibration failure prediction function cannot
be used.
• To create a dynamic friction threshold with the automatic threshold setting in the friction failure prediction
function, the equipment must be operated for 3 consecutive hours or more, and operated in the position or
velocity mode for a cumulative time of 90 hours or more after the servo motor total travel distance exceeds
1/2 of "Failure prediction - Servo motor total travel distance multiplication selection (x _ _ _)" in [Pr. PF34]

[Pr. PF41 Failure prediction - Servo motor total travel distance].
• To create a vibration level threshold with the automatic threshold setting in the vibration failure prediction
function, the equipment must be operated for 3 consecutive hours or more, and operated in the position or
velocity mode for a cumulative time of 90 hours or more.
• With MR Configurator2 or a controller, you can check thresholds when the friction failure prediction function
and vibration failure prediction function are used.
The failure prediction function predicts a failure of the equipment from the friction and vibration level during servo motor
operation, which are estimated by the friction vibration estimation function. In the failure prediction function, the friction failure
prediction function predicts a failure of the equipment from the estimated friction, the vibration failure prediction function
predicts a failure of the equipment from the estimated vibration level during servo motor operation, and the total travel
distance failure prediction function predicts a failure of the equipment from the servo motor total travel distance.
Friction failure prediction function
The friction failure prediction function predicts a failure of the equipment from the increase and decrease in the dynamic
friction (at rated speed) estimated by the friction estimation function. If a failure of the equipment is predicted, [AL. F7.2
Friction failure prediction warning] will occur.
In the friction failure prediction function, a threshold that triggers [AL. F7.2] can be set by the following two methods.
■ Automatic threshold setting
From the dynamic friction (at rated speed) estimated by the friction estimation function, a threshold that triggers [AL. F7.2] is
automatically calculated in the servo amplifier. With this setting, you can use the friction failure prediction function without
setting a threshold. However, after the servo motor total travel distance exceeds 1/2 of "Failure prediction - Servo motor total
travel distance multiplication selection (x _ _ _) in [Pr. PF34]

[Pr. PF41 Failure prediction - Servo motor total travel distance]",
a threshold is not set automatically until the equipment is operated continuously for 3 hours or more, and operated in the
position mode or velocity mode for a cumulative time of 90 hours or more. [AL. F7.2] does not occur until a threshold is
calculated in the servo amplifier.
■
Manual threshold setting
You can set a threshold that triggers [AL. F7.2] with "Friction failure prediction - Threshold multiplication (_ _ _ x)" in [Pr.
PF40], and with [Pr. PF42 Friction failure prediction - Average characteristic] and [Pr. PF43 Friction failure prediction -
Standard deviation]. For the manual threshold setting, if the servo motor total travel distance exceeds 1/2 of "[Pr. PF34 (x _ _
_)]

[Pr. PF41 Failure prediction - Servo motor total travel distance]", friction failure prediction will start. Thus, if the dynamic
friction threshold is known, or the equipment you use is configured the same as another piece of equipment used for
calculating the threshold with the automatic threshold setting, an initial failure or others can also be detected with the manual
threshold setting.
If you manually set a threshold again with the equipment used for setting the threshold automatically, set the value, which is
obtained by the automatic threshold setting, in [Pr. PF19 Friction failure prediction - Compensation coefficient 1] and [Pr. PF20
Friction failure prediction - Compensation coefficient 2]. Setting [Pr. PF19] and [Pr. PF20] will decrease the possibility of an
erroneous detection for failure prediction.