Mitsubishi Electric MELSERVO-J4 Series Instruction Manual page 559

The friction failure prediction function can be used with the following procedure.
■Friction failure prediction warning setting
To enable the friction failure prediction warning, set "Friction failure prediction warning selection (_ _ _ x)" in [Pr. PF34] to "_ _
_ 1 (automatic threshold setting)" or "_ _ _ 2 (manual threshold setting)".
[Pr. PF34]
0 0 0
Friction failure prediction warning selection
0: Disabled
1: Automatic threshold setting
2: Manual threshold setting
3: Threshold reset
■Setting of servo motor total travel distance for failure prediction
For the automatic threshold setting, set a servo motor total travel distance for failure prediction. It is recommended that the
servo motor total travel distance for failure prediction be set to about the same as the rated life presented by each guide
manufacturer and ball screw manufacturer. For example, for a rated life of 8  10
total travel distance multiplication selection (x _ _ _)" in [Pr. PF34] to "2 _ _ _", and set [Pr. PF41] to "80".
■Threshold setting method
For the automatic threshold setting, [Pr. PF42 Friction failure prediction - Average characteristic] and [Pr. PF43 Friction failure
prediction - Standard deviation] for determining a threshold are automatically rewritten according to the dynamic friction (at
rated speed) estimated in the servo amplifier. At this time, changing "Friction failure prediction - Threshold multiplication (_ _ _
x)" in [Pr. PF40] enables to change the threshold. If [AL. F7.2 Friction failure prediction warning] occurs with the value
obtained by the automatic threshold setting, set "_ _ _ 6" or more in [Pr. PF40 (_ _ _ x)]. After the threshold is calculated in the
servo amplifier, [Pr. PF34 (_ _ _ x)] will be set to "_ _ _ 2 (manual threshold setting)".
For the manual threshold setting, the upper and lower limit thresholds can be calculated with the equations below. When [Pr.
PF40 (_ _ _ x)] is set to "_ _ _ 0", the upper and lower limit thresholds are calculated assuming the setting as "_ _ _ 5".
Upper limit threshold [0.1%] = [Pr. PF42 Friction failure prediction - Average characteristic] + [Pr. PF43 Friction failure
prediction - Standard deviation]
 "Friction failure prediction - Threshold multiplication (_ _ _ x)" in [Pr. PF40]
Lower limit threshold [0.1%] = [Pr. PF42 Friction failure prediction - Average characteristic] - [Pr. PF43 Friction failure
prediction - Standard deviation]
 "Friction failure prediction - Threshold multiplication (_ _ _ x)" in [Pr. PF40]
5
rev, set "Failure prediction - Servo motor
17 APPLICATION OF FUNCTIONS
17.5 Machine diagnosis function
17
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