FANUC Series 16/18/160/180-Model C Machining Center Operators Manual

When high–speed chopping is performed with the grinding axis, a servo
delay and acceleration/deceleration delay occur. These delays prevent the
tool from actually reaching the specified position. The control unit
measures the difference between the specified position and the actual tool
position, and automatically compensates for the displacement of the tool.
To compensate for this displacement, an amount of travel equal to the
distance between the upper and lower dead points, plus an appropriate
compensation amount, is specified. When a chopping command is
specified, the feedrate is determined so that the chopping count per unit
time equals the specified count. When the difference between the
displacement of the tool from the upper dead point and the displacement
of the tool from the lower dead point becomes smaller than the setting of
parameter No. 8377, after the start of chopping, the control unit performs
When compensation is applied, the chopping axis moves beyond the
specified upper dead point and lower dead point, and the chopping
feedrate increases gradually.
When the difference between the actual machine position and the
specified position becomes smaller than the effective area setting
(parameter No. 1826), the control unit no longer applies compensation,
allowing the tool to continue moving at its current feedrate.
A coefficient for the compensation amount for the displacement
generated by the servo delay incurred by chopping and the delay incurred
during acceleration/deceleration can be specified in parameter No. 8376.
Point R
Upper dead point
L2 L4 L6
L3 L5
Lower dead point
Displacement between the tool and the upper dead point: L2, L4, L6
Displacement between the tool and the lower dead point: L1, L3, L5
Compensation starts when:
| L3 – L2 | < (parameter No. 8377)
When the following condition is satisfied, compensation is no longer applied,
and the tool continues to move at its current feedrate:
| L6 | < effective area setting (parameter No. 1826)
D Servo delay
compensation function

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