SV0419 Spindle Position Error (Rigid Tap) fault in Fanuc drive

SV0419 Spindle Position Error (Rigid Tap) fault in Fanuc drive

Description

SV0419 is a specific servo alarm that occurs during Rigid Tapping. During tapping, the Z-axis servo is electronically geared to the Spindle. The servo must follow the spindle's exact rotation to cut the thread pitch. SV0419 triggers if the "Following Error" between the Spindle (Master) and the Z-axis (Slave) becomes too large. The Z-axis is effectively saying, "The spindle is spinning, and I can't keep up with the thread pitch."

Cause

• Spindle Encoder: The position feedback from the spindle is erratic or noisy.
• Servo Tuning: The gain settings for the Z-axis are too "soft," causing it to lag.
• Mechanical Bind: The tap is dull or the hole is packed with chips, causing physical drag on the Z-axis that the motor cannot overcome instantly.
• Spindle Belt: A loose spindle belt causes the motor to spin faster than the tool, confusing the sync logic.

Solution

1. Check Belts: Rigid tapping requires zero slip. Tighten spindle belts.
2. Check Tap: Use a fresh tap and proper coolant.
3. Adjust Gains: (Advanced) You may need to adjust the position loop gain of the Z-axis or the feed-forward coefficient to make the Z-axis more responsive.
4. Check Sensor: Verify the gap on the spindle magnetic sensor.