SV0422 Torque Control Excess Speed fault in Fanuc drive

SV0422 Torque Control Excess Speed fault in Fanuc drive

Description

SV0422 is a specific alarm for applications using "Torque Control Mode" (e.g., servo pressing, tensioning, or tailstocks). In this mode, the CNC commands a specific Force (Torque), not a specific position. The motor is supposed to push against the workpiece. However, if the workpiece is missing or slips, the motor—trying to maintain torque—will accelerate rapidly because there is no resistance. SV0422 trips if the speed exceeds the safety limit while in torque mode.

Cause

• Missing Part: The tailstock advanced to hold the part, but the part wasn't there. The quill shot forward at max speed.
• Belt Break: The motor is applying torque to a belt, the belt snaps, and the motor freewheels.
• Parameter: The "Speed Limit in Torque Control" parameter is set too low.

Solution

1. Check Workpiece: Ensure the part is clamped correctly before the torque cycle begins.
2. Adjust Speed Limit: Check parameter 2017 (or similar depending on series) to increase the allowable speed ceiling during torque operations.
3. Check Coupling: Ensure the motor is physically connected to the load.