420

Identify master and slave axes from synchronous control setup. Go to SYSTEM > PARAM and check parameter 1800 (axis control parameter) and parameters 2026-2030 for synchronous control configuration to confirm which axes are paired.

Enter JOG mode and manually move each axis independently. Check for binding, unusual resistance, chips in ways, damaged ballscrews, or seized bearings. Listen for abnormal noise during movement.

Ensure machine is in emergency stop ready condition when manually checking axes

Go to DIAGNOSIS screen and monitor servo load meters for both axes. Navigate to SYSTEM > DIAGNOSIS > SERVO and observe displays 300-302 (servo load current) for each axis during synchronized motion. Compare load values between master and slave.

Inspect mechanical couplings, gantry connections, or dual-drive mechanisms for misalignment, loose mounting bolts, worn drive components, or uneven lubrication. Correct any mechanical issues found before re-enabling synchronous control.

Check parameter 2031 (synchronous torque difference detection level) at SYSTEM > PARAM > SERVO. Typical values range from 20-50% depending on application. Compare current setting against machine specifications or OEM documentation.

Verify servo gain parameters match between synchronized axes. Check parameters 1825 (position loop gain), 1826 (velocity loop gain), and 1828 (velocity integral time constant) for both master and slave axes. Values should be identical for matched axes.

Monitor real-time torque commands at DIAGNOSIS > SERVO. View diagnostic numbers 200-202 (torque command) for both synchronized axes during motion. Calculate the percentage difference and compare against parameter 2031 setting.

If mechanical condition is verified good but alarm persists, incrementally increase parameter 2031 by 5-10% and retest. Document original value first. Do not exceed 80% as this may mask real mechanical problems.

Increasing parameter 2031 too high may allow dangerous mechanical conditions to go undetected

Check servo amplifier LEDs on both master and slave axis drives. Verify both show normal operation (steady green). Refer to amplifier model specific LED codes in Fanuc amplifier manual for αi, βi, or αSV series.

Review alarm history at SYSTEM > ALARM > HISTORY for related servo alarms (400-499 series) on either synchronized axis. Look for patterns of 410 (overload), 414 (overheat), or 401 (disconnection) alarms indicating amplifier or motor issues.

At DIAGNOSIS > SERVO, check diagnostic 308 (regenerative load) and 310 (motor temperature) for both axes. Significant temperature difference or elevated readings on one axis indicate motor degradation or cooling problems.

Perform servo test run using SYSTEM > PMC > I/O diag or manual pulse generator to command identical moves on each axis separately. Compare actual torque response and motor current draw. Replace amplifier or motor if one axis shows significantly different characteristics.

Ensure machine is clear of obstructions and all safety interlocks are active during test runs