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Check DIAGNOSIS screen > Spindle > Spindle Load Meter. Navigate SYSTEM > DIAGNOSIS > [Spindle] and observe parameter 4131 (spindle load). Values consistently above 80-90% indicate overload conditions.

Inspect spindle 3 for mechanical binding. Manually rotate the spindle in JOG mode at low RPM (M03 S100) and listen for grinding, unusual noise, or resistance. Check tool holder, drawbar operation, and bearing condition.

Ensure all workpieces and tooling are clear before manual rotation to prevent injury.

Review program around alarm occurrence for excessive feed rates or depth of cut. Check for G-code errors causing rapid engagement or collision. Reduce cutting parameters if necessary.

Verify spindle torque limit parameter 4134#3 (spindle 3 torque limit). Navigate SYSTEM > PARAM > [Spindle Parameters] and confirm parameter 4134 is set appropriately (typically 80-120% depending on application). If set too low, increase incrementally by 10%.

Check spindle amplifier LED indicators. On Alpha/Beta spindles, LED codes 4 (overcurrent) or 5 (overload) confirm torque fault. Record LED pattern and cross-reference with amplifier manual for spindle module 3.

Verify spindle motor parameters match amplifier settings. Check parameters 4001-4030 (spindle 3 motor constants): 4001 (motor type), 4002 (max speed), 4003 (base speed), 4004 (max torque). Ensure values match motor nameplate data exactly.

Incorrect motor parameters can cause catastrophic spindle failure or fire hazard.

Test spindle encoder feedback. Navigate DIAGNOSIS > Spindle > Position and observe spindle position counter during manual rotation. Erratic or frozen counts indicate encoder or cable failure requiring replacement.

Measure motor winding resistance phase-to-phase (U-V, V-W, W-U) with power OFF and amplifier disconnected. Imbalance greater than 5% or reading below 0.5 ohms indicates shorted windings requiring motor replacement.

Lockout/tagout all power sources and discharge amplifier capacitors (wait 5 minutes) before measurement.

Review parameter 4134 bits for spindle 3 torque alarm enable and threshold. Bit 3 enables torque limit, parameter 4135 sets percentage (0-255 = 0-255%). Confirm 4135 is not set below 80 unless specifically required.

Check parameter 4138 (spindle 3 overload detection time). Default is 1000ms. If set too short (<500ms), transient loads trigger false alarms. Increase to 1500-2000ms for applications with shock loads.

Verify parameter 3736#3 (spindle load detection method). Bit 0=OFF uses current detection, bit 0=ON uses torque command. Ensure setting matches amplifier type and application requirements per Fanuc Spindle Parameter Manual.

Reset alarm and perform test cut at reduced spindle load (50% feedrate, 70% spindle speed). Monitor DIAGNOSIS > Spindle Load during operation. If alarm does not recur, gradually increase parameters while monitoring until optimal settings achieved.