231-8640

Check axis movement manually

Use Manual Operation mode to jog the affected axis at low feedrate (10-50 mm/min) and feel for binding, roughness, or excessive resistance.

Ensure machine is properly homed and all safety systems are active before manual movement

Inspect mechanical components

Check ballscrews, linear guides, and coupling for damage, contamination, or improper lubrication. Verify proper backlash compensation settings in MP1410-MP1419.

Listen for unusual noises during movement - grinding or clicking often indicates mechanical issues

Verify cutting parameters

Review programmed feedrates and spindle speeds in the NC program. Check if recent program changes increased cutting forces beyond motor capability.

Compare current I²T values in the servo diagnostics screen against historical data if available

Access servo parameter diagnostics

Navigate to Setup → Machine Parameters → Servo and check MP1020 (max current), MP1021 (continuous current), and current I²T threshold values against motor specifications.

Document original values before making any changes

Check position loop gains

Review MP1300 (position gain), MP1310 (velocity gain), and MP1312 (acceleration feedforward) for proper tuning. Excessive gains cause servo hunting and high current draw.

Incorrect servo tuning can cause dangerous machine oscillations

Perform servo optimization

Use TNC's automatic servo optimization function in Setup → Servo Optimization if available, or restore known good parameter backup from Setup → General → Backup/Restore.

Run optimization with typical workpiece load for best results

Check encoder diagnostics

Access Setup → Diagnostics → Encoder and verify encoder signals are clean with proper amplitude. Look for error counters or signal quality warnings.

Encoder problems often show as intermittent position errors before causing I²T alarms

Verify motor connections

Inspect motor power and encoder cable connections for looseness, corrosion, or damage. Check cable routing for interference from power cables or welding equipment.

Always disconnect power before checking electrical connections

Test motor insulation

Use megohmmeter to test motor winding insulation resistance. Values below 1 megohm typically indicate motor winding problems requiring motor replacement.

Disconnect motor cables from drive before insulation testing to prevent drive damage

Check motor temperature readings

Navigate to Setup → Diagnostics → Servo Status and verify actual motor temperature readings are reasonable (typically 20-80°C depending on ambient and load).

Compare temperature readings with infrared thermometer measurements on motor housing

Verify thermal parameters

Check MP1025 (thermal time constant), MP1026 (thermal monitoring), and MP1027 (temperature limit) match motor manufacturer specifications exactly.

Heidenhain motors typically have thermal time constants between 15-45 minutes

Reset I²T accumulator

After verifying motor is cool, reset the I²T accumulator through Setup → Servo → Reset Thermal Model or by cycling servo drive power with proper shutdown procedure.

Only reset thermal protection after confirming motor has cooled to ambient temperature