What causes Heidenhain alarm 231-4220?

Continuous high-load axis operation without sufficient thermal recovery time. Servo motor cooling fan failure — motor not dissipating heat during operation. Mechanical axis binding from worn bearings, tight ways, or ballscrew preload causing above-rated current. Ambient temperature in machine enclosure above rated limit for the servo motor. Motor thermistor or temperature sensor fault giving a false high reading. Servo drive current limits set too high, allowing sustained overcurrent heating.

How do I fix Heidenhain alarm 231-4220?

1. Allow the motor to cool for at least 30 minutes before clearing the alarm. 2. Inspect the motor for abnormal heat — feel the motor housing carefully and check for burning smell. 3. Check that the motor cooling fan is operating if the motor has a dedicated fan. 4. Manually move the axis with servo power off to check for mechanical binding or excessive resistance. 5. Monitor servo load percentage during a light-duty cycle after cooldown. 6. Check the motor thermistor resistance if the alarm occurs on a cold machine, which indicates a sensor fault.

Heidenhain codes

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Heidenhain Controller

Overheat/Thermal · Intermediate · 30-90 minutes

Alarm 231-4220

Heidenhain 231-4220 - Motor Temperature Exceeded in Axis

The servo motor temperature sensor for the specified axis has exceeded the maximum allowable limit. The Heidenhain control has halted axis motion to prevent motor winding insulation damage from sustained overheating.

HeidenhainOverheat/ThermalIntermediate30-90 minutes

231-4220

Heidenhain 231-4220 - Motor Temperature Exceeded in Axis

Motor temperature exceeded in axis

Safety

Allow motor to cool fully before handling — motor surface may be hot enough to cause burns

Common Causes

Continuous high-load axis operation without sufficient thermal recovery time
Servo motor cooling fan failure — motor not dissipating heat during operation
Mechanical axis binding from worn bearings, tight ways, or ballscrew preload causing above-rated current
Ambient temperature in machine enclosure above rated limit for the servo motor
Motor thermistor or temperature sensor fault giving a false high reading
Servo drive current limits set too high, allowing sustained overcurrent heating

Troubleshooting Steps

1Allow the motor to cool for at least 30 minutes before clearing the alarm.
2Inspect the motor for abnormal heat — feel the motor housing carefully and check for burning smell.
3Check that the motor cooling fan is operating if the motor has a dedicated fan.
4Manually move the axis with servo power off to check for mechanical binding or excessive resistance.
5Monitor servo load percentage during a light-duty cycle after cooldown.
6Check the motor thermistor resistance if the alarm occurs on a cold machine, which indicates a sensor fault.

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Always verify with your machine manual or a certified technician before performing service procedures.