Troubleshooting Common Problems in Permanent Magnet Stepper Motors: Tips and Solutions

Here are tips and solutions for troubleshooting common problems in permanent magnet stepper motors:

1. Motor Doesn’t Rotate

Power Failure: Check for power failure, driver failure, or motor damage.
Connections: Check the wiring connections between the stepper motor, driver, and controller, ensuring they are tight and accurate. Discoloration at terminals may indicate a loose connection.
Wiring Issues: If wires were lengthened, check the connection between the standard leads and the added length.
Driver Parameters: Adjust driver parameters regularly, such as current and subdivision. Follow the driver’s instructions to avoid motor damage. Ensure that the driving circuit parameters match the motor’s requirements.
Motor Damage: Check for motor damage or connection problems.
Stuck Motor: Too much environmental dust can cause the motor to get stuck.
Rusted Components: If poorly stored, the surface of the stator and rotor may have rusted and stuck.
Scratched Components: The motor bundle may be assembled, and the stator and rotor scratched.

2. Motor Speed is Unstable

3. Motor is Overheating

Overload: Reduce the load on the motor. Ensure that the load of the motor is within its tolerance range.
Heat Dissipation: Improve heat dissipation. The ambient temperature may be too high, or the heat dissipation condition is poor.
Motor Failure: Check for motor or driver failure.
Driver Issues: When the drive circuit fails, the motor may work in a single high voltage or in a high-frequency state for a long time, and the temperature rise of the motor may also become higher. For a driving circuit of high and low voltage power supply working at high frequency, the high voltage pulse width should not be too wide and should be adjusted according to the technical standard; otherwise, the temperature rise will be high.

4. Excessive Noise and Vibration

Gear Clearance: There may be excessive clearance of transmission gear.
Inertial Load: Pure inertial load with frequent positive and reverse motions.
Axial Clearance: There may be excessive axial clearance.
Resonance Zone: The motor may be operating in the resonant frequency range.
Damper: The damper may not be properly adjusted or may have failed.
Loose Connections: A loose wire can cause excessive noise and vibration.
Long Cables/Small Gauge Wires: Check whether the wires/cables are too long, or if the motor’s lead wires are of a gauge too small.

5. Motor Stalling

Voltage Spike: Stalling of a stepper motor can cause a large voltage spike that damages the phase transistors on the driver.
Transient Suppression Devices: Transient Suppression Devices can be added externally.
Load: Too much environmental dust may be sucked in by the motor.
Parameters and Standards: The working mode may not be in accordance with the prescribed standards.
Loose Components: The rotor core and motor shaft may be too loose.
Wiring: Incorrect wiring.

6. Poor System Performance

EMI Problems: Check for EMI problems. Use shielded cables for stepper motor wiring whenever possible.
Skipping Steps: Check for motor skipping steps intermittently or low repeatability.
Erratic Behavior: Check for erratic behavior of the motor – run forward, run in one direction then the other.
Wires Heating Up: Check for wires heating up or possibly melting.
Age of Motor: With time and use, stepper motors lose a portion of their magnetism, which affects performance. One can typically expect 10,000 operating hours for stepper motors (approximately 4.8 years, running one eight-hour shift per work day) or as many as 20,000 operating hours, assuming high-quality components and ideal operating conditions1.

7. General Maintenance

Cleaning: Regularly clean the dust and dirt on the surface of the motor with a clean soft cloth. Avoid using wet cloth or chemical solvents.
Lubrication: For permanent magnet stepper motors with bearings, regularly check the lubrication of the bearings. If lubrication is insufficient, add an appropriate amount of lubricating oil or grease in time. Be careful to choose lubricants suitable for motors and add them according to the prescribed time and method.
Storage: If the motor needs to be stored for a long time, store it in a dry, ventilated, non-corrosive gas environment. Avoid direct sunlight and moisture. When carrying the motor, handle it with care to avoid collision and vibration.

8. Testing Motor Windings

The motor windings can be tested with an ohmmeter.
Disconnect the motor from the load and driver, then try to rotate the shaft by hand. However, make sure that the lead wires are not touching each other, as it will “lock” the phases and prevent motor rotation. If the shaft rotates without any issues or if you don’t feel excessive friction, then the ball bearing is good; otherwise, replace the motor.

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