Electric motors rely on bearings to keep the rotor spinning smoothly and minimize friction. Even the best bearings wear out over time. Promptly replacing bearings can help avoid costly downtime and extend the life of the motor. This guide explains the causes of bearing failure, how to recognize warning signs, and a step-by-step process for safely replacing bearings.
Why Bearing Replacement is Important
Bearings support the motor shaft and maintain precise alignment. When bearings fail, the rotor can wobble or seize, leading to overheating, vibration, or permanent damage to core motor components. Preventive replacement maintains high performance and efficiency.

Common Causes of Bearing Failure

Lack of Lubrication: Dry or contaminated grease can cause excessive friction.
Overload or Misalignment: Excessive radial or axial loads can stress the bearings.
Contamination: Dust, moisture, or chemicals can pit raceways and rollers.
Galvanic Corrosion: When electrical current passes through the bearing, it causes pitting, known as galvanic erosion.
Warning Signs Bearing Replacement is Required
Unusual Noise: Grinding, humming, or squealing.
Excessive Vibration: Feeling through the housing or detected through vibration analysis. Heat buildup: The bearing housing is running hotter than normal.
Reduce motor speed or efficiency.

Preparation and Safety

Disconnect and lock out power to the motor.
Wear safety glasses and gloves.
Have the correct replacement bearing, puller, and installation tools ready.
Check the motor’s service manual for specifications and torque settings.
Replacement Procedure
Remove the motor
Disconnect the wiring and remove the motor from the bracket.
Mark the housing and end cover to ensure proper reassembly.
Remove the end cover
Remove the bolts and carefully separate the end cover from the stator.
Remove the old bearing
Use a bearing puller or hydraulic press to avoid shaft damage.
Inspect the shaft and housing for wear or scoring.
Cleaning and Inspection
Wipe all components with a lint-free cloth.
Inspect seals, gaskets, and retainers; replace if necessary.
Install the new bearing
Use a shaft press or induction heater to press the new bearing onto the shaft to create an interference fit.
Apply force only to the inner race to avoid damage.

Proper Lubrication
Use the lubricant recommended by the motor manufacturer.
Avoid overlubrication, which can cause overheating.
Reassemble and Test
Reinstall the end caps and tighten the bolts to the specified torque.
Spin the rotor by hand to confirm smooth rotation.
Run a short test at low power and monitor vibration and temperature.
Tips for Extending Bearing Life
Follow a regular lubrication schedule.
Keep the motor clean and dry.
Use high-quality sealed bearings suitable for the operating environment.
Monitor vibration and temperature to detect early problems.

Your Trusted Partner in Bearing Solutions

When it’s time for electric motor bearing replacement, DFL NSAR is ready to help.
Global Supply Chain: Fast shipping from our overseas warehouses.
Wide Product Range: From standard deep groove to advanced polymer and ceramic bearings.
Expert Support: Our engineers can guide you from selection to installation.
Contact DFL NSAR today to keep your motors running smoothly and avoid unexpected downtime.