Fault Analysis and Troubleshooting Methods for Motor Bearings

1. The retainer makes a “shri-shri…” sound.

Cause analysis: This phenomenon is caused by vibration and impact between the retainer and rolling elements. It can occur regardless of the type of grease used, and is more likely to happen when the bearing is subjected to high torque, heavy loads, or large radial clearance.

Solution:

1. Improve the precision of the retainer;

2. Select bearings with small clearance or apply preload to the bearings;

3. Reduce torque load and minimize installation errors;

4. Choose high-quality oils and fats.

II. Continuous buzzing sound: “Buzz….”

Cause analysis: When the motor runs without load, it emits a buzzing-like sound and experiences abnormal axial vibration. Additionally, there is a humming sound when the motor is turned on or off.

Specific characteristics: This phenomenon frequently occurs in motors with poor lubrication, particularly during winter and when ball bearings are used at both ends. It is primarily an unstable vibration that arises under the influence of axial vibration, especially when the shaft’s self-aligning capability is inadequate.

Solution:

1. Use lubricants with excellent lubrication performance;

2. Apply preload to reduce installation errors;

3. Select bearings with small radial clearance;

4. Increase the rigidity of the motor bearing housing;

5. Enhance the self-aligning capability of the bearing.

Note: The fifth point plays a fundamental role in improvement, employing a 02 small-groove curvature and a 01 large-groove curvature.

III. Lacquer Rust

Cause analysis: After the motor bearing housing was painted and the paint dried, volatile chemical components corroded the end faces, outer raceways, and raceway grooves of the bearing, resulting in abnormal noises caused by corrosion of the raceway grooves.

Specific feature: After corrosion, the bearing surface exhibits more severe rusting than the first surface.

Solution:

1. Assemble the rotor and casing after they have been dried or oven-dried.

2. Reduce motor temperature;

3. Select a model that is compatible with the paint;

4. Improve the ambient temperature where the motor bearings are located;

5. Use appropriate lubricants—greases cause less rust, while silicone oils and mineral oils are most likely to induce rust.

6. Vacuum impregnation process is adopted.

IV. Impurity Sounds

Cause analysis: The abnormal sound, which is irregular and unusual, is caused by the cleanliness of the bearings or lubricant. Specific characteristics: The sound occurs intermittently—sometimes present, sometimes absent—and varies in intensity without any regular pattern. It is more commonly observed in high-speed motors.

Solution:

1. Use high-quality oils and fats;

2. Improve cleanliness before grease injection;

3. Enhance the sealing performance of bearings;

4. Improve the cleanliness of the installation environment.

5. High-frequency, vibrating sound: “Dada...”

Specific characteristics: The sound frequency varies with the bearing’s rotational speed, and surface waviness of the component is the primary cause of noise.

Solution:

1. Improve the surface machining quality of bearing raceways and reduce the amplitude of waviness.

2. Reduce bruising;

3. Adjust the preload and fit clearance, check the operation of the free-end bearing, and improve the precision installation method for the shaft and bearing housing.

6. Heating up

Specific issue: After the bearing starts running, the temperature exceeds the required range.

Cause Analysis:

1. Excessive grease leads to increased resistance from the lubricant;

2. Excessive internal load caused by insufficient clearance;

3. Installation error;

4. Friction of sealing equipment;

5. Bearing creep.

Solution:

1. Choose the right type of oil and use it in the proper amount.

2. Adjust the preload and fit clearance, and check the operation of the free-end bearing.

3. Improve the accuracy of the bearing housing and its installation method;

4. Improve the sealing design.

7. The bearing feels rough to the touch.

Specific characteristic: When rotating the rotor by hand while holding the bearing, you can feel impurities and resistance inside the bearing.

Cause Analysis:

1. Excessive clearance;

2. Improper fit between the inner diameter and the shaft;

3. Channel damage.

Solution:

1. The clearance should be as small as possible;

2. Selection of tolerance zones;

3. Improve accuracy and reduce damage to the channel;

4. Selection of oils and fats.