Bearing Failure Analysis

Asks three important questions

1. What failed? 2. Why did it fail? 3. How can the failure be prevented from happening again?

10 Common Causes of Bearing Failure

Improper Lubrication

Use the lubricant recommended for the bearing and application. Check load, speed, operating temperature, environment and lubricant compatibility before selecting grease or oil.

Contamination

Keep bearings in their original packaging until installation. Use clean tools, clean hands and clean work areas. Inspect seals regularly and prevent water or process contaminants from entering the bearing.

Incorrect Installation

Inspect the shaft. Inspect the housing. Check dimensional tolerances. Clean mating surfaces. Use the correct mounting tool. Apply force only to the appropriate ring. Verify alignment and seating. Check rotation after installation.

Shaft/Housing Misalignment

Check shaft straightness, housing geometry and mounting alignment. For critical machinery, use appropriate alignment and condition-monitoring methods rather than relying only on visual inspection.

Overloading

Calculate the actual radial, axial and combined loads before selecting a bearing. Consider shock loads, acceleration, moment loads and operating conditions rather than using only the nominal machine load.

Excessive Speed

Check the manufacturer's recommended speed limits and select the lubricant and bearing configuration according to the actual operating speed.

Excessive Vibration

Establish a baseline vibration level for healthy equipment and monitor changes over time. A sudden or progressive increase should trigger investigation rather than simply waiting for the bearing to fail.

Corrosion & Moisture

Use appropriate seals and corrosion protection. Protect bearings during storage and prevent moisture from entering the housing.

Electrical Bearing Damage

For motor applications, evaluate the electrical system and bearing arrangement. Depending on the application, solutions may include appropriate insulation, grounding arrangements, electrically insulated bearings or ceramic rolling elements.

Poor Operating Conditions & Incorrect Bearing Selection

Incorrect internal clearance can also create problems. Clearance that is too small can contribute to heat generation and preload-related problems, while excessive clearance can affect running accuracy and load distribution.

A bearing showing abnormal noise, vibration or temperature should not be ignored. These can be early warning signs of developing damage. Regular inspection and condition monitoring can help identify problems before they become expensive equipment failures.

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