How to avoid early failure of bearings: systematic analysis and preventive strategies

Bearings are the core components of almost all rotating machinery, and their reliability directly affects the operating status, production efficiency, and maintenance costs of the entire equipment. According to statistics, more than half of the bearing failures did not reach their calculated fatigue life, but were caused by various avoidable reasons leading to early failures. Avoiding early failure is not a matter of luck, but a systematic project that involves every step from selection, installation, use to maintenance.
This article will delve into the fundamental causes of early bearing failure and provide a comprehensive and actionable prevention strategy.
####1. Identify common patterns and root causes of early failures**
To avoid failure, one must first recognize failure. Early failure of bearings is usually manifested by abnormal noise, high temperature rise, and intensified vibration. Its physical form and root causes mainly include:
1. Lubrication Failure: The most common cause of early failure, accounting for over 50%. **
-Insufficient lubrication: Insufficient oil film or grease can completely separate the raceway from the rolling elements, resulting in direct contact between the metal and causing severe friction, high temperature, and adhesive wear (bonding).
-Lubricant selection error: Improper viscosity, lubricant type (oil/grease) does not match working conditions (speed, load, temperature).
-Lubricant contamination or aging: Impurities mixed into the lubricant or failure due to high-temperature oxidation.
2. Pollution: The "number one killer" of bearings. **
-Hard particles such as dust, metal shavings, and sand particles invade the interior of bearings and become stress concentration points, causing indentation and abrasive wear on the raceway, resulting in vibration and noise, and rapidly shortening the service life.
3. Improper Installation:
-Violent installation: Using a hammer to directly strike the bearing can cause * * Spalling * * of the ring raceway or rolling elements.
-Uneven force: The installation force was not applied to the correct ring (the force hit the outer ring when installing the inner ring), resulting in damage to the raceway.
-Misalignment: After the installation of the bearing, the center lines of the inner and outer rings do not coincide, resulting in additional bending moments that cause the rolling elements to "climb" on the raceway, leading to biased loads and early fatigue.
4. Improper Fitting:
-* * Tight fit: * * Resulting in complete elimination of bearing clearance or even preloading, increased temperature rise, fatigue of the inner ring due to tensile stress, and difficulty in assembly and disassembly.
-Loose fit: This can cause creep (micro motion wear) between the mating parts, wear the shaft or bearing seat, and cause vibration and looseness.
5. * * Fatigue * *:
-Although fatigue is a normal failure mode of bearings, if fatigue occurs before reaching the rated life, it is usually caused by the above reasons (such as pollution, improper installation) leading to stress concentration on the subsurface.
####2. Systematic Prevention Strategy: Full Lifecycle Management from Design to Maintenance**
To avoid early failure, a closed-loop management system is required. The following figure clearly illustrates the core steps and decision-making path for the full lifecycle health management of bearings:
```mermaid
flowchart TD
A [Whole life cycle health management of bearings] -->B
    
Subgraph B [Phase 1: Design Selection and Preparation]
B1 [Correct selection<br>Calculate load and life]
B2 [Choose appropriate<br>fit and clearance]
B3 [Select matching lubricant]
B4 [Check bearing condition<br>Clean working environment]
end
B --> C
Subgraph C [Phase 2: Precise Installation and Debugging]
C1 [Use professional tools<br>(hydraulic nuts, induction heaters, etc.)]
C2 [Follow the correct installation method<br>Ensure neutrality]
end
C --> D
Subgraph D [Phase 3: Operation, Maintenance, and Monitoring]
D1 [Maintain lubrication, cleanliness, and adequacy<br>Perform regular maintenance]
D2 [Status Monitoring<br>(Listening to Noise, Measuring Vibration, Checking Temperature)]
end
D -->E {Did you find any abnormalities? }
E -- No -->D
E -- Yes -->F [Stop immediately for troubleshooting]
F -->G [Root Cause Analysis (RCA)<br>and replace components]
G --> C
```
**1. Correct design and selection (design phase)**
-Accurate calculation: Calculate the required bearing rated dynamic load and service life based on actual working conditions (load, speed, temperature), and select the appropriate bearing type and size. Do not "magnify" the selection based on experience, as oversized bearings may cause other problems.
-* * Consider all factors: * * In addition to the basic load, it is also necessary to consider the impact load, materials of the shaft and bearing seat, and their thermal expansion characteristics (see the article "Analysis of Thermal Expansion Characteristics of Bearings"), and choose the appropriate * * initial clearance * * and * * fit tolerance * *.
**2. Fine installation and debugging (installation phase)**
-* * Use the correct tools: * * Resolutely eliminate violent installation. Be sure to use specialized tools such as * * special sleeves * *, * * hydraulic nuts * *, or * * induction heaters * * (to evenly heat the bearing inner race for hot installation) to ensure that the installation force is evenly and vertically applied to the end face of the interference fit ring.
-* * Ensure Neutrality: * * After installation, use a dial gauge to check the alignment of the shaft and bearing seat to ensure that it is within the allowable error range.
-Initial lubrication: Before installation, ensure that the bearings are clean and add an appropriate amount of initial grease as needed. For the oil lubrication system, ensure that the oil circuit is unobstructed before starting.
**3. Scientific lubrication management (operational phase)**
-* * Choose the right lubricant: * * Select the appropriate type and viscosity of lubricant based on speed (DN value), load, and operating temperature. Choose low viscosity oil for high-speed light load and high viscosity oil or grease for low-speed heavy load.
-Control lubrication amount: The more, the better. Excessive lubrication, especially grease, can lead to excessive stirring heat, which in turn causes the bearing temperature to rise. The manufacturer's recommended filling amount should be followed.
-Maintain lubrication cleanliness: Regularly check the cleanliness of lubricants and replace or replenish them on time. The oil lubrication system should be equipped with efficient filtering devices. In polluted environments, bearings with good sealing effects and effective sealing devices should be selected.
**4. Effective state monitoring and maintenance (maintenance phase)**
-Listen: Monitor whether there are any abnormal sharp noises, impact sounds, or roaring sounds during operation.
-* * Touch/Measure: * * Regularly check the temperature of the bearing seat, abnormal temperature rise is often an early signal of malfunction.
-* * Testing: * * Use a vibration analyzer to regularly detect the vibration signal of the bearing. Vibration spectrum analysis is one of the most effective methods for diagnosing early damage to bearings, such as peeling and pitting.
-Establish a preventive maintenance (PM) plan: Based on the importance and operating conditions of the equipment, develop a plan for regular inspections, cleaning, oil changes, and bearing replacements.
####III. Conclusion**
Avoiding early failure of bearings is not a single point issue, but a systematic engineering process that spans the entire lifecycle of the equipment. It requires engineers and technicians to have systematic knowledge, infer design specifications from failure modes, execute installation processes with a refined attitude, and use preventive thinking for operation and maintenance.
By implementing the above strategies, it is possible to eliminate avoidable errors to the greatest extent possible, allowing bearings to achieve their expected design lifespan, significantly reducing equipment downtime, and improving production efficiency and economic benefits. Remember, the vast majority of premature deaths in bearings are caused by human factors, and scientific management is the most effective way to maintain their health.