The maintenance and replacement cycle of bearings is crucial for ensuring the stable operation of equipment

In industrial production and mechanical equipment, bearings are known as the "joints of machinery". They support rotating shafts, reduce friction, and ensure smooth and efficient operation of equipment. However, bearings are also critical components that bear loads and wear, and their performance will gradually deteriorate over time. Therefore, scientifically formulating and implementing maintenance and replacement cycles for bearings is the core link in preventing unexpected shutdowns, reducing maintenance costs, and extending equipment life.

1、 The lifecycle and failure symptoms of bearings
Bearings are not permanent components, and their lifecycle typically follows a typical 'bathtub curve':

Early failure period: Due to improper installation, poor lubrication, or manufacturing defects, early failure may occur during the early stages of operation.

Accidental failure period (stable operation period): With proper installation and good maintenance, the bearing enters a long stable operation phase with a low failure rate.

Wear and tear failure period: After long-term operation, due to fatigue, wear, corrosion and other reasons, the performance of the bearing sharply decreases, and the failure rate significantly increases.

It is crucial to identify common signs of bearing failure, including:

Abnormal noise: continuous buzzing, impact sound, or piercing whistling sound.

Abnormal vibration: The vibration of the equipment increases significantly during operation, which can be detected by hand feel or instrument testing.

Excessive temperature rise: When the surface temperature of the bearing seat exceeds the normal ambient temperature by+40 ℃ (or more than 85 ℃), it is usually a signal of poor lubrication or excessive pre tightening.

Performance degradation: equipment operation accuracy decreases, energy consumption increases, and output power is insufficient.

Lubricant leakage or contamination: seal failure leading to oil leakage, or discoloration (blackening) of lubricating grease, containing a large amount of metal debris.

2、 Core factors determining maintenance and replacement cycles
The replacement cycle of bearings is not a fixed time or speed, but is determined by multiple factors:

Work load: The greater the load (especially impact load), the shorter the lifespan.

Operating speed: The higher the rotational speed, the greater the heat and centrifugal force generated, and the higher the requirements for lubrication and the bearing itself.

Working environment: Being in a dusty, humid, corrosive atmosphere or extreme temperature environment can significantly accelerate the wear and corrosion of bearings.

Installation and alignment accuracy: Improper installation and shaft misalignment can cause additional stress, which is one of the main reasons for early bearing failure.

Lubrication condition: Lubrication is the "blood" of bearings. The type, quantity, frequency of replacement, and cleanliness of lubricants directly determine the lifespan of bearings. According to statistics, over 50% of bearing failures are caused by lubrication issues.

Bearing type and quality: Bearings with different designs, precision levels, and manufacturing qualities have significant differences in their rated life (such as L10 life).

3、 Two main maintenance strategies
In actual production, two strategies are usually used to determine the timing of bearing maintenance and replacement:

Time Based Maintenance

Concept: Based on equipment operating time or output, set a fixed cycle (such as every 5000 hours of operation or every 10000 tons of product produced) for shutdown inspection, lubrication maintenance, or direct bearing replacement.

Advantages: Strong planning, easy management, and can effectively avoid sudden failures.

Disadvantage: It may cause the bearings to be over maintained (in good condition but replaced) or under maintained (damaged before the cycle).

Predictive Condition Based Maintenance

Concept: By utilizing advanced monitoring technology, the operational status of bearings can be monitored in real-time or periodically, and maintenance or replacement can be determined based on their actual health condition.

Common methods:

Vibration analysis: The most effective and commonly used method to accurately determine the type and severity of bearing damage by analyzing the vibration spectrum.

Temperature monitoring: Monitor the trend of bearing temperature changes.

Lubricating oil analysis: detecting oil viscosity and metal particle content.

Noise analysis.

Advantages: It can accurately warn before faults occur, maximize the use of bearing life, reduce unnecessary downtime and spare parts consumption.

Disadvantage: Initial investment is required to purchase monitoring equipment and train personnel.

For critical equipment, it is recommended to adopt a strategy that prioritizes predictive maintenance and supplements preventive maintenance.

4、 Best practices for bearing maintenance and replacement
When deciding to replace bearings, standardized procedures should be followed:

Preparation work: Prepare suitable spare parts, specialized tools (such as pullers, hydraulic nuts, etc.), cleaning agents, and new lubricating grease.

Disassembly: Use the correct tools to record the relative position of the bearings and related components, and check the wear of the shaft and bearing seat.

Cleaning and Inspection: Clean the old bearings, carefully inspect the wear, corrosion, and fatigue signs (such as pitting and peeling) of the raceway, rolling elements, and cage, and analyze the root cause of failure.

Installation: Hot installation or hydraulic method should be preferred to avoid direct tapping. Ensure proper installation and adjust the appropriate clearance or preload.

Lubrication: Add an appropriate amount and the correct type of fresh lubricating grease according to the manual requirements. Remember that 'more is not better', excessive lubrication can lead to excessive temperature rise.

Trial operation and verification: After installation, conduct a no-load trial operation to check for any abnormal noise, vibration, and temperature rise. Once confirmed to be normal, put it into full load operation.

Conclusion
The maintenance and replacement cycle of bearings is a technology that combines scientific calculation and empirical judgment. Abandoning the old concept of 'no damage, no replacement' and establishing a predictive maintenance system based on equipment condition monitoring is the only way to achieve modern equipment management, improve production efficiency and competitiveness. Through careful maintenance and timely replacement, this' mechanical joint 'can continuously inject vitality into the equipment, ensuring the stability and efficiency of the production line.