Why does bearing overload occur and how can it be prevented?

Bearings, as a key component of mechanical equipment, play the role of bearing and supporting to ensure the smooth and efficient operation of the equipment under various load conditions. Whether in a motor or a gearbox, bearings must be able to withstand the radial and axial loads generated during operation. However, when the actual load of the bearing exceeds its design limit, an overload phenomenon will occur. Overload will not only lead to the premature failure of the bearing, but may also cause more serious equipment failures.

What is bearing overload?

Bearing overload refers to the situation that the load borne by the bearing during use exceeds its rated load-carrying capacity. The rated load is usually a theoretical calculation value based on standard conditions by the bearing manufacturer, and improper use in actual work, such as excessive load, sudden impact, etc., will all lead to overload. Overload may occur during the long-term operation of the equipment, or it may occur instantaneously under sudden impact loads.

The hazards of bearing overload
According to material standards such as ISO 281 and ISO 15243, bearing overload can cause the following several common hazards to equipment:

1.Accelerated fatigue damage
When the bearing operates under overload conditions, the stress at the contact point between the rolling elements and the raceway increases significantly. Long-term overload operation will lead to material fatigue of the bearing, microcracks will appear, and eventually surface spalling or fragmentation will occur. This fatigue failure is often one of the main reasons for bearing failure.

2.Increased deformation and wear
Overload will cause excessive extrusion of the bearing raceway and rolling elements, resulting in plastic deformation. This will not only increase the friction of the bearing, but also aggravate the wear of the rolling surface. As wear increases, the operating accuracy and efficiency of the bearing will gradually decline.

3.Temperature rise
When the bearing is overloaded, due to the increase in friction, the heat generated inside the bearing also increases. The increase in temperature will not only accelerate the deterioration of the lubricant, but also cause the performance of the bearing material to decline, further increasing the risk of damage.

4.Instantaneous damage of impact load
Sudden impact loads, especially in situations such as startup or emergency braking, will cause the bearing to bear stress exceeding the design limit in a short period of time. This stress accumulation may cause local cracks in the rolling elements or raceways and even lead to instantaneous failure of the bearing.

Reasons for bearing overload
The reasons for bearing overload are often related to the equipment's usage conditions, unreasonable design, or improper maintenance.

The following are several common causes of overload:

1.Improper equipment design
When designing the equipment, the actual working conditions are not fully considered, and the bearing selection is insufficient. As a result, under heavy load, high speed, or complex load conditions, the bearing cannot withstand excessive stress.

2.Excessive radial and axial loads
In motors or gearboxes, if the radial or axial load borne by the equipment during operation exceeds the rated load of the bearing, the bearing will be in an overloaded state for a long time, leading to its premature damage.

3.Frequent starts and stops
When the equipment is frequently started, stopped or accelerated, instantaneous high impact loads will be generated. The bearing will bear relatively large stress in a short time, which is easy to cause local overload.

4.Inappropriate lubrication
Insufficient lubrication will increase the internal friction of the bearing, causing the bearing to bear greater frictional stress during operation and accelerating overload damage.

5.Misalignment
Poor alignment during equipment installation, especially poor shaft alignment between the motor and the gearbox, will cause the bearing to bear additional eccentric loads. This uneven load will lead to local overload of the bearing.

How can bearing overload be avoided?
To avoid bearing overload, equipment operators and maintenance engineers need to take measures from multiple aspects of design, operation and maintenance:

1.Reasonable bearing selection
At the design stage, bearings must be reasonably selected according to the actual working conditions and load conditions to ensure that their rated loads can meet the long-term operation requirements of the equipment. If the working conditions are complex, bearings with higher rated loads or special bearings can be selected.

2.Control equipment load
Avoid long-term overload operation of the equipment. Especially in equipment such as motors and gearboxes, ensure that the load is within the rated load range of the bearing. For working conditions that may cause instantaneous overload, it is recommended to design appropriate overload protection measures.

3.Optimize start and stop operations
Reduce the frequency of frequent starts and stops of the equipment, or use a soft start device to avoid damage to the bearing from impact loads. Soft start technology can reduce the impact stress during startup and reduce the risk of bearing overload.

4.Ensure correct lubrication
Regularly check the lubrication condition of the bearing, ensure that the lubricant is replenished on time, and select lubricating oil or grease suitable for the working temperature and load. Lubrication can effectively reduce friction and reduce the temperature rise and wear of the bearing under heavy load conditions.

5.Precise alignment and installation
During the equipment installation process, ensure the shaft alignment accuracy of the motor and gearbox. Through alignment tools and laser alignment instruments, ensure that the load borne by the bearing is evenly distributed and avoid local overload.

Bearing overload is one of the main reasons for bearing failure and will have a profound negative impact on the normal operation of equipment. Through reasonable design, load control, optimized operation, good lubrication management and installation alignment, the occurrence of bearing overload can be effectively avoided and the service life of bearings and equipment can be prolonged. In daily use, regular inspection and maintenance to ensure that the equipment operates within a safe load range can significantly improve the operating efficiency and reliability of the equipment.