What faults are prone to occur when the bearing clearance is too large?

Nov 22, 2024

Bearing clearance refers to the relative movement between the inner ring and the outer ring of the bearing when it is not installed on the shaft or in the bearing seat. The radial displacement is called radial clearance, and the axial displacement is called axial clearance. The size of the bearing clearance has an important influence on the working performance and life of the bearing. When the bearing clearance is too large, a series of faults will occur. The following is a detailed analysis.

1. Reasons for excessive bearing clearance

Excessive bearing clearance may be caused by a variety of reasons, mainly including manufacturing errors, improper installation, clearance loss and excessive load.

Manufacturing error: During the bearing manufacturing process, factors such as equipment damage or improper operation may cause precision errors, resulting in excessive bearing clearance.

Improper installation: When the bearing is installed, if the fastening nut or the bearing seat needs to be installed in place, the bearing clearance will be too large.

Clearance loss: Due to long-term use or improper maintenance, the internal friction of the bearing increases, which may cause clearance loss, and then cause excessive bearing clearance.

Excessive load: Excessive load on the bearing can easily lead to excessive bearing clearance because excessive load may cause deformation of the inner and outer rings of the bearing, thereby increasing the clearance.

2. Faults caused by excessive bearing clearance

Excessive bearing clearance has a significant impact on the rotation accuracy, vibration, noise, life, etc., of the bearing. The following are possible faults when the bearing clearance is too large:

Reduced bearing life

When the bearing clearance is too large, the number of rolling elements that bear the load at the same time will decrease, which will cause the elastic deformation of the rolling elements and rings to increase. This deformation will not only reduce the rotation accuracy of the bearing, but also accelerate the wear of the bearing, thereby reducing the service life of the bearing.

Increased vibration and noise

When the bearing clearance is too large, the bearing will generate greater vibration and noise during operation. It is because the excessive clearance causes the rolling element to have unstable contact with the inner and outer rings during rolling, resulting in impact and vibration. This vibration and noise will not only affect the normal operation of the equipment but may also have a negative impact on the overall performance of the equipment.

Damage to rolling elements and rings

When the bearing clearance is too large, the contact area between the rolling element and the inner and outer rings will decrease, and the contact stress will increase. This high-stress state can cause severe wear and peeling on the surfaces of the rolling elements and rings. In addition, excessive clearance may also cause uneven load distribution on the rolling elements during rolling, which can accelerate the damage to the rolling elements and rings.

Bearing heating

When the bearing clearance is too large, the friction between the rolling elements and the inner and outer rings will increase, generating a large amount of heat. This heat will not only cause the bearing temperature to rise but also may cause thermal damage to the bearing. In addition, excessive bearing clearance may also lead to poor lubrication, further exacerbating the heating and wear of the bearing.

Bearing loosening

When the bearing clearance is too large, the fixation of the bearing on the shaft may become unstable, causing the bearing to loosen. This looseness will not only affect the rotation accuracy and stability of the bearing but may also cause damage to the shaft and bearing seat.

Equipment performance degradation

Excessive bearing clearance has a direct impact on the overall performance of the equipment. For example, in a reducer, excessive bearing clearance will cause the reducer to vibrate more during operation, thereby reducing the service life and performance of the reducer. In addition, excessive bearing clearance may also affect the accuracy and stability of the equipment, causing the equipment to fail to work properly.

Increase maintenance costs

Failures and damage caused by excessive bearing clearance will increase the maintenance cost of the equipment. Because it is necessary to replace damaged bearings and repair equipment frequently, this will not only consume a lot of time and workforce but also increase the downtime of the equipment, thereby affecting production efficiency.

Safety hazards

Excessive bearing clearance may also cause safety hazards because loose bearings and vibrations may cause equipment parts to fall off or be damaged, posing a threat to operators and people around the equipment. In addition, excessive bearing clearance may also cause abnormal noise and vibration during the rotation of the equipment, causing damage to the hearing and physical health of the operator.

3. Adjustment method of bearing clearance

In order to avoid failures and damage caused by excessive bearing clearance, the bearing clearance needs to be adjusted. The following are several commonly used bearing clearance adjustment methods:

Adjusting axial clearance with shims

Adding or reducing shims between the inner and outer rings of the bearing can achieve the purpose of adjusting the clearance. This method is simple and easy, but it is necessary to pay attention to the thickness and material selection of the shims to avoid excessive or too small clearance affecting the bearing performance.

Adjusting the clearance by the spacer method

Spacers are installed on the inner and outer rings of the two bearings. By adjusting the thickness of the spacers, the bearing preload can be changed to adjust the clearance. This method is suitable for occasions where the clearance needs to be adjusted accurately.

Ring adjustment method

Axial clearance adjustment is achieved by replacing the bearing gasket and bearing seat. This method requires removing the original gasket or bearing seat first, then replacing the gasket or bearing seat of different thicknesses according to the needs, and finally installing the new bearing seat back on the shaft and tightening the relevant parts. This method is suitable for occasions where a large range of clearance adjustments is required.

4. Precautions for adjusting bearing clearance

When adjusting the bearing clearance, the following points need to be noted:

Keep clean

During the adjustment process, keep the bearing and the working area clean and tidy, especially metal debris, foreign matter and other impurities. Once impurities enter the bearing, it will have a serious impact on the normal operation of the bearing.

Gradual adjustment

When adjusting the axial clearance, it is recommended to proceed step by step and slowly increase the debugging amount. Avoid too much adjustment at one time to affect the working accuracy of the equipment.

Follow technical specifications

Axial clearance adjustment requires certain experience and ability, and it is best to adjust according to the technical specifications of the bearing manufacturer. Ensure that the preload and axial clearance are controlled within a reasonable range.

Regular inspection

Regularly check and adjust the bearing clearance to ensure that the bearing clearance is always within a reasonable range. It helps to detect and deal with potential faults and damage in a timely manner and extends the service life of bearings and equipment.

In short, excessive bearing clearance is one of the common faults in bearing work, which has a significant impact on the rotation accuracy, vibration, noise, life, etc., of the bearing. In order to avoid faults and damage caused by excessive bearing clearance, the bearing clearance needs to be adjusted. During the adjustment process, attention should be paid to keeping clean, adjusting gradually, following technical specifications, and regular inspections. Through reasonable adjustment and maintenance, it can be ensured that the bearing clearance is always kept within a reasonable range, thereby extending the service life of bearings and equipment and improving the performance and stability of equipment.