Analysis of 10 common bearing failures and their causes:

Bearings are industrial consumables. If a fault occurs during operation, how to judge and deal with it is the key. Today I will introduce to you the causes and solutions of common bearing failures.

1. Bearing temperature is too high

When the equipment is running, the parts where the bearings are installed are allowed to have a certain temperature. When touching the shell of the mechanism with your hand, it should be normal if it does not feel hot. Otherwise, it indicates that the bearing temperature is too high.

reason:

The quality of the lubricating oil does not meet the requirements or has deteriorated, and the viscosity of the lubricating oil is too high;

The mechanism is assembled too tightly (insufficient clearance);

The bearing assembly is too tight;

The bearing race rotates on the shaft or in the shell;

Overload;

The bearing cage or rolling elements are broken, etc;

2. Bearing noise

Rolling bearings are allowed to make slight running noise during operation. If the noise is too loud or there are abnormal noises or impacts, it indicates that the bearing may be faulty.

reason:

Unqualified quality, internal impurities, improper clearance, etc;

Improper installation, such as installation that is too tight or too loose, incorrect installation position, unclean mating surface, etc;

The geometric tolerance of the bearing seat or shaft components deviates greatly, causing the bearing to be squeezed, deformed or poorly installed;

The quality of the lubricating oil does not meet the requirements or has deteriorated, and the viscosity of the lubricating oil is too high;

Bearings are subject to external interference, such as external vibration, impact, temperature changes, etc;

3. Metal peeling off the raceway surface

The rolling elements of the bearing and the painted surfaces of the inner and outer rings are subjected to periodic pulsating loads, resulting in periodic changing contact stresses.

Reason: When the number of stress cycles reaches a certain value, fatigue spalling will occur on the rolling elements or the working surfaces of the inner and outer ring raceways.

If the load on the bearing is too large, this fatigue will be exacerbated. In addition, improper installation of bearings and bent shafts can also cause raceway peeling. Fatigue spalling of bearing raceways will reduce the operating accuracy of the shaft and cause vibration and noise in the mechanism.

4. Crack defects

There are cracks in some notches.

Reasons: The impact load of the main machine is too large, and the interference between the main shaft and the bearing is large; there are also large peeling frictions that cause cracks; poor accuracy during installation; improper use (using a copper hammer, stuck large foreign objects) and friction cracks.

5. Bearing false Brinell indentation

During the micro-vibration period, the contact part between the rolling element and the raceway wheel develops wear due to vibration and shaking, resulting in imprints similar to Brinell indentations.

Reason: During transportation, the bearing vibrates and swings when it stops rotating. Swinging motion with small amplitude. Poor lubrication.

6. The cage is broken

Insufficient lubrication, broken rolling elements, skewed seat rings, etc. At this time, the usage conditions and lubrication conditions should be checked, and the cage selection should be re-examined.

7. Bearing misalignment, that is, eccentric loading

A sign of bearing misalignment is that the ball wear marks on the raceway are not parallel to the edge of the raceway.

Excessive eccentric load will cause abnormal temperature rise of bearings and bearing seats and wear of cage balls. Different bearing types have different allowable eccentric loads. Generally, spherical bearings have the best eccentric load capacity. However, other bearings can achieve the purpose of increasing a certain eccentric load capacity by optimizing the raceway geometry and dimensions.

8.Loose bearing fit

The loose fitting of the bearing leads to relative movement of the mating parts. If this relative movement is slight but uninterrupted, wear will occur, which is customarily called "creep".

This wear creates particles that oxidize to a special brown color, causing increased grinding and loosening.

If the looseness increases to significant movement of the inner or outer ring, the mounting surfaces (bore, outer diameter, and sides) will wear and heat, causing noise and shaking.

9.Plastic deformation

Uneven pits appear on the contact surface between the raceway and roller of the bearing, indicating that the bearing has plastic deformation.

reason:

Under the action of large static load or impact load, the local stress on the working surface of the bearing exceeds the yield limit of the material. This situation generally occurs in bearings rotating at low speeds.

10. Stripping

The running surface peels off and becomes obviously convex and concave after peeling off.

reason:

Excessive load and improper use

Poor installation

Poor shaft or bearing housing accuracy

Clearance is too small

Foreign body invasion

Rust occurs

Decreased hardness caused by abnormally high temperatures