Four stages of bearing damage

Bearing failure stage 1

Only superficial damage, friction and slight impact. During this period, there is extremely high frequency vibration.

Friction-the earliest stage is greater than 20KHz

This frequency cannot be heard (without the help of tools)

Noise caused by insufficient lubrication

Very short impact

Bearing failure stage 2

Minor surface or superficial damage, friction and slight impact. In this stage, the amplitude of ultra-high frequency vibration increases, the vibration is large enough to arouse resonance, and the fault frequency is presented on the spectrum.

Bearing failure stage 3

Minor damage develops into more serious damage, and the bearing will fail in various ways for various reasons. For example, the amplitude of ultra-high frequency vibration continues to rise.

Bearing failure stage 4

Widely serious damage occurs, and the damage of one component will cause damage to other components, and complete failure of the bearing will occur soon. However, the ultra-high frequency vibration during this period may be reduced.

Main factors affecting the dynamic load capacity of bearings

1. The influence of material.

Due to different smelting methods, the size, distribution and content of inclusions in bearing steel are also different. This material difference will have a positive or negative effect on the bearing's load-bearing capacity. The basic rated dynamic loads of bearings listed in the bearing size and performance table are based on vacuum degassed bearing steel as the basic material. If ordinary electric furnace bearing steel is used, the load capacity of the bearing will decrease to varying degrees. On the contrary, if bearing steel or other equivalent steel is smelted by methods such as vacuum remelting, electroslag remelting, etc., the load capacity of the bearing will be improved to varying degrees.

2. Influence of temperature

Generally, the operating temperature that bearings can withstand can reach 120°C. For working conditions exceeding this limit temperature, bearings made of special (stable) heat treatment or special (heat-resistant) materials should be used. If bearings are often used at temperatures above 120°C, or at extremely high temperatures for a very short time, the structure of the bearing will change, resulting in a decrease in the bearing load capacity. The influence relationship can be expressed by the following formula:

Gr=gr

Where Gr is the basic rated dynamic load (N) corrected by temperature

gr temperature factor, refer to the following table for selection

3. Influence of hardness

The surface hardness of bearing parts is generally 60-65HRC. However, in some applications, the actual hardness is lower than the specified range. For example, high-temperature bearings that have been subjected to high-temperature tempering treatment, certain needle roller bearings that directly use the shaft neck and bearing box hole as raceways, etc. The reduction of the surface hardness of the bearing material, especially when it drops below 58HRC, will lead to a corresponding reduction in the bearing load capacity. Its influence relationship can usually be expressed by the following empirical formula:

GH =gH C

gH=(H/58) 3.6

Where GH is the basic rated dynamic load corrected by the material hardness;

H is the hardness HRC value;

gH is the hardness factor.