Why is the bearing bad?

Core Tip: Bearings are precision parts and only some of the bearings are damaged in practical applications. Most of the reasons for bearing damage are much higher than the original estimated load, non-effective sealing, too tight
Bearings are precision parts and only some of the bearings are damaged in practical applications.

Most of the bearings are damaged for many reasons - beyond the original estimated load, non-effective seals, too tight bearing clearance caused by too small bearing clearance. Any of these factors have their particular type of damage and leave a special mark of damage. Therefore, inspecting the bearing of the damaged shaft, in many cases, its possible cause can be found. In general, one-third of the bearing damage is caused by fatigue damage, and the other third is caused by poor lubrication. The other third is due to contaminants entering the bearing or improperly installed.

However, these types of damage are also related to industry. For example, most of the pulp and paper industry is due to poor lubrication or contamination resulting in bearing damage rather than material fatigue. Bearings are precision parts, so they require a very cautious attitude when used. Even if high-performance bearings are used, if they are used improperly, the expected performance will not be achieved and the bearings will be damaged easily. Therefore, the following matters should be noted when using bearings:

    1. Keep the bearings and their surroundings clean. Even if tiny dust that is invisible to the naked eye enters the bearings, it will increase the wear, vibration and noise of the bearings.

    Second, use the installation carefully and carefully Do not allow strong stamping, do not allow the hammer to directly hit the bearing, not allowed to pass the pressure through the rolling elements.

    Third, the use of appropriate and accurate installation tools Try to use special tools, try to avoid the use of cloth and short fibers and the like. Fourth, to prevent the corrosion of the bearing When taking the bearing directly by hand, you should wash the sweat on your hands and apply it with high-quality mineral oil before handling. In the rainy season and summer, pay special attention to rust prevention.

   However, under certain special operating conditions, bearings can achieve longer life than traditional calculations, especially at light loads. These special operating conditions are when the rolling surfaces (tracks and rolling elements) are effectively separated by a lubricant film and the surface damage caused by contaminants is limited. In fact, under ideal conditions, so-called permanent bearing life is possible. Bearing life The life of a rolling bearing is defined by the number of revolutions (or the number of hours of operation at a certain speed): Bearings within this life are subject to initial fatigue damage (flaking or missing) on ​​any of their bearing rings or rolling elements. However, whether in the laboratory test or in actual use, it can be clearly seen that the same bearing under the same working conditions has a different actual life. In addition, there are several different definitions of the bearing "life", one of which is the so-called "working life", which means that the actual life that a bearing can reach before it is damaged is caused by wear and damage, usually not caused by fatigue, but Caused by wear, corrosion, seal damage, etc.

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Engine sliding SKF bearing damage features

Core Tip: As the world's top bearing SKF bearings, the application is very extensive. In every industry, the characteristics of its damage are also different. Today we look at the damage characteristics of the engine sliding bearing. (1
As the world's top bearing SKF bearings, the application is very extensive. In every industry, the characteristics of its damage are also different. Today we look at the damage characteristics of the engine sliding bearing.

(1) Mechanical damage

The mechanical damage of the sliding bearing means that the alloy surface of the bearing bush has different degrees of groove marks. In severe cases, metal peeling occurs on the contact surface and a large area of ​​random scratches occurs; in general, the contact surface damage and ablation phenomenon exist simultaneously. The main cause of mechanical damage to the bearing is that it is difficult to form an oil film on the bearing surface or the oil film is seriously damaged.

(2), bearing cave erosion

Under the repeated action of the sliding bearing in the cylinder pressure impact load, the surface layer is plastically deformed and hardened by hardening, and the local deformation loss ability is gradually formed, and the grain is gradually formed and expanded continuously. Then, as the wear debris falls off, a hole is formed in the loaded surface layer. . Generally, when cavitation occurs in the bearing bush, the pit first appears, and then the pit gradually expands and causes cracking at the interface of the alloy layer, and the crack spreads in the parallel direction of the interface until peeling off. The main reason for the cavitation of the sliding bearing is that the oil flow is strongly disturbed due to the sudden change of the cross section of the structural elements such as the oil groove and the oil hole, and bubbles are formed in the vacuum region where the oil flow is disordered, and then the bubble collapses due to the pressure rise. eclipse. Cavitation is generally found in the high load area of ​​the bearing, such as the lower bearing of the main bearing of the crankshaft.

(3), fatigue pitting

Bearing fatigue pitting refers to the overheating of the bearing and the excessive bearing clearance due to over-loading of the engine, resulting in fatigue damage, fatigue pitting or fatigue shedding in the middle of the bearing. Most of this damage is caused by overload, excessive bearing clearance, or unclean lubricating oil and foreign matter mixed in the interior. Therefore, when using, care should be taken to avoid overloading the bearing. Do not operate at too low or too high speed; adjust the engine to a steady state when idling; ensure normal bearing clearance and prevent engine speed from being too high or too low; check and adjust cooling The working condition of the system ensures that the working temperature of the engine is suitable.

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