In mechanical equipment, bearings are an essential part, and in order to reduce the coefficient of friction and support the mechanical rotating body, we often need to use bearings. However, in the daily use of machinery and equipment will often be due to environmental factors and human operating factors caused by a certain damage to the bearing, at this time we need to replace the bearing or find manufacturers to carry out maintenance, which undoubtedly in the use of cost caused a certain amount of pressure, therefore, understand the bearing damage mechanism, Clear factors affecting bearing quality are conducive to our better use.
The wear of the bearing is generally caused by the entry of foreign bodies into the inside of the bearing.
1)Foreign bodies entering the inside of the bearing can cause bearing grinding damage, abrasion, groove marks, circumference lines and debris pollution. 1. Grinding damage: When tiny foreign bodies enter the inside of the bearing, they may cause excessive grinding damage to the bearing. For example, metal particles produced during sand grains, grinding and machining, as well as metal particles or carbides from gears, wear or grind rollers and rollers.
2)This wear can cause axial clearance or internal clearance to expand, which in turn reduces the fatigue life of the bearing and leads to the eccentricity of the bearing. 2, Hemp Point and bruise: hard particles in the bearing rolling, can cause rollers and raceway hemp points and abrasions.
3)Improper cleaning of the housing and residual metal fragments or large particles of dust will lead to premature fatigue damage. 3. Groove Marks: The groove marks are extremely severe wear caused by fragments or metal particles.
4)These contaminants wedge into the soft cage material, resulting in grooves in the rolling member, which will affect the rolling contact geometry and reduce the bearing service life. 4, debris pollution: external debris pollution is usually caused by dust, sand grains and environmental particles, while internal debris pollution is generally by gears, spline, seals, clutches, brakes, joints and housings, such as improper cleaning or damage or peeling of components caused. Rigid particles swim in the bearing as the lubrication process, eventually causing bruising (compression) on the inner surface of the bearing. Indentation forms a protrusion, causing the concentration of surface stress, resulting in early damage to the bearing surface and reducing the life of the bearing.
Erosion or corrosion is one of the most serious problems encountered by anti-friction bearings.
The high precision machining of the bearing raceway and roller surface makes it highly susceptible to moisture and water corrosion. Erosion is usually caused by changes in the temperature in the housing, condensation of internal air, and continuous accumulation of water. Moisture or water often enters the bearing from a damaged, damaged or inappropriate seal ring. In addition, the bearing during disassembly, inspection, cleaning and drying improperly, will also cause such damage. When the bearing is cleaned and dried or when the bearing is placed in the warehouse, lubricating oil or other preservatives shall be applied and packed with protective paper. Whether new bearings or old bearings, should be placed in a dry area, wrapped in the original packaging, reducing the possibility of static corrosion before installation.
3.Insufficient bearing lubrication
Insufficient lubrication can be used to describe many possible damage situations. The common feature of these conditions is that the lubricant cannot be fully separated from the surface of the bearing rolling and sliding contact during the bearing operation. For different bearing systems, it is important to properly design the amount, type, grade, supply system, viscosity and additives of the required lubricant based on experience, load, speed, sealing system, operating conditions and life expectancy.
If these factors are not properly taken into account, bearing performance and its operating performance may not achieve the desired results. Bearing damage caused by insufficient lubrication performance is very different, may be very slight thermal discoloration with roller big end abrasion, may also be the bearing overall lock with extreme metal distortion. There is also a situation where the bearing undergoes a dry start and is accompanied by extreme metal distortion, but its surface remains bright; this phenomenon occasionally occurs. This is because during the start-up phase, due to metal contact with metal, the bearing is damaged by heat, and then, once the lubricant reaches the bearing, the bearing eventually cools down.
The bearing then tries to "repair" itself to disguise the initial metal twist and thermal discoloration. Secondary damage is more pronounced, and it often obscures the initial problem and subsequent bearing damage. This typical performance of bearing damage is caused by local high heat and metal flow in the bearing, thus changing the original bearing geometry and bearing material. Any visible metal cracks, scratches, heat marks, deformations, or geometric changes can make the bearing waste and therefore no longer be available.
Excessive preload can produce a lot of heat and lead to bearing damage. The damage form is similar in appearance to the damage caused by insufficient lubrication. These two triggers are often confused, so a thorough examination is required to determine the root cause of the problem.
Lubricants suitable for general operation may not be suitable for bearings with high preload, as the strength of the oil film may not be sufficient to carry the ultra-high load. Under high preload, another form of damage may occur even when extreme pressure lubricants capable of carrying heavy loads are used. Although the lubricant can cope with the load and prevent rolling members or raceway scratches, heavy loads can cause premature fatigue peeling of the secondary surface layer.
The appearance of this type of peeling and the resulting bearing life problems will depend on the bearing's preload and carrying capacity.
5.Bearing operation and Installation
Care should be taken when operating and assembling bearings, so that the rolling body, raceway surface and edges must not be damaged. If there is a deep chisel on the surface of the raceway, or if the rolling body is hit or deformed, the metal near the damaged area will protrude accordingly. When the rolling member passes through these damaged surfaces, high stress is generated and local premature peeling occurs. The direct effect of grooves and deep marks is to make the bearings rough and appear vibrating and noisy.