How to tell if a cylindrical roller bearing is faulty or worn?

As a key rotating support component in mechanical equipment, the operating status of cylindrical roller bearings directly affects the working performance and safety of the whole machine. During long-term operation, bearings will inevitably have varying degrees of wear or failure. In actual use, bearing failures are usually manifested as unstable operation, increased noise, abnormal temperature rise, and increased vibration. Through the monitoring and analysis of these external signals, it is possible to preliminarily determine whether there is a problem with the bearing. Among them, vibration is the most intuitive and most commonly used diagnostic method. Under normal circumstances, the bearing should remain stable during operation. If periodic or irregular vibration signals appear, it often indicates that the internal structure may be damaged, such as raceway peeling, roller deformation, or loose cage. By collecting data through special vibration sensors and combining frequency analysis technology, the type and location of the fault can be more accurately identified.
In addition to vibration, the sound emitted during operation is also one of the judgment bases. Normal bearings will hardly make obvious noise under good lubrication, but once sharp, intermittent or friction-like sounds appear, it usually means poor lubrication, scratches on the roller surface, or foreign matter in the raceway. Sound changes are often a sign of worsening problems and should be given sufficient attention.
Temperature change is also an important reference indicator. During normal operation, the bearing will generate temperature rise due to frictional heat, but the temperature rise should remain stable within a reasonable range. If the bearing temperature is found to continue to rise or suddenly become high, it may be due to local overheating caused by insufficient lubrication, increased internal wear or overtightening. Monitoring the bearing position through infrared temperature measuring equipment or temperature sensors can timely detect temperature abnormalities and take intervention measures.
During equipment shutdown and maintenance, direct evidence of bearing failure can also be found through visual observation and manual inspection. For example, after disassembly, the rollers and raceways can be checked for pitting, scratches, cracks or surface discoloration. Deformation of rolling elements and cracking or breaking of cages are also typical mechanical damage characteristics. Tactile testing can determine whether the rolling is smooth. If there is sticking, astringency or looseness, it means that the bearing structure may have undergone irreversible changes.
Changes in lubrication status can also be used as one of the judgment bases. By observing the color, odor and metal impurity content of grease or lubricant, it can be determined whether there is overheating, contamination or wear particles. Normal lubrication should be uniform, without obvious discoloration or sediment. If the lubricating medium turns black, smells or metal powder is found, it usually indicates that serious friction and wear have occurred inside.
The service life of the bearing is often closely related to the installation and use conditions. Excessive load, installation deviation, loose or tight fit between the shaft and the hole, poor sealing, improper lubrication, etc. may all lead to early failures. Therefore, when judging whether the bearing is worn or damaged, it is necessary not only to pay attention to its operating performance, but also to conduct a comprehensive analysis in combination with the equipment operation history, maintenance records and use environment.