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Before using NTN imported bearings, the bearing surface must first be inspected to determine if it meets our requirements and standards. The bearing surface inspection should be conducted under diffused light, paying close attention to cracks and the surface itself.
I. Bearing Rolling Noise: Even with minor damage such as spalling, the magnitude and quality of the rolling noise from a running bearing can be detected using a sound meter. Abnormal and irregular sounds will be emitted, which can be distinguished using a sound meter.
II. Bearing Vibration: Issues such as spalling, indentation, corrosion, cracks, and wear are all reflected in bearing vibration measurements. Bearing vibration is highly sensitive to damage to NTN imported bearings. Therefore, using specialized bearing vibration measuring instruments (such as frequency analyzers) can measure the magnitude of vibration, and the specific details of any abnormalities can be inferred through frequency analysis. The measured values will vary depending on the bearing's operating conditions and the sensor's installation location; therefore, it is necessary to analyze and compare the measured values for each machine beforehand to determine the judgment criteria.
III. Bearing Temperature: The bearing temperature can usually be estimated from the temperature outside the bearing housing. If the bearing outer ring temperature can be directly measured using an oil hole, that is even more suitable. Normally, the bearing temperature gradually rises with the start of operation, reaching a stable state after 1-2 hours. The normal bearing temperature varies depending on the machine's heat capacity, heat dissipation, speed, and load. If lubrication or installation is inadequate, the bearing temperature will rise rapidly, resulting in abnormally high temperatures. In this case, operation must be stopped and necessary preventative measures taken. Based on numerous test data, Table 4-1 lists the average outer ring temperature of bearings in various types of machinery during operation for reference. Because temperature is affected by lubrication, speed, load, and environment, the values in the table only show approximate temperature ranges. Using a thermal sensor can monitor the bearing's operating temperature at any time and automatically alarm or stop the bearing when the temperature exceeds a specified value to prevent bearing failure.
IV. Lubrication: Without proper lubrication, the fatigue life, friction, wear, temperature rise, and vibration of NTN imported bearings cannot be maintained. Analysis of bearing failure causes indicates that approximately 40% of bearing failures are related to poor lubrication. Therefore, proper lubrication is an effective measure to reduce bearing friction and wear.
During use, the load-bearing capacity, rotational accuracy, and friction-reducing performance of rolling bearings can change due to their inherent quality and external conditions. In fact, anything used will have its lifespan reduced over time.
However, it's important to note that when a bearing's performance indicators fall below the required specifications and it cannot function properly, it is considered bearing damage or failure. Once a bearing fails or encounters other unexpected situations, various abnormal phenomena will occur, such as machine or equipment stopping operation and functional impairment. Therefore, it is necessary to investigate the cause and take appropriate measures as soon as possible. Of course, rolling bearing damage is much more complex than damage to general mechanical parts. The characteristics of rolling bearing damage are its diverse manifestations and complex causes. Besides inherent factors in bearing design and manufacturing, most bearing damage is caused by external factors such as improper use, unreasonable support design, improper installation, poor lubrication, and inadequate sealing.
By now, you should understand some of the factors that contribute to rolling bearing damage. Therefore, studying the formation and causes of rolling bearing damage is of great significance. On the one hand, it can help improve usage methods, ensure the correct use of bearings, and fully utilize their intended performance. On the other hand, it can contribute to the development of new products with better performance. In addition to describing the precautions for using rolling bearings, installation methods, and operational monitoring, this article also focuses on introducing the forms and causes of damage to NTN imported bearings and the countermeasures that should be taken.
