Essential Tips for Diagnosing Rolling Bearings
Source: China Bearing Network | Date: April 5, 2014
Rolling bearings are widely used in various types of equipment, and their condition directly affects the performance of rotating machinery. Especially in large-scale continuous production environments, they play a critical role in key components of major rotating equipment. Therefore, diagnosing defects in rolling bearings is an essential part of equipment maintenance and repair. One of the most effective methods for bearing diagnosis is vibration analysis. It's crucial to carefully select measurement points and signal collection techniques. To accurately reflect the bearing's condition, it's important to collect signals precisely. Usually, the measuring point should be located on the motor’s free end or the fan cover, particularly near the fixing screws, which provide better monitoring results. Regular data collection and spectral analysis are also vital. By comparing the collected data over time, you can detect subtle changes that may indicate early signs of failure. This method helps in identifying potential issues before they escalate into serious problems. In normal operation, rolling bearings exhibit strong regularity and repeatability. High-quality bearings typically show low vibration and noise levels at the beginning of use. As the bearing operates over time, the vibration and noise remain stable, with a simple spectrum containing only one or two frequency components. However, as the bearing ages, these levels begin to rise, and abnormal sounds may appear. At this stage, the kurtosis value increases, indicating the onset of a fault. Once the kurtosis value reaches a certain threshold, the bearing should be closely monitored. If the kurtosis value then decreases rapidly and vibration increases significantly, it suggests the bearing is entering a more advanced stage of failure. When vibration exceeds specifications like ISO 2372, it becomes clear that the bearing needs immediate replacement. Bearings in the late stages of failure often display severe issues such as cracks, wear, or damage to the raceway. These problems can occur within a short period, especially in larger and faster equipment. Therefore, once late-stage fault characteristics are detected, the bearing must be considered faulty and replaced promptly. Another challenge is counterfeit or substandard bearings, which can cause sudden and catastrophic failures. For example, a cracked cage or burned rings can lead to rotor locking and equipment damage. Early detection through vibration monitoring and spectral analysis is crucial. In the early stages, the vibration level might not be high, but the spectrum may show irregular patterns. Identifying these anomalies early can prevent major incidents. For rapid diagnosis, we focus on parameters like frequency and kurtosis. If both exceed acceptable limits, the bearing is considered faulty. This method has proven effective, with an accuracy rate over 90%, making it a cost-effective solution. Additionally, if low-frequency vibrations are significant, even without bearing-specific frequencies, it could still indicate a problem. Other factors like misalignment or imbalance should also be checked during diagnosis. Spectrum analysis remains a powerful tool. Even when vibration levels are low, analyzing the signal can reveal hidden issues. If the power spectrum shows unusual energy distribution or if the frequency matches known bearing faults, it's a sign of trouble. In summary, proper diagnosis of rolling bearings requires attention to vibration patterns, spectral analysis, and timely maintenance. With the right approach, many potential failures can be prevented, ensuring smooth and reliable operation of the equipment. Related Articles: - The stability of grease and its impact on rolling bearings - SKF bearing performance and selection of ultrasonic low-noise bearings This article was originally published on China Bearing Network. Link: http://www.chinabearing.net Please cite the source: China Bearing Network.
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