Classification of Bearing Fault Diagnosis Techniques
The company mainly produces three core series of products: cylindrical roller bearings, self-aligning roller bearings, and thrust self-aligning roller bearings. The product can be adapted to multiple industrial fields such as metallurgical equipment, mining machinery, heavy machinery, engineering equipment, etc., and can meet the operational and load-bearing requirements of equipment under different working conditions.
SZ Bearings
The main diagnostic techniques for ball bearings include vibration diagnosis, ferrography, temperature diagnosis, acoustic diagnosis, oil film resistance diagnosis, and fiber-optic monitoring. Among these, vibration, ferrography, and temperature diagnosis are the most widely used.
1. Vibration Diagnosis Technology: When fatigue spalling, indentations, or localized corrosion occur on the working surfaces of bearing components, periodic pulsed signals appear during the operation of ball bearings. These periodic signals can be captured by sensors (velocity-type or acceleration-type) mounted on the bearing housing, and bearing faults can be diagnosed by analyzing the vibration signals.
Features: Vibration diagnosis technology is widely applied; it enables online monitoring; diagnosis is rapid, and the diagnostic theory is well-established. Scope of Application: Particularly suitable for fault monitoring of bearings in rotating machinery.
2. Ferrography Diagnostic Technology: Bearing wear particles are closely linked to the bearing’s operating condition. When lubricating oil containing wear particles is passed through a strong magnetic field, the particles settle on a ferrographic plate according to specific patterns. The plate can be examined qualitatively under a ferrographic microscope or tested using quantitative instruments to assess the bearing’s operating condition.
Features: No need to disassemble the machine; low investment with excellent results; capable of detecting early-stage fatigue failure in bearings; suitable for studying wear mechanisms.
Scope of Application: Suitable for fault diagnosis of oil-lubricated bearings; less suitable for grease-lubricated bearings.
3. Oil Film Resistance Diagnosis Technology
In well-lubricated bearings, the oil film creates significant electrical resistance between the inner and outer rings. Therefore, by measuring the resistance between the inner and outer rings, bearing abnormalities can be identified.
Features: The same evaluation criteria can be applied across different operating conditions. However, it is less effective for diagnosing abnormalities such as surface spalling, indentations, and cracks. Scope of Application: Suitable for applications where the rotating shaft is exposed.
4. Fiber Optic Monitoring and Diagnostic Technology
Fiber optic monitoring is a diagnostic technique that directly extracts signals from the surface of bearing rings. A displacement sensor made of an optical fiber bundle consists of a transmitter fiber bundle and a receiver fiber bundle. Light emitted from the transmitter fiber bundle is reflected back through the gap between the sensor end face and the bearing ring surface, received by the receiver fiber bundle, and converted into an electrical signal by a photodetector. By analyzing and processing this electrical signal, the operating condition of the bearing can be assessed.
Features: Fiber-optic displacement sensors offer high sensitivity; signals are extracted directly from the bearing surface, improving the signal-to-noise ratio; they can directly reflect the manufacturing quality, surface wear, load, lubrication, and clearance conditions of ball bearings.
Scope of Application: Suitable for machines where the sensor can be installed inside the bearing housing.
5. Temperature Diagnostic Technology
If a bearing develops an abnormality, its temperature will change. Therefore, ball bearing failures can be diagnosed based on temperature changes; however, the ability to identify specific abnormalities is limited.
Features: Simple diagnosis; effective for detecting bearing scorching. Scope of Application: Suitable for simple, routine diagnosis of bearings in machinery.
6. Acoustic Emission Diagnostic Technology
In metallic materials, dislocations in the internal crystal lattice, slip at grain boundaries, or the formation and propagation of internal cracks all require the release of elastic waves; this phenomenon is known as acoustic emission. When spalling or cracks occur in ball bearings, different types of acoustic emission signals are generated, which can be used to assess the bearing’s operating condition.
Features: Rapid and simple diagnosis; supports online monitoring. Scope of Application: A new technology developed in recent years, it is currently used infrequently in bearing condition monitoring.