Bearing failure analysis method

Source: Bearing network time: 2013-06-09

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In the process of dissecting the bearing failure; often encounter many confusing appearances; the results of various tests may be opposite each other or the primary and secondary; this requires repeated trials, proofs; to obtain a satisfactory basis or counter-evidence. Proper analysis of methods, procedures, processes; ability to find the real cause of failure.
Under normal conditions, the analysis of bearing failure can be roughly divided into the following three processes: the collection of ineffective and scene data, the microscopic view of the ineffective matter and the microscopic analysis.
1. The collection of invalid materials and set materials collects as many parts and fragments as possible of the ineffective things. It is fully aware of the operating conditions, application process and production quality of the failed bearings. Details include:
.1) The drawing conditions of the bearing such as the load, rotation speed and working condition of the main engine.
.2) failure conditions of bearings and other parts of their associated parts; type of bearing failure.
.3) Recording of the bearing operation of the bearing. Whether there is abnormal operation during the operation of the operation.
.4) Whether the practical load accepted in the bearing operation can match the original depiction.
.5) The actual speed of the bearing operation and the frequency of the different speeds.
.6) Can there be a sharp increase in temperature or smoke when it fails? Can there be noise and oscillation?
.7) Whether there is corrosive medium in the working environment; whether there is any special oxidation color or other staining between the bearing and the journal.
.8) Recording of the bearing device (including the re-inspection condition of the bearing standard in the front of the device); original bearing clearance, device and alignment; how rigid the bearing seat and the base; whether the device can be abnormal.
.9) Whether the bearing operation can have thermal expansion and power transmission changes.
.10) the smooth condition of the bearing; including the trademark, composition, color, viscosity, impurity content, filtration, replacement and supply status of the smoothing agent; and collecting the sediment.
.11) Whether the material selection of the bearing is correct; whether the quality of the material can meet the requirements of the relevant specifications or drawings.
.12) Whether the manufacturing process of the bearing can be normal; whether the appearance can be plastically deformed; whether there is any surface grinding burn.
.13) Recording of the correction and protection of the failed bearing.
.14) Failure conditions of the same batch or similar bearings.
In the collection of practical set data operations; it is very difficult to fully satisfy the above requirements. However, the more information collected, will undoubtedly be more conducive to getting the correct analysis.
2. Microscopic view of the microscopic view of the failed bearing (including the measurement of the measurement and appearance of the scale public service); is the most important part of the failure analysis. The overall appearance of the view; can know the outline of the bearing failure and the characteristics of the damaged part; Reasons; investigate the size, shape, location, quantity and characteristics of the shortcomings; and intercept the appropriate parts for further microscopic viewing and analysis. The microscopic views include:
.1) Change in shape and scale (including vibration analysis, dynamic function analysis and raceway roundness analysis).
.2) Change in the clearance.
.3) Can there be a corrosion appearance; in the sputum area; it is a type of corrosion; can be directly related to failure.
.4) Can there be cracks; the shape of the crack and the nature of the fracture.
.5) Wear is a type of ;; how effective it is for failure.
.6) Investigate the condition and location of the external discoloration of the bearing parts to determine its smooth condition and appearance temperature effect.
.7) The primary investigation of the failure zone is to investigate abnormal wear, foreign particle embedding, cracks, abrasions and other shortcomings.
.8) Cold pickling or hot pickling to check the original appearance of the bearing parts for soft spots, decarburization and burns; especially for surface grinding burns.
.9) Using X-ray stress measurement equipment to measure the stress change before and after bearing operation.
The results of the microscopic review; sometimes the way and cause of failure can be fundamentally identified; but the nature of the failure must be further determined; more basis must be obtained; microscopic analysis is done.
3. The microscopic analysis of the microscopic analysis of the failed bearing includes optical metallographic analysis, electron microscopy analysis, probe and electron energy spectrum analysis, etc. The first is based on the microscopic arrangement of the failure feature area and the analysis of the fatigue source and crack source for the failure analysis. More abundant criteria or counter-evidence. The most common and most common method in micro-analysis is optical metallographic analysis and external hardness testing. The content of the analysis should include:
.1) Whether the quality of the data can meet the relevant specifications and depicting needs.
.2) The basic arrangement of the bearing parts and the quality of the heat treatment can meet the relevant requirements.
.3) Whether there are decarburization layers, torsite and other external processing enthalpy layers in the surface layer.
.4) Measure the depth of the outer layer of the carburized layer and the layers of the multilayer metal; the shape and depth of the corrosion pit or crack; and determine the cause and nature of the crack according to the shape of the crack and the characteristics of the two sides.
.5) Discriminating the degree of deformation, temperature rise, data variety and process progress according to grain size, arrangement deformation, partial phase transformation, recrystallization, phase collection, etc.
.6) Measure the hardness, hardness uniformity and hardness change of the failure zone.
.7) Fracture investigation and analysis. Qualitative analysis and measurement of fractures using scanning electron microscopy.
.8) Electron microscopy, probe and electron spectroscopy can measure the composition of the fracture in the analysis of the source of fatigue and the source of the crack; the nature of the fracture and the cause of the crack are found.
The three processes of the above-mentioned analysis of bearing failure analysis are a process of gradual deepening from the outside to the inside. The details of each process should be based on the type and characteristics of the bearing failure; depending on the detailed situation; but the analysis process is Indispensable. And throughout the profiling process; the results of the analysis should always be linked to many factors affecting bearing failure; inductive thinking.

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