Bearing cleanliness
The cleanliness of the bearing is one of the important indicators for evaluating the quality of the bearing. The cleanliness has the most obvious impact on the quality of the bearing, especially its dynamic performance and service life. Studies have shown that 90% of all the damage of rolling bearings is caused by insufficient lubrication, and 70% of them are caused by the contamination of the bearing by impurities. This shows that cleanliness is very important.
There are many failure modes of rolling bearings, and some of the failures of abrasive wear and indentation are caused by cleanliness problems.
Several failure modes related to cleanliness in abrasive wear:
01 The surface of the raceway is fuzzy and dull, which is caused by rough impurities in the bearing.
02 The surface of the raceway has a bright area, the reason is that there are fine impurities in the bearing and the hardness is low.
03 The surface of the raceway and rolling element has deep scratches in the shape of thin lines in the circumferential direction. The reason is that there are large hard particles in the bearing.
04 The rolling elements have irregular wear marks, which are caused by vibration caused by impurities.
There are two types of indentation failure:
01 The static load is too large or the bearing is impacted.
02 There are hard particles inside the bearing. During the operation of the bearing, when the hard particles move to the load-bearing area, the indentation will occur.
It is well known that the lower the vibration and noise level of a bearing, the longer its fatigue life and the better its reliability. The cleanliness has a very large impact on the vibration and noise of the bearing.
Cleanliness will also have a great impact on the lubrication of the bearing. When the bearing is running, the thickness of the oil film is only sub-micron. If the mixed impurity particles are more than 10 microns, it will seriously affect the lubricating performance of the bearing and reduce the lubricant ( oil and grease) life.
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