What is the cause of the falling off of the needle roller bearing surface?


Part of the bearing dynamic surface material falls off […]

Part of the bearing dynamic surface material falls off like fish scales, a phenomenon called fatigue spalling. During the operation of the dynamic bearing, it is subjected to a certain load, even if it is a static load, but for the steel ball and the raceway, the stress is reciprocating, and the material will be dynamic fatigued so that the bearing can reach its life. In addition, there are several different definitions of bearing "life", one of which is the so-called "working life", which indicates that the actual life that a needle roller bearing can achieve before it is damaged is due to wear, damage is usually not caused by fatigue, Instead, it is caused by wear, erosion, seal damage, etc.


However, whether in laboratory tests or in actual use, it can be clearly seen that the actual life of bearings with the same appearance under the same working conditions is very different.


The number of revolutions in the life of the bearing (or the number of hours of work at a certain speed), definition: the needle roller bearing within this life should have initial fatigue damage (peeling or defect) on any bearing ring or moving body. Most bearings fail for a number of reasons - exceeding the original estimated load, ineffective sealing, too small bearing clearance due to a tight fit, etc.


Each of these factors has its own specific pattern of damage and leaves specific traces of damage. Therefore, when inspecting the damaged bearings, in most cases, the possible causes can be found. Generally speaking, one-third of the needle roller bearing damage is caused by fatigue damage, and the other one-third is caused by poor lubrication. The other third is due to contamination entering the bearing or improper installation.


However, these damage patterns are also industry-specific. For example, in the pulp and paper industry, bearing damage is more likely to be caused by poor lubrication or contamination than by material exhaustion.


loud metal noise
Reason 1: Abnormal load, countermeasures: correct fit, study bearing clearance, adjust and load, correct the position of housing shoulder.
Reason 2: Poor installation, countermeasures: machining accuracy of shaft and housing, improve installation accuracy and installation method.
Reason 3: Insufficient or unsuitable lubricant, countermeasure: replenish lubricant and select appropriate lubricant.
Reason 4: The rotating parts are in contact, and the countermeasure: modify the contact part of the curved seal.


Regular noise
Reason 1: Indentation, rust or scars on the rolling surface caused by foreign matter, countermeasures: replace the bearing, clean the relevant parts, improve the sealing device, and use a clean lubricant.
Reason 2: (after carburizing of steel) surface deformation, countermeasures: replace the bearing and pay attention to its use.
Reason 3: The raceway surface is peeled off, and the countermeasure: replace the needle roller bearing.



Irregular noise
Reason 1: The clearance is too large. Countermeasures: study the fit and bearing clearance, and modify the preload.
Reason 2: Intrusion of foreign bodies, countermeasures: study and replace bearings, clean relevant parts, improve sealing devices, and use clean lubricants.
Reason 3: Spherical surface damage, peeling, countermeasure: replace the bearing.


Abnormal temperature rise
Reason 1: Too much lubricant, countermeasure: reduce lubricant, use it in moderation, and choose a harder grease.
Reason 2: Insufficient or unsuitable lubricant, countermeasures: replenish lubricant and select appropriate lubricant.
Reason 3: Abnormal load, countermeasures: modify the fit, study the bearing clearance, adjust the preload, and modify the shoulder position of the housing.
Reason 4: Poor installation, countermeasures: Improve the machining accuracy, installation accuracy and installation method of the shaft and housing.
Reason 5: The creep of the mating surface, the friction of the sealing device is too large, the countermeasures: replace the needle roller bearing, study the fit, modify the shaft and housing, and change the sealing form.


Vibration is high (shaft runout)
Reason 1: (after steel carburizing) surface deformation, countermeasures: pay attention to the bearing replacement operation.
Reason 2: peeling, countermeasure: replace the bearing.
Reason 3: Poor installation, countermeasures: modify the right angle of the shaft, the shoulder of the housing, and the right angle of the side of the gasket.
Reason 4: Intrusion of foreign objects, countermeasures: replace bearings, clean various parts, improve sealing devices, etc.
Excessive lubricant leakage, discoloration
Reason: too much lubricant, foreign matter intrusion, foreign matter generated by wear powder, etc. Countermeasures: use lubricant in moderation, study the replacement of lubricants, study the replacement of needle roller bearings, and clean the housing.

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