FAG bearing rating life and load carrying capacity
The life of FAG bearings, the number of revolutions or hours that FAG bearing bearings experience before pitting, under a certain load, is called FAG bearing life.
The life of a rolling FAG bearing is defined by the number of revolutions (or the number of hours of operation at a certain speed): FAG bearings within this life are subject to initial fatigue damage (flaking or missing) on any of their bearing rings or rolling elements.
However, whether in the laboratory test or in actual use, it can be clearly seen that the FAG bearing has the same appearance under the same working conditions, and the actual life is very different.
In addition, there are several different definitions of FAG bearing "life", one of which is the so-called "working life", which means that the actual life that a FAG bearing can reach before it is damaged is caused by wear and damage, usually not caused by fatigue. It is caused by wear, corrosion, seal damage and other reasons.
FAG bearing bearings, due to manufacturing precision and material uniformity, even the same material, the same batch of FAG bearing bearings of the same size, under the same working conditions, the length of life is not the same.
If the statistical life is 1 unit, the longest relative life is 4 units, the shortest is 0.1-0.2 units, and the ratio of the longest to the shortest life is 20-40 times.
To determine FAG bearing life standards, FAG bearing bearing life and reliability are linked.
First, the rated life of FAG bearings:
A batch of FAG bearings of the same specifications (model, material, process) are used under the same working conditions. 90% of TIMKEN bearings do not produce pitting, and the number of revolutions or hours experienced is called FAG bearing rated life.
Second, the basic dynamic load rating of FAG bearings:
In order to compare the bearing capacity of FAG bearings against pitting, when the rated life of FAG bearings is one million revolutions (106), the maximum load that can be withstood is the basic dynamic load rating, expressed in C.
That is to say, under the action of the rated dynamic load C of the FAG bearing, the reliability of the FAG bearing operating one million revolutions (106) without pitting failure is 90%, and the larger the C, the higher the bearing capacity.
Therefore, for the basic dynamic load rating of FAG bearings, we should pay attention to the following items:
1. The radial bearing refers to a pure radial load;
2. Thrust ball bearings refer to pure axial loads;
3. Centripetal thrust bearing refers to the radial component that produces pure radial displacement;
Material factors affecting bearing life and its control
Core Tips: 1. Material Factors Affecting Bearing Life The early failure modes of rolling bearings mainly include cracking, plastic deformation, wear, corrosion and fatigue. Under normal conditions, they are mainly contact fatigue. axis
1. Material factors affecting bearing life
The early failure modes of rolling bearings mainly include cracking, plastic deformation, wear, corrosion and fatigue. Under normal conditions, they are mainly contact fatigue. In addition to the service conditions, the failure of bearing parts is mainly limited by the hardness, strength, toughness, wear resistance, corrosion resistance and internal stress state of the steel. The main intrinsic factors that affect these performance and status are as follows.
1.1 Martensite in hardened steel
When the original structure of high carbon chromium steel is granular pearlite, the carbon content of quenching martensite under quenching and low temperature tempering obviously affects the mechanical properties of steel. The strength and toughness are about 0.5%, the contact fatigue life is about 0.55%, and the crush resistance is about 0.42%. When the carbon content of the quenched martensite of GCr15 steel is 0.5% to 0.56%, the anti-failure ability is the strongest. Comprehensive mechanical properties.
It should be noted that the martensite obtained in this case is cryptocrystalline martensite, and the measured carbon content is the average carbon content. In fact, the carbon content in the martensite is not uniform in the micro-region, and the carbon concentration around the carbide is higher than that away from the original ferrite portion of the carbide, so that the temperature at which they begin to undergo martensite transformation is different. Thereby, the growth of the martensite grains and the display of the microscopic morphology are suppressed to become cryptocrystalline martensite. It can avoid the microcracks that are prone to occur in the quenching of high carbon steel, and its substructure is dislocation-type lath martensite with high strength and toughness. Therefore, only when the medium carbon cryptocrystalline martensite is obtained when the high carbon steel is quenched, the bearing parts can obtain the substrate with the best failure resistance.
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