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Causes of FAG failure

wallpapers Tech 2021-03-12
Causes of FAG failure
A deteriorated layer of FAG bearing
In the grinding process of FAG bearing , the surface layer of the workpiece will be affected by the cutting force, compression force, and friction force of the grinding wheel. In particular, the role of the latter two makes the surface layer of the workpiece form a highly directional plastic deformation layer and a work-hardened layer. These metamorphic layers will inevitably affect the changes in the residual stress of the surface layer.
(1) Cold plastic deformation layer
In the grinding process of FAG bearings, every tick is equivalent to a cutting edge. However, in many cases, the rake angle of the cutting edge is negative. In addition to the cutting action, the abrasive particles are subjected to squeezing (plow action) on the surface of the workpiece, leaving a significant plastic deformation layer on the surface of the workpiece. The degree of deformation of this deformation layer will increase with the degree of blunt grinding of the grinding wheel and the increase of the grinding feed.
(2) Thermoplastic deformation (or high-temperature deformation) layer
The instantaneous temperature formed by the grinding heat on the working surface makes the elastic limit of the surface layer of the workpiece at a certain depth drop sharply, and even reaches the level of elasticity disappearing. At this time, the working surface layer is freely stretched under the action of the grinding force, especially the compression force and friction force, and the surface is compressed (more plowed) due to the limitation of the base metal, causing plastic deformation in the surface layer. The high-temperature plastic deformation increases with the increase of the surface temperature of the workpiece under the condition of the same grinding process.
(3) Work hardened layer
Sometimes microhardness and metallographic methods can be used to find that the hardness of the surface layer increased due to processing deformation.
In addition to grinding processing, the surface decarburization layer caused by casting and heat treatment heating, if not completely removed in the subsequent processing, remains on the surface of the workpiece will also cause the surface to soften and deteriorate, leading to the early failure of the bearing.

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