Example of deep groove ball bearing cage fracture

A type of deep groove ball bearing in long-term use after inspection, found that the cage fracture, decomposition found that the raceway appeared local flaking. The bearing is very widely used, but in the process of many years of use, are for the emergence of cage fracture, raceway spalling phenomenon, this cage fracture is the cause of what?

The overall color of the faulty bearing is bright, the inner and outer ring surface is not seen damage; a steel ball where the cage pocket hole near the side of rivet riveting have been cracked off.

The outer ring of the bearing is cut open and found that the outer ring raceway bottom are more obvious discoloration contact track, track has become rough; inner ring raceway along the bottom of the groove appears along the entire circumference of the continued flaking, contact track slightly biased to the non-typing end side of the groove, is a light creep characteristics, cracked pocket hole near the fracture has been obvious wear thinning and produce flying edge, remove the rivets to separate the two pieces of cage, visible some cage pocket hole inner surface and steel ball Friction shiny, cracked pocket hole inner surface more obvious; where the steel ball surface is intact, all have different degrees of high temperature discoloration, but still have a metallic luster, cracked pocket hole where the steel ball appearance is not abnormal.

Faulty bearing is still rotating flexible, but there is a clear sense of vibration.

Test results: inner ring axial runout, outer ring axial runout are obviously exceed the standard provisions, indicating that the internal accuracy has deteriorated;

The size accuracy of the 7 steel balls in the bearing was tested, the measured steel ball diameter group difference is 0.8u m, slightly exceeding the standard requirements, including the cage cracking pocket hole in the steel ball size deviation is slightly larger.

Analysis of spalling parts

Scanning electron microscope observation of the inner raceway spalling parts, no inclusions and other material defects, spalling source at the metal convex ridge, convex ridge is arc-shaped distribution and gradually expand to the heart of the spalling, the spalling nature of fatigue spalling.

Spectral analysis of the spalling site, no other elements other than the matrix were found.

Hardness and metallographic organization

According to the results of the decomposition of the failure of the appearance of the inspection, selected the inner ring and a steel ball, respectively, to detect the hardness and hardening and tempering organization, the test results, the inner sleeve and steel ball hardening and tempering organization and hardness are in line with the provisions of the standard, see Table 3.

Further observation of the inner ring metallographic specimens, no high temperature characteristics and organizational abnormalities.

Several common defects in the forging process of bearing rings

How is bearing accuracy differentiated?

Several common defects in the forging process of bearing rings

How is bearing accuracy differentiated?