Failure Analysis

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Bearing Failure Analysis

1. To assist customers to pay attention to the accuracy of the spindle, the correct installation and application of the spindle.
2. To assist customers to choose the most suitable bearing from the vision of processing.

Seizure

Melting at ball pitch intervals

Excessive preload

Slipping

Slip phenomenon, cross texture on the surface of the steel ball

Spindle loses rigidity or insufficient preload

Indentation

Indentation and pit on raceway

Impurities enter during bearing cleaning, packaging, and spindle installation、 crushing injury caused by hard foreign matter

Flaking

Raceway breakage

The abnormal working surface of the bearing appeared flaking, which may be caused by misalignment of the bearing during installation, excessive warpage of the spindle, and poor machining accuracy of the housing

Rusting

Rusting of raceway

Water in bearings, or condensation generation

Fretting corrosion

Brown or red wear particles on the metal contact surface

When the interference is insufficient or the axial compression force on the bearing end surface is insufficient, after a certain period of operation, the mating surface undergoes elastic deformation due to stress, resulting in small gaps, and in severe cases, metal sliding occurs under pressure.

High temperature burns

Burn of rolling element

The discoloration of the ring and the steel ball can be considered as a sign of bearing burns. During the operation of the bearing, the temperature is the highest for the steel ball, followed by the inner ring, and the lowest for the outer ring. Therefore, the discoloration of the steel ball is the most severe, causing carbonization damage due to high temperatures. The main factors causing burns are excessive bearing preload, poor lubrication and cooling, and improper installation

High temperature burns

Burn of raceway

The discoloration of the ring and the steel ball can be considered as a sign of bearing burns. During the operation of the bearing, the temperature is the highest for the steel ball, followed by the inner ring, and the lowest for the outer ring. Therefore, the discoloration of the steel ball is the most severe, causing carbonization damage due to high temperatures. The main factors causing burns are excessive bearing preload, poor lubrication and cooling, and improper installation

Cage melting and fracture

Cage melting and fracture

$Cage-melting-and-fracture$
Improper installation or excessive axial force, misalignment of the inner and outer rings of the bearings, or stress on one side of the rolling element can cause significant clamping force on the cage, which can lead to wear and fracture of the cage; Hard impurities can cause interference between the cage and the rolling element, exacerbating the wear of the cage and generating abnormal additional loads, leading to cage fracture

Bearing ring deformation

Changes in dimensional accuracy of bearing rings: changes in roundness of outer rings, inner ring bores, raceway groove, etc.

Poor vertical deviation between the end face of the shaft and the shaft or bending of the spindle: When spindle bending occurs, the possibility of deformation of the 1 # bearing or the 4 # bearing is generally the greatest. There is a misalignment of the center point between the spindle and the motor. Torsion occurs during operation, resulting in certain damage to the bearing

Outer ring sliding

There are rotating marks on the outer circumference of the ring

Poor parallelism and flatness of the spindle spacer ring (stepped casing); Insufficient pressing amount of end cap

Offset load

The bearing raceway surface has uneven stress traces

Caused by improper assembly or excessive axial force

Discoloration of lubricating grease

The bearing grease turns yellow, reddish brown, black, gray, etc

Grease discoloration is one of the manifestations of bearing failure. There are many reasons : grease is oxidized, oil film rupture caused by abnormal load, impurities entering the raceway surface, dry friction after oil film rupture, wear particles entering the grease after the raceway is worn, high temperature of the bearing, water entering the oil inside the bearing, etc.

Wear (remove impurities）

The running trace of the raceway surface or the surface of the rolling element is deep and the wear is obvious

Excessive preload