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Failure Case of Large FAG Spherical Roller Bearings

Source: FAG bearings  Tags: News

The FAG spherical roller bearing exemplified here is a main shaft bearing used in a wind turbine. It is understood that the large-scale spherical roller bearing bears a large axial load during use, which leads to the spherical roller bearing Under eccentric load, the entire set of bearings cannot be aligned, causing the surface of the shaft raceway to peel off, and ultimately leading to bearing failure. Next, Eric Bearing Limited will share with you the specific situation of the failure of this FAG spherical roller bearing under eccentric load.

1. Macro morphology of FAG spherical roller bearing failure under eccentric load

One side of the FAG spherical roller bearing is close to the gearbox, marked as side A; the other side is close to the blade, marked as side B. There are shallow spalling and rolling traces on the raceway surface A on both sides of the outer ring, and the surface of some areas is discolored, and there are circumferential running wear traces on the side of the end surface on the outer diameter surface; on the other side, there are circumferential wear traces and more on the raceway surface. Axial indentation, fretting corrosion marks on the outer diameter surface.

There are many peelings on the A side of the raceway surface on both sides of the inner ring, and the rolling is serious; the running wear traces of the B side are not obvious; there are squeezing and abrasion traces on the ribs at both ends, and there are obvious fretting corrosion traces on the inner diameter surface.   FAG 22211 E1 bearings online , pls click here :

Observing the spalling of the A-side raceway of the FAG bearing inner ring, it is found that the spalling direction expands axially inward from the A-side outer rib side.

There is peeling on the working surface of the roller on the A side, severe rolling, and the surface discoloration; there are signs of circumferential running wear on the two ends and the middle area of ​​the roller on the B side.

There are a lot of metal scraps, deep squeezing marks and running wear marks in the A-side cage pockets. Some pockets have curling edges; there are very few metal scraps in the B-side cage pockets, squeezing marks and running The wear marks are lighter.

2. Analysis of the reasons leading to the failure of FAG spherical roller bearings under eccentric load

(1) If FAG spherical roller bearings are subjected to a large axial load during installation and use, the single-sided raceway will carry a large load, which will easily cause bearing jams, inflexible rotation, and inability to adjust the center. FAG bearing failed.

(2) The A-side raceway of the outer ring and inner ring of this FAG spherical roller bearing peeled off and rolled seriously, and the inner ring peeled off from the A-side outer rib along the axial direction inward, and the A-side roller rolling surface also exists Peeling, abrasion marks, and serious rolling of the cage on this side indicate that the bearing has received a large axial load during use, resulting in an unbalanced load on the bearing. One side of the raceway has a larger load, and the other side has a smaller load. , The centering cannot be carried out, causing fatigue peeling of the raceway on the side A of the bearing ring and the working surface of the roller on this side, which will eventually lead to bearing failure.

(3) It can be seen from the axially equidistant fretting corrosion marks on the inner diameter surface of the FAG bearing inner ring that the bearing vibrates greatly during operation or the mating surface with the spindle is not close enough, the contact surface swings back and forth slightly, and the surface microprotrusion is oxidized And is worn away, causing fretting corrosion.

(4) In addition, the two quenched and tempered troostite structures of the outer ring of FAG bearings do not meet the standard requirements, indicating that the outer ring heat treatment process is improper, resulting in unqualified troostite structures and reducing the service life of FAG bearings.

(5) The spalling area is severely crushed, indicating that the FAG bearing did not stop running after it was peeled off. Continue to run for a period of time until the bearing temperature rises, and the temperature detector alarms.

3. The main reason for the failure of FAG spherical roller bearings

FAG spherical roller bearings bear a large axial load during use, which makes the single-sided raceway carry a large load, resulting in an unbalanced bearing load. The entire set of bearings cannot be aligned during operation, causing fatigue and peeling of the bearing ring raceway and roller working surface, resulting in bearing failure. This FAG spherical roller bearing has eccentric load during use, which is the main reason for the failure of FAG bearings. , Due to improper heat treatment, FAG bearing outer ring produces unqualified troostite structure, which reduces the service life of FAG bearing.