During the use of bearings, creep corrosion occurs when there is relative movement between the bearing ring and the shaft or bearing seat. Creeping is usually caused by loose fit of bearings or inaccurate shape of bearings.
This relative movement will cause smaller material particles to peel off from the bearing surface and bearing mating surface. Once in contact with air, these particles will rapidly oxidize to form iron oxide (see figure below). The volume of iron oxide is greater than that of iron (steel). Creeping corrosion may ultimately result in uneven support force on the bearing ring, which can have adverse effects on the load distribution of the bearing.
Schematic diagram of various stages of peristaltic corrosion
The corroded area also serves as a rupture gap.
The specific symptoms of creep corrosion are rust on the outer surface of the bearing outer ring or the inner hole of the bearing inner ring. The corresponding track load traces may be abnormally obvious. In some cases, creep corrosion is actually a secondary damage caused by severe peeling of the raceway.
According to different chemical reactions, corrosion marks may present as follows:
·Red (red iron, ferric oxide)
·Black (magnet, iron oxide)
The following figure shows creep corrosion caused by improper turning or bending of the shaft surface (due to cantilever load).
Peristaltic corrosion of the inner bore caused by improper shaft neck or shaft bending
The following figure shows creep corrosion caused by excessive load or improper mating surface.
Inner ring creep corrosion caused by excessive load or improper shaft neck
In order to avoid creep corrosion of bearings or slow down the corrosion rate, on the one hand, the tolerance (fit) of bearings should be adjusted appropriately, and on the other hand, special anti creep grease or coating should be used. We do not recommend using adhesives with special formulas to prevent bearing creep corrosion.
For more customized corrosion-resistant bearing models and sizes, please contact us. Thank you.
Email: jackengineer@blhbearing.com
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