Fretting Corrosion Causes and Countermeasures

Fretting Corrosion:

1. A special wear process that occurs at the contact area between raceways and balls under load or impact and in the presence of repeated relative surface motion load, resulting in lubricant failed (as shown below).

Possible Causes of Fretting Corrosion:

1. It is difficult to prevent the rotor's axial and rotary motion which results in the bearing cyclic motion in small displacement.
2. Abnormal motion between balls and raceway due to the environmental vibration while stationary.

Fretting Wear Process:

1. Axial wear occurs on raceways.

   Lighter

   

   Inner Ring

   

   

   Inner Ring(x80)

   More Serious

   

   Inner Ring

   

   

   Outer Ring

2. Wear Process: (1) Slight reciprocating movement cause contact area in boundary friction. (2) At the contact areas, lubricant is squeezed out and not al lowed to be replenished, resulting in metal-to-metal contact. Slight lubricant and friction points form a nearly closed space. (3) Lubricant in this closed space constantly absorbs the heat from boundary friction and evolves acid corrosion, resul ting in raceways and ball surface corrosion and oxidation.

Countermeasures:

1. Enhance the strength of package.
2. Choose anti-fretting grease.
3. Apply appropriate axial preload.