Damage Condition

Frettings are on the raceways caused by a relative small amplitude of rubbing between mated contact surfaces. (It is also called fretting corrosion because of reddish brown or black wear particles that develop between the rubbing contact surfaces of balls and raceways.)

Possible Causes Completely dried out lubricant because of small amplitude oscillation Countermeasures Use anti-fretting grease (Application of proper lubricant) Distribute the lubricant over the contact surfaces by longer stroke motions in a certain frequency (i.e: Once every 5,000 cycles) Fretting

Part: Screw shaft
Symptom: Dried out lubricant on rolling surface
Cause: Fretting caused due to completely dried out lubricant because of small amplitude oscillation

Source: NSK