Damage Condition

The raceways of the screw shaft and ball nut and/or the surface of the ball peel off like scales because of fatigue.

Possible Causes Natural life of the ball screw Improper assembly (misalignment) Insufficient lubrication or inadequate lubricant Developed from indentations or corrosion pits Intrusion of contamination and/or water Countermeasures If the rolling fatigue life is shorter than expected, review the size of the ball screw Improve assembly accuracy Improve the way of lubrication Select an adequate lubricant Avoid impact load to the ball screw Improve sealing capability of the ball screw

Flaking 1

Part: Screw shaft
Symptom: The surface of the ball peels off like scales
Cause: Excessive offset load to a ball nut initiated by misaligned ball screw shaft

Flaking 2

Part: Ball nut
Symptom: The surface of the ball peels off like scales
Cause: Excessive offset load to a ball nut initiated by misaligned ball screw shaft

Source: NSK