Ball Screws - Cautions

Ball screws must be lubricated to meet life requirements

• Oil or grease is required to prevent premature failure
• Reducing the coefficient of friction too much actually increases failure potential

Ball screws must be loaded axially

• Moment loads may decrease life by 90%
• Radial loads may decrease life by 90%

Ball screw misalignment  is a significant cause of failures

• Misalignment causes fatigue stress on end journals
• Misalignment induces a radial or moment load on the ball nut
• Misalignment can cause binding and increased loads
• Misalignment can cause vibration and fretting corrosion