Common Causes of Ball Screw Failures
Misalignment will cause a higher than normal running torque. Check for:
- Bent Screw
- Alignment of screw in relation to journals
- Alignment of screw in relation to nut housing
- Alignment of screw in relation to slides, gibs, and roller cages
Improper lubrication can cause poor running and high wear. Check for:
- Proper maintenance of machine lubrication system
- Correct type of lubricant (follow manufacturer’s recommendations)
- Make sure lubricant is clean
- Remember synthetic lubricants can cause varnish deposits
- DO NOT USE GRAPHITE BASED LUBRICANTS
Dirty environments can cause poor running and high wear.
- Make sure proper wipers are installed and in good working condition
- Consider installing a bellow type protective cover
- Consider lubrication system filters or strainers
- Check coolants for rust and gum content
- Be careful with soaps and high pressure cleaning so that lubricants are not washed away
Store extra ball screws properly.
- Lubricate and rotate nuts periodically
- Keep screws protected with tubular plastic sheeting
- Hang ball screws vertically to keep them straight
- Keep units from excessive vibration
Be aware of the following potential problems:
- Ball screws can be overloaded
- Hardness of screw and nut may be substandard
- There may be a mismatch of leads between the screw and the nut
- A screw may have been crashed and not look like it
- A unit may be partially disassembled and not look like it
