Checks to be made (while the ball screw assembly is still in the machine) include:
1. Run a power check. If you show an overload condition, the ball screw may be close to permanent failure.
2. Measure the backlash between the screw and the nut.
3. Check for wipers on both ends of the nut assembly if possible. Warning signs include: Missing wipers, excessively worn brush or plastic wipers, and felt wipers in any condition. Felt wipers trap chips and grinding compounds which can cause permanent wear and failure.
4. Check the exposed screw for rust, pits, and chatter marks in the ball groove.
5. Check for heavy screw wear in areas where the nut travels the most. Compare these worn spots with areas the nut does not travel as often.
6. Make sure the lubrication system is working properly.
- Using a light oil will both lubricate and flush contaminants out of the ball nut.
- Higher lube system pressures will insure better flushing and lubrication.
- Make sure you can see the oil.
- Determine whether the oil is clear or contaminated.
- If there is not properly working lube system, remove the ball screw as soon as possible.
- This is a good time to also check the lube system for slides, ways, spindles, bearings, etc.
7. Check the ball screw alignment.
- The alignment should be within a few ten-thousandths of an inch.
- Try to determine if the screw is bent.
- Check for slide wear and slide alignment.
8. If the nut is accessible, unbolt the nut from the housing and rotate the nut.
- If the nut feels rough when turning, we suggest removing the unit before further damage occurs.
- Check for proper alignment of the nut to the housing.
- Make sure the bolts holding the nut in the housing are properly tightened.
9. If you ever find steel balls laying on the floor or in the machine, shut the machine down immediately to avoid serious damage and injury.
10. All vertically mounted ball screw assemblies and vertically mounted acme screw assemblies should be checked regularly as a normal safety procedure.
If your ball screw assembly is losing accuracy or showing signs of damage?
Contact Dynatect for a free screw repair analysis.
In addition to precision ball screw repair, we repair lead screws and acme screw assemblies.