Depending on their specific condition, ball screws are often repairable. Certain issues, including loss of repeatability can be solved through regrinding the grooves of the ball thread and subsequently using larger balls in the entire assembly. If a ball sustains minor damage, it can generally be straightened and returned to service with its original intended accuracy. Ball screw repair can also fix problems such as chipping, brinelling, spalling, and feathering through re-plating and regrinding. At Comptrol, we provide these range of repair services for ball screws.
Levels of Repair
It can take several days to inspect and evaluate a ball screw, depending on the type of repair required. Several types of common cost-effective repairs are generally available. Any one of these types of ball screw repairs will be less than the cost of a new ball screw assembly.
Regardless of the type or repair, the steps involved are basically the same. They include: inspecting, Evaluation, Repair necessary parts, cleaning, re-balling, and possibly straightening.
A level I repair can take care of the common problem of loss of repeatability resulting from wear. During the repair process, new larger balls are added at each level to restore repeatability and preload. In addition, the screw is also straightened.
A level II repair includes steps taken in level I and adds regrinding of the ball nut.
A level III repair includes the previous repair steps plus regrinding of the ball screw threads and rebuilding of the journal diameters. This is combined with eutectic spraying and the process of grinding them down to the appropriate size.
A level IV repair includes the repairs mentioned above plus regrinding of the ball screw and the ball nut. This type of repair may cost a little more than half of the price of a new ball screw assembly. This repair is worth it since it will produce a repaired assembly that has a normal service life. In some more complex ballscrew assemblies, the ballscrew may need replaced.
When the cost of repair reaches about two-thirds of buying a new assembly, it is recommended to buy a new assembly.
It should be noted that other contingencies can occur that alter or increase the required repairs mentioned above.