When an assembly isn’t performing as it should be, it can be frustrating. If a ball screw is malfunctioning, there are several paths to take to solve the problem. Is ball screw repair the right option, or should the ball screw be replaced? Each process has its benefits and downsides, and certain organizations may find that one makes more sense for their usage over the other.
Assessing the Damage
Most often, there is visual damage to the ball screw that will alert you to the problem, such as cracks, dents, or a physical break in the screw. Other times, there may be a decrease in performance. If the screw is worn out, the backlash will increase and efficiency will decrease, requiring additional torque or horsepower to turn. If the ball screw is worn out, the lead accuracy, which is critical for positioning systems, could be worse than required.
Ball Screw Repair
The benefits of a ball screw rebuild are numerous. Repairing the ball screw offers a quick turnaround time, a more cost-effective solution, and no reverse engineering. However, there are several factors to consider when analyzing if ball screw repair will be the best choice for your assembly.
A great applicant for a ball screw rebuild is a screw used in an excessively dirty application, or a ball screw with excessive backlash. In these situations, The PST Group can disassemble, clean, inspect, and rebuild the assembly with new ball bearings to the customer’s requirements, as long as there is no damage to the components.
A great example of a PST customer that utilizes rebuilt ball screws is a business that machines ceramics for a dental industry. The ceramic dust they work with is so fine that it is able to enter the ballnut and cause the ball screw assemblies to perform inadequately. To address this problem, The PST Group presented two options:
- Replace with new ball screw assemblies when needed
- Ship the units to PST to be cleaned, inspected, repaired, and shipped back for reuse.
Because the ball screw assemblies could easily be cleaned, providing a more cost-effective solution, the customer chose option two. Today, they have a rotation of ball screw assemblies that they use in their machines. When the machine isn’t performing as required, the customer will send the dirty assembly to PST, which will be cleaned and returned to the customer. In the meantime, PST had already prepped and sent back additional ball screw assemblies, which would be replaced in to the dirty assembly, reducing downtime.
Ball Screw Replacement
In certain situations, when ball screw repair is not an option, the focus shifts to ball screw replacement.
If a screw or nut have a catastrophic failure, such as a physical break, crack, or deformation, a ball screw rebuild is not possible. In addition, rebuilt ball screws are more likely to wear out quickly due to material fatigue and sizing issues, so when failure can be incredibly costly, ball screw assemblies should always be replaced to limit the risk of failure.
However, new ball screw assemblies come at an additional cost. Repaired ball screws are almost always more cost-effective, especially if drawings aren’t available and the ball screw assemblies need to be reverse engineered.
But for certain PST customers, providing new ball screws is the most efficient solution. Take, for example, a customer that approached PST after their machine went down. The process of tearing the machine down to access the damaged ball screw was cumbersome and costly, so the decision was made to replace the ball screw entirely. The new ball screw provided the customer the confidence and performance to run the piece of equipment for a long time without downtime.
Which method is right for you?
No matter your assembly or needs, the PST team can help you assess the situation and decide on an appropriate course of action. Contact an expert today.
