When it comes to ball screw assembly, the smallest movements can easily impact the performance of your machinery. For this reason, it’s important that you understand how to measure ball screw backlash, as it can directly impact the precision of your assembly. If you’re not sure where to begin, start with a basic understanding of what backlash is.
What Is Backlash?
Backlash is what we describe as the excess movement or the play and lash of a nut on a screw that moves in the axial direction. It is strictly the axial free motion of the ball screw to the ball nut, and it’s not rotational.
To understand the significance of a ball screw’s backlash, take a look at this example. When backlash is specified as .001 inches, that means the nut is allowed a maximum of 0.001 inches of travel on the screw without rotating a nut or screw. As you can see, backlash is necessary to attain precise measurements.
For assemblies that require precise positioning, backlash can be imperative. But when an assembly has too much backlash, this can also cause the positioning to not be as precise as required.
How To Measure Backlash
Now that you know what backlash is, you’ll want to know how to measure it.
To measure for backlash, you’ll need to place a magnetic base indicator directly on the screw. Then, you will need to put a .0001 indicator point on the nut flange. After this, you’ll want to use a bar and press it in between the base and table in both directions. You won’t want to use too much pressure, or else you can bend the screw, or worse, leave ball marks on the screw or nut.
The Backlash Requirements for Ball Screws
Backlash is often tied to ball screws. However, recent changes have seen a rise in backlash requirements for ACME screws. This is important to note because each screw handles backlash requirements differently. In this case, we’ll be talking about ball screws specifically.
In order for a ball screw to achieve the consistent backlash it needs, the assembly must utilize a tighter lead tolerance screw. There are a few ways to do this. For one, you can consider using a low-grade ball screw that will be manufactured by thread grinding. Higher grade ball screws can also achieve the required backlash as long as they’re manufactured by thread rolling. You can also consider adjusting the ball bearing size of the nut.
What Wedin Can Do for Your Ball Screw Assembly
Is your ball screw currently experiencing too much backlash? Here at Wedin International, Inc., we are experts in all ball screw products. We can take a closer look at your assembly by performing a complete breakdown evaluation and inspecting all components. Our engineers find the problem and come up with a helpful solution for your assembly.
Our ultimate goal is to get your business back up and running. For this reason, we find it important to discuss how you can measure your ball screw backlash and how Wedin can help you find the right solution if you’re experiencing excessive backlash. If you’re dealing with other backlash issues, give us a call. We’ll help you resolve it in no time.