Concentricity of tolerance rings.

[moon161]

I'm doing a tolerance stackup of an assembly with tolerance rings to fit bearings in a bores, one manufacturer is here:

https://usatolerancerings.com/

Does anyone have experience with how much they affect the conecentricity of the bearing with the bore?

TIA

 

[3DDave]

You would have to ask them or any other maker, but I would expect that it's not much. They will be embossed from the flat condition and then rolled, so each bump should be suitably uniform and just offset the original bore. However, if one is looking for extremely small variation limits then an item that intentionally deforms might not be a great choice.

From their web site:

Will a tolerance ring keep components centered?

In most cases, the tolerance ring should maintain about 0.0008” concentricity for components up to 2” in diameter. The concentricity is also dependent on how accurate the center axes of the components (i.e., shaft, housing bore) were made.

I also expect that side load will change the concentricity, an expected outcome from a device designed to lower the stiffness of the joint.

 

[EdStainless]

They are meant to be compliant enough so that your overall assembly will control things.

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P.E. Metallurgy, consulting work welcomed

 

[moon161]

Good catch 3Dave, thanks!

8 tenths will suit me fine.

 

[moon161]

Thanks Ed,

In this case it's a bit of a concern because the far end of the shaft is floating.

 

[EdStainless]

If the far end of the shaft is floating, then the last bearing should be rigid.
You use these most often when you as series of bearings (either parallel or axial) to prevent binding because of very minor misalignment.


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P.E. Metallurgy, consulting work welcomed

 

[Tmoose]

"the far end of the shaft is floating."

I don't think I'm PICTURE-ing that correctly.

 

[moon161]

Unsupported. There's an impeller on it in a pump casing. Thrust bearing near one end, another bearing near the middle, impeller on the far end. Everyday centrifugal pump.