An academic question about circlips

[todd281]

There is a fine line between lazy and smart enough not to reinvent the wheel. I also happen to believe that the only stupid questions are the ones never asked. I just thought that there might be a simplified chart or graph on the subject.

 

[pontiac428]

Since you're shopping for answers, the DIN 471 standard I cited includes this handy chart of sizes and strengths of circlips. Here is a table of circlip strengths taken from that standard;

Circlips External - Roy Mech

roymech.org

and here is a step by step for calculating your own result:

https://www.rotorclip.com/images/wysiwyg_images/library/LoadCapacityArticle8_10.pdf

and here's a whole dang booklet written to answer your question specifically:

https://www.rotorclip.com/downloads/UltimateRetainingRingGuide.pdf

So, yes, the answer is out there, and if you look for it, it has a way of coming into focus.

 

[j-becker]

Thanks for the great info in this thread -- I always learn something interesting when browsing the forum. The interesting observation in the DIN table is that the groove seems to be generally weaker than the circlip, especially for the smaller diameters. Reason could be at least partially due to the assumption of only 200N/mm2 yield strength for the steel which is low even for mild steel and about half of standard ST37 / 1018. I wonder whether it includes a safety factor. Hard to tell without access to the full DIN.

 

[pontiac428]

I wonder whether it includes a safety factor. Hard to tell without access to the full DIN.

Here is an older copy of the DIN standard, still very informational.

I think the reason you are getting different results for the shaft vs the ring is there are different moduli to use for tensile vs. shear vs. plastic deformation. It looks like you have tensile values. The clip is a shear function and the shaft/groove is a plastic function.

 

[j-becker]

Here is an older copy of the DIN standard, still very informational.

I think the reason you are getting different results for the shaft vs the ring is there are different moduli to use for tensile vs. shear vs. plastic deformation. It looks like you have tensile values. The clip is a shear function and the shaft/groove is a plastic function.

Thanks a lot! That was really going a long way in satisfying my curiosity. There is no explicit safety factor assumed but the assumptions for normal steel is low (and they say in 7.1 that is proportionally higher for steels with higher yield strength). The assumption of spring steel for the circlip (C65/1065 or better) explains the majority of the difference in the load bearing capacity between groove and clip in table 1. Of course, when the groove is significantly chamfered or rounded, the failure mode for the clip is buckling out (hence adjusting for the modulus of materials other than steel in 7.2).