spring tolerances 3

[gregwing]

Does anyone know the tolerances that can be held on the rate of a spring? I am free to design around a compression, extension, or torsion spring - the important aspect will be how linear the rate is. I have searched around and found that stock springs appear to have a 10% tolerance on k, but nobody posts what the actually rate may be at any point in the springs deflection. Thank you.

 

[desertfox]

Hi gregwing

Normally if you are designing on a spring rate the rate is specified by the designer usually between 15% and 85% of its
full deflection range. Bear in mind also the std spring rate
formula is only valid for a pitch angle of less than 15 degrees or a deflection per turn is less than a 1/4 of mean
diameter of spring.
The reason that the rate is specified between 15 and 85% is
that the spring characteristics are non linear outside these
figures. So between these figures springs are usually very linear irrespective of the rate tolerance.
If you can provide more information about the spring and its application I may be able to help further.

regards desertfox

 

[TVP]

In general, + 10% on rate is common. + 5% is achievable by good spring manufacturers.