Free Length Tolerances
Free Length Tolerances
(OP)
How would one go about calculating the free length tolerance on the following spring?
d = .016"
OD = .292"
Lf = 1.2"
Ntotal = 20
Material = Phos. Bronze
Standard equations I have seen come out with tol. bigger than the free length! Are there any equations that practically take into account large spring indices and low spring rates?
I would appreciate some opinions or experience in this area.
Thanks, Jack
d = .016"
OD = .292"
Lf = 1.2"
Ntotal = 20
Material = Phos. Bronze
Standard equations I have seen come out with tol. bigger than the free length! Are there any equations that practically take into account large spring indices and low spring rates?
I would appreciate some opinions or experience in this area.
Thanks, Jack





RE: Free Length Tolerances
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RE: Free Length Tolerances
RE: Free Length Tolerances
RE: Free Length Tolerances
RE: Free Length Tolerances
Working from BS1726 I have two formula for tolerance on free length thus:-
(Lo + 10mm)*(c+25mm)/(2000) = tol on free length
this is for group A type springs
where Lo = free length in mm
c = spring index
For group B type springs use the same formula as above and multiply the answer by 1.2
so for your spring index is 17.25
free length is 1.2" = 1.2 * 25.4 = 30.48mm
using the formula for group A tol on length is 0.855mm
for goup B springs tol on length = 0.855mm * 1.2 = 1.026mm
The group A and B springs are just for different tolerances
classes of springs and obviously from above group A springs are made to tighter tolerances than group b springs.
Hope this helps
regards desertfox
RE: Free Length Tolerances
RE: Free Length Tolerances
Thanks, Jackpot