Tolerances:
As cost is a major consideration, springs
must be produced in the most economical manner. Specified
tolerances, therefore, should be generous enough to permit
the fabrication of acceptable springs by ordinary production
methods. Also, it is wise to apply tolerances only to functional
requirements and dimensions. This practice gives the spring
maker an opportunity to make adjustments to make compensate
for the allowable variations present in the size and mechanical
properties of all spring materials. Another recommendation
for the product designers: If the standard drawing forms
have tolerance boxes for machined dimensions they are almost
sure to be impractical for springs. Delete them and apply
realistic tolerances to the mandatory spring requirements.
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Disc Spring Tolerances:
The following maximum deviations are
laid down in DIN 2093. They are valid for all Disc
Springs as per the DIN and our works standards.
In general IIS also applies these tolerances to special
sizes, however, if they deviate greatly from the DIN,
wider tolerances must be specified.
This applies to our ball-bearing Disc Springs. If closer
tolerances are required than those tolerances in DIN
2093, please consult us.
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Thickness
Tolerances
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| Group |
t
or t' (mm) |
Tolerance
for t (mm) |
| 1 |
0.2
to 0.6
>0.6 to <1.25 |
+0.02/-0.06
+0.03/-0.09 |
| 2 |
1.25
to 3.8
>3.8 to 6.0 |
+0.04/-0.12
+0.05/-0.15 |
| 3 |
>6.0
to 14.0 |
+0.10/-0.10 |
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| Free Height
Tolerances |
| Group |
t |
Tolerance
for t (mm) |
| 1 |
<1.25 |
+0.10/-0.05
+0.03/-0.09 |
| 2 |
1.25
to 2.0
>2.0 to 3.0
>3.0 to 6.0 |
+0.15/-0.08
+0.20/-0.10
+0.30/-0.15 |
| 3 |
>6.0
to 14.0 |
+0.30/-0.30 |
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Load
Tolerances
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The
static load F must be determined at the proof test height
of the Disc Spring. Calculation must be based upon
the nominal material thickness of the Disc Spring t and
not with the reduced material thickness t' . Measurements
must be made during loading of the Disc Spring.
The loading plates must be hardened, ground & polished.
appropriate lubrication must be used during the testing
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| The tolerances
on spring load |
| Group |
t |
Tolerance
for t (mm) |
| 1 |
<1.25 |
+0.25.0
- 7.5 |
| 2 |
1.25
to 3.0 |
+0.15 |
| >3.0
to 6.0 |
-
7.5 |
| 3 |
>6.0
to 14.0 |
+
5.0 |
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| To ensure
the specified spring forces, DIN 2093 allows the overall
height tolerance to be slightly exceeded. |
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| Theoretical
vs Measured Characteristic of a Disc Spring |
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The characteristic of the individual Disc Spring is non-linear.
Its shape depends on the ratio ho/t. At the lower
portion of the deflection range the characteristic in
practice depart slightly from the theoretical. When
S/ho>0.75 the characteristic in practice again departs
increasingly from the theoretical because the Disc Springs
roll upon one another or upon the supporting surface and
this leads to a continuous shortening of the lever arm.
For this reason, the spring force is only indicated at
Ss=0.75 ho in DIN 2093.
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