Disc Spring Tolerance

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.

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.

Thickness Tolerances

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

Thickness 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

Load Tolerances

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

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

To ensure the specified spring forces, DIN 2093 allows the overall height tolerance to be slightly exceeded.

Theoretical vs Measured Characteristic of a Disc Spring

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.