The DIN 2093 specification classifies disc springs into three groups:
Group 1:- Under 1.25mm thick
Cold formed – Radiused edges – Without bearing flats
Estimated Group 1 Fatigue Life
Group 2:- 1.25mm thick up to and including 6mm
Cold formed machined (or “fine blanked”) – Radiused edges – Without bearing flats
Estimated Group 2 Fatigue Life
Group 3:- Above 6mm thick
Fully machined from forged blanks – With bearing flats and thickness reduced
Estimated Group 3 Fatigue Life
Disc springs, in excess of 6mm thickness, have larger diametral clearances.
To minimise the possibility of bearing point misalignment when disc springs are stacked in series i.e. “back-to-back”, flats are machined on the upper inside and lower outside diameter edges. The introduction of this bearing flat also moves the position of the points of contact, thus reducing the effective radial width of the disc spring and increasing its stiffness.
To ensure that disc springs with bearing flats have similar characteristics to the same size disc springs without flats, the nominal thickness is reduced (see table below).
|Thickness t’||t x 0.94||t x 0.94||t x 0.96|
Given that the overall height of a disc spring with or without bearing flats is the same, the cone height of the disc spring with bearing flats will be greater by the amount of the thickness reduction.
NOTE: The catalogued cone height dimensions (ho) do not include the appropriate increase for those disc springs in excess of 6mm thickness, which incorporate bearing flats.
|Name||Outisde dia (mm)||Inner dia (mm)||Thick (mm)||Red. Thick. (mm)||Cone Ht (mm)||Total Ht (mm)||Thick Ratio||Wt per 1000 pcs||(mm)||Force N||Stress δII N/mm||Stress δIII N/mm||(mm)||Force N||Stress δII N/mm||Stress δIII N/mm||(mm)||Force N||Stress δII N/mm||Stress δIII N/mm||(mm)||Force N||Stress δII N/mm||Stress δIII N/mm||(mm)||Force N||Stress δII N/mm||Stress δIII N/mm||(mm)||Force N||Stress δII N/mm||Stress δIII N/mm||hf:att:pa_outside-dia||hf:att:pa_inner-dia||hf:att:pa_thick||hf:att:pa_red-thick||hf:att:pa_cone-ht||hf:att:pa_total-ht||hf:att:pa_thick-ratio||hf:att:pa_wt-per-1000|