DIN 2093 is the German standard that fixes the dimensions, tolerances and reference spring forces for conical disc springs, also sold as Belleville washers, in three manufacturing groups and three dimensional series A, B and C [S1][S4]. Stock ranges commonly run from M4 to M250 bolt sizes, with outer diameters De from 8 mm to 250 mm and free heights h0 from 0.6 mm to 19.6 mm [S3][S5].
The 2026-07-10 chart published by Impex Industrial Corporation covers the stocked range M4 to M55, listing inner diameter Di, outer diameter De, material thickness t, free height h0 and computed travel to flat h0 - t for 23 sizes [S2]. The full DIN 2093 range, as tabulated by Aspen Fasteners and TorqBolt, runs to De 250 mm, Di 127 mm, t up to 14 mm, and h0 up to 19.6 mm, with 30 standard rows from Group 1 through Group 3 [S3][S5].
DIN 2093 size chart, Series A, M4 to M55
Series A is the most commonly stocked DIN 2093 geometry and is the geometry Westfield Fasteners and Impex both default to [S2][S4]. For an M10 bolt the Series A reference spring is De 20 mm, Di 10.2 mm, t 1.1 mm, h0 1.55 mm, travel to flat 0.45 mm, and a reference single-spring force F = 1530 N at deflection s = 0.34 mm [S3][S5]. For an M20 bolt the Series A row steps up to De 40 mm, Di 20.4 mm, t 2.25 mm, h0 3.15 mm, travel to flat 0.9 mm, and F = 6540 N at s = 0.68 mm [S3]. The full chart used by the trade in the M4 to M55 window has De values 8, 10, 12.5, 14, 16, 18, 20, 22.5, 25, 28, 31.5, 35.5, 40, 45, 50, 56, 63, 71, 80, 90, 100, 112, with Di running 0.2 mm to 0.4 mm over the matching bolt shank to give clearance [S2][S5].
Three manufacturing groups split at 1.25 mm and 6 mm thickness
DIN 2093 splits the range into three groups by material thickness, and the group controls how the part is made [S3][S4]. Group 1 covers t under 1.25 mm and is cold formed with radiused edges and no contact flats. Group 2 covers t from 1.25 mm up to and including 6 mm and is cold formed, then machined or fine blanked, with radiused edges and no contact flats. Group 3 covers t over 6 mm and is fully machined from forged blanks with contact flats and a reduced thickness at the bearing surfaces. In the reference table, Group 1 ends at De 22.5 mm (t 1.25 mm), Group 2 covers De 25 mm through De 100 mm, and Group 3 covers De 125 mm through De 250 mm, where the table shows reduced alternative thicknesses t' of 7.5, 9.4, 11.25 and 13.1 mm alongside the nominal t [S3][S5].
Tolerances, coaxiality, and thickness bands
Series A tolerances under DIN 2093 are h12 on outer diameter d2 and H12 on inner diameter d1 [S4]. For coaxiality, d2 at or below 50 mm is held to IT11, and d2 above 50 mm is held to IT12. Thickness tolerance depends on the thickness band: for 0.2 mm to 0.6 mm it is +0.02 / -0.06 mm; for 0.6 mm to 1.25 mm it is +0.03 / -0.09 mm; for t below 1.25 mm the free overall height tolerance is +0.10 / -0.05 mm [S4]. DIN 2093 also requires a guiding element, an internal mandrel or external sleeve, to keep stacks in place, and warns that all disc springs are subject to creep and relaxation if loaded beyond the material's permissible stresses [S4].
Series vs parallel stacking for force or travel
Disc springs are almost never used singly in bolted joints because the travel on a single spring is small, typically 0.2 mm to 2.5 mm in the M4 to M55 chart, and the force is set by one row of the table [S2]. Stacking in series, with springs alternating <><>, adds deflections while the load capacity stays that of a single spring, and is the way to get more travel. Stacking in parallel, with springs nested >>, adds load capacity at the same deflection. Most engineered stacks are a combination: parallel packs arranged in series, tuned to hit a target spring rate [S2]. For a related engineering look at pack behaviour under bolt load, see this bolt-count trade-off on disc pack joints, and for fatigue verification of a chosen stack see reading points II/III on DIN EN 16983 diagrams.
Reference forces and stresses at deflection s
The DIN 2093 table is more than a dimensional chart; each row also lists the reference single-spring force F (N) at the recommended working deflection s (mm), plus the calculated remaining travel l0 - s, and the resulting reference stresses sigma OM and sigma II in N/mm2 [S3][S5]. The pattern across Series A is consistent: F rises from 210 N at the 8 x 4.2 x 0.4 row to 48000 N at the 100 x 51 x 6 row, and to 249000 N at the 250 x 127 x 14 row, while reference stresses stay in a 1120-1460 N/mm2 band across the whole table, which is the engineering signal that Group 2 and Group 3 springs can carry very high loads without needing exotic materials [S3]. For background on what those stresses mean in service, see this encyclopedia entry on spring washers.
Materials, equivalents, and what to specify when ordering
The standard stocked execution across the sources is SS301 stainless spring steel, with ranges from M4 to M55 ex-Mumbai (Impex) and M6 to M40 (Aspen) all in 301 stainless [S2][S3]. DIN 2093 has a direct Italian equivalent, UNI 8737, for the disc spring washer geometry [S5]. When ordering, the minimum spec is the standard (DIN 2093), the size as bolt size or D x d x t, and the quantity; stacks multiply quickly and the unit of count is individual springs, not assembled joints [S2]. Series A is the default; Series B and C are alternatives Westfield supplies only on request, used when the application needs a different cone ratio h0/t than Series A delivers [S4].
When DIN 2093 is not the right pick
DIN 2093 covers only metric disc springs, so inch-dimensioned joints or ASME-pattern stacks call for a different standard. For very high temperature service above the creep limit of 301 stainless, DIN 2093 alone is not enough: the part must be ordered in a high-temperature alloy, with the standard still used for the geometry but the material specification from the engineering drawing. Working deflection is also a boundary, since the standard recommendation is to keep deflection within roughly 75% of travel to flat to preserve fatigue life, and a single spring in the M4 to M55 chart gives only 0.2 mm to 2.5 mm of travel, so any joint that needs more travel must use a stack or move to a longer-travel geometry [S2][S4].
The next thing to check on any DIN 2093 selection is the row's reference stress sigma OM against the material limit of the chosen SS301 execution; if sigma OM exceeds roughly 1300 N/mm2 in Group 2 or 1200 N/mm2 in Group 3, drop down a row or move to a parallel pack of two springs of the same size. Impex updates its stocked M4 to M55 chart periodically, with the most recent revision dated July 2026, and the full M4 to M250 reference table sits in Aspen Fasteners' DIN 2093 PDF and the TorqBolt dimensions page [S2][S3][S5].
The underlying component specifications are covered under disc coupling, and sealing washer.