Disc springs

This document specifies two different grades of disc springs. Grade A defines basic requirements of disc springs for static applications with low and moderate performance. Springs manufactured according to Grade A are not used for dynamic applications. Grade B defines requirements on disc springs especially used for dynamic applications and high performance static applications. Disc springs according to Grade B ensure a better quality by higher demands on manufacturing processes and tolerance requirements. Grade B includes graphs showing the guaranteed fatigue life such as a function of stress.

Ressorts à disques

General Information

Status
Published
Publication Date
19-Sep-2018
Technical Committee
Drafting Committee
Current Stage
6060 - International Standard published
Start Date
02-Sep-2018
Completion Date
20-Sep-2018
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INTERNATIONAL ISO
STANDARD 19690-2
First edition
2018-09
Disc springs —
Part 2:
Technical specifications
Ressorts à disques —
Partie 2: Spécifications techniques
Reference number
ISO 19690-2:2018(E)
ISO 2018
---------------------- Page: 1 ----------------------
ISO 19690-2:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2018

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

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Published in Switzerland
ii © ISO 2018 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 19690-2:2018(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 2

4 Symbols and units ............................................................................................................................................................................................... 2

5 Dimensions and designation ................................................................................................................................................................... 3

5.1 General ........................................................................................................................................................................................................... 3

5.2 Disc spring groups ............................................................................................................................................................................... 5

5.3 Dimensional series .............................................................................................................................................................................. 5

6 Grade A — Basic performance requirements for static applications ............................................................5

6.1 Material ......................................................................................................................................................................................................... 5

6.2 Manufacturing process..................................................................................................................................................................... 5

6.3 Permissible stresses ........................................................................................................................................................................... 6

6.4 Presetting ..................................................................................................................................................................................................... 6

6.5 Surface condition and corrosion protection .................................................................................................................. 6

6.6 Tolerances ................................................................................................................................................................................................... 7

6.6.1 Thickness ................................................................................................................................................................................ 7

6.6.2 External- internal diameter and coaxiality ............................................................................................... 7

6.6.3 Free height............................................................................................................................................................................. 8

6.6.4 Spring load ............................................................................................................................................................................ 8

6.7 Clearance between disc spring and guiding element ............................................................................................ 8

6.8 Hardness ....................................................................................................................................................................................................... 9

6.9 Appearance ................................................................................................................................................................................................ 9

7 Grade B — Requirements on disc springs for dynamic applications and high-

performance static applications .......................................................................................................................................................... 9

7.1 Material ......................................................................................................................................................................................................... 9

7.2 Manufacturing process..................................................................................................................................................................... 9

7.3 Permissible stresses ........................................................................................................................................................................11

7.3.1 Static load ............................................................................................................................................................................11

7.3.2 Dynamic loading............................................................................................................................................................11

7.4 Shot peening ...........................................................................................................................................................................................14

7.5 Presetting ..................................................................................................................................................................................................14

7.6 Creep and relaxation .......................................................................................................................................................................14

7.7 Surface condition and corrosion protection ...............................................................................................................16

7.8 Tolerances ................................................................................................................................................................................................17

7.8.1 Thickness .............................................................................................................................................................................17

7.8.2 External-internal diameter and coaxiality..............................................................................................17

7.8.3 Free height..........................................................................................................................................................................18

7.8.4 Spring load .........................................................................................................................................................................18

7.9 Clearance between disc spring and guiding element .........................................................................................19

7.10 Hardness ....................................................................................................................................................................................................19

7.11 Appearance .............................................................................................................................................................................................19

Annex A (informative) Spring dimensions ..................................................................................................................................................20

Annex B (informative) Testing .................................................................................................................................................................................25

Annex C (normative) Representative material grades....................................................................................................................28

Bibliography .............................................................................................................................................................................................................................29

© ISO 2018 – All rights reserved iii
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ISO 19690-2:2018(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see the following

URL: www .iso .org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 227, Springs.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/members .html.
A list of all parts in the ISO 19690 series can be found on the ISO website.
iv © ISO 2018 – All rights reserved
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INTERNATIONAL STANDARD ISO 19690-2:2018(E)
Disc springs —
Part 2:
Technical specifications
1 Scope
This document specifies two different grades of disc springs.

Grade A defines basic requirements of disc springs for static applications with low and moderate

performance. Springs manufactured according to Grade A are not used for dynamic applications.

Grade B defines requirements on disc springs especially used for dynamic applications and high

performance static applications. Disc springs according to Grade B ensure a better quality by higher

demands on manufacturing processes and tolerance requirements. Grade B includes graphs showing

the guaranteed fatigue life such as a function of stress.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 683-1, Heat-treatable steels, alloy steels and free-cutting steels — Part 1: Non-alloy steels for quenching

and tempering

ISO 683-2, Heat-treatable steels, alloy steels and free-cutting steels — Part 2: Alloy steels for quenching and

tempering
ISO 6507 (all parts), Metallic materials — Vickers hardness test
ISO 6508 (all parts), Metallic materials — Rockwell hardness test
ISO 16249, Springs — Symbols
ISO 26909, Springs — Vocabulary
EN 1654, Copper and copper alloys — Strip for springs and connectors

EN 10083-1, Quenched and tempered steels — Technical delivery conditions for special steels

EN 10083-2, Quenched and tempered steels — Technical delivery conditions for unalloyed quality steels

EN 10083-3, Quenched and tempered steels — Technical delivery conditions for boron steels

EN 10089, Hot-rolled steels for quenched and tempered springs — Technical delivery conditions

EN 10132-4, Cold-rolled narrow steel strip for heat treatment — Technical delivery conditions — Part 4:

Spring steels and other applications
EN 10151, Stainless steel strip for springs — Technical delivery conditions
JIS G 3311, Cold-rolled special steel strip
JIS G 4801, Spring steels
© ISO 2018 – All rights reserved 1
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ISO 19690-2:2018(E)
JIS G 4802, Cold-rolled steel strip for springs

ASTM A240, Standard specification for chromium and chromium-nickel stainless steel plate, sheet, and

strip for pressure vessels and for general applications
ASTM A332, Specification for nickel-chromium-molybdenum steel bars for springs

ASTM A506, Standard specification for alloy and structural alloy steel, sheet and strip, hot-rolled and

cold-rolled

ASTM A568, Standard specification for steel, sheet, carbon, structural, and high-strength, low-alloy, hot-

rolled and cold-rolled, General requirements for

ASTM A666, Standard specification for annealed or cold-worked austenitic stainless steel sheet, strip, plate,

and flat bar

ASTM A682, Standard specification for steel, strip, high carbon, cold rolled, General requirements for

ASTM A684, Standard specification for steel, strip, high carbon, cold rolled
ASTM A689, Standard specification for carbon and alloy steel bars for springs

ASTM A693, Standard specification for precipitation-hardening stainless and heat-resistant steel plate,

sheet, and strip

ASTM B103, Standard specification for phosphor bronze pate, sheet, strip, and rolled bar

ASTM B194, Standard specification for copper-beryllium alloy plate, sheet, strip, and rolled bar

ASTM B196, Standard specification for copper-beryllium alloy rod and bar
GB/T 1222, Spring steels

BS 970-2, Specification for wrought steels for mechanical and allied engineering purposes: Requirements

for steels for the manufacture of hot-formed springs
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 26909 apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
4 Symbols and units

For the purposes of this document, the symbols and units given in ISO 16249, Table 1 and Figure 1 apply.

Table 1 — Symbols and units for design calculation
Symbol Unit Parameter
b mm width of scar (see Figure 2)
D mm external diameter of spring
D mm diameter of centre of rotation
d mm internal diameter of spring
NOTE 1 N/mm = 1 MPa.
r is not chamfered unless otherwise agreed between customer and supplier.
2 © ISO 2018 – All rights reserved
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ISO 19690-2:2018(E)
Table 1 (continued)
Symbol Unit Parameter
modulus of elasticity of material (carbon steel and carbon alloy steel:
E N/mm
206 000 N/mm )
F N spring load
F N design spring load when spring is in the flattened position
F N spring load at the time of combining springs
F N spring test load at H
t t
H mm height of spring when measuring spring test load, H = H – 0,75h
t t 0 0
H mm free height of spring
h mm clean cut (see Figure 2)
h mm initial cone height of spring without flat bearings, h = H – t
0 0 0
h , mm initial cone height of spring with flat bearings, h , = H – t
0 f 0 f 0 f
i — number of springs combined in series
L mm free height at the time of combining springs
N — number of cycles for fatigue life
n — number of springs piled in parallel

OM — point at upper surface of the spring perpendicular to the centre line at point P

P — theoretical centre of rotation of disc cross section
R N/mm spring rate
r mm radius at edge
s mm deflection of spring
s mm deflection of stack
s mm deflection of spring preloaded
t mm thickness of spring
t mm reduced thickness of single disc spring with flat bearings
V mm length of lever arms
V mm length of lever arms with flat bearings
ΔF N spring load loss
Δh mm initial cone height loss of spring
ν — Poisson’s ratio of material
σ N/mm alternative stress, σ = σ – σ
H H max min
σ N/mm stress at position OM
σ N/mm maximum fatigue stress
max
σ N/mm minimum fatigue stress
min
σ N/mm stress at position I
σ N/mm stress at position II
σ N/mm stress at position III
III
σ N/mm stress at position IV
NOTE 1 N/mm = 1 MPa.
r is not chamfered unless otherwise agreed between customer and supplier.
5 Dimensions and designation
5.1 General

Figure 1 illustrates a single disc spring, including the relevant positions of loading.

© ISO 2018 – All rights reserved 3
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ISO 19690-2:2018(E)
a) Without flat bearings — Group 1 and Group 2
b) With flat bearings — Group 3
Key
D external diameter of spring
D diameter of centre of rotation
d internal diameter of spring
F spring load
H free height of spring

OM point at upper surface of the spring perpendicular to the centre line at point P

P theoretical centre of rotation of disc cross section
r radius at edge
t thickness of spring
t reduced thickness of single disc spring with flat bearings
V length of lever arms
V length of lever arms with flat bearings
I position I
II position II
III position III
IV position IV
r is not chamfered unless otherwise agreed between customer and supplier.

Figure 1 — Single disc spring (sectional view), including the relevant positions of loading

4 © ISO 2018 – All rights reserved
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ISO 19690-2:2018(E)
5.2 Disc spring groups
Table 2 shows the disc spring groups.
Table 2 — Disc spring groups
Group t With flat bearings and reduced thickness
1 0,2 ≤ t < 1,25 No
2 1,25 ≤ t ≤ 6,0 No
3 6,0 < t ≤ 14,0 Yes
5.3 Dimensional series
Table 3 shows the dimensional series.
Table 3 — Dimensional series
Dimensional series h /t t /t D/t
0 f
A ≈ 0,40 ≈ 0,94 ≈ 18
B ≈ 0,75 ≈ 0,94 ≈ 28
C ≈ 1,30 ≈ 0,96 ≈ 40
NOTE Refer to Annex A for typical disc spring dimensions.
6 Grade A — Basic performance requirements for static applications
6.1 Material

Unless otherwise agreed between customer and supplier, disc springs should be made from material

conforming to Table 4.
6.2 Manufacturing process

Unless otherwise agreed between customer and supplier, disc springs should be made by the

manufacturing process shown in Table 4.
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ISO 19690-2:2018(E)
Table 4 — Manufacturing process and material
Group Manufacturing process Material
Stamping,
Carbon steel
1 0,2 ≤ t < 1,25 cold or hot forming,
or alloy steel
edge rounding
Stamping,
cold or hot forming, Carbon steel
2 1,25 ≤ t ≤ 6,0
D and d turning , or alloy steel
edge rounding
Cold or hot forming,
turning on all sides,
edge rounding
3 6,0 < t ≤ 14,0 Alloy steel
Stamping ,
cold or hot forming,
D and d turning,
edge rounding
D and d turning are optional.
Carbon steel used 1,25 ≤ t ≤ 2,0 only.
Stamping without D and d turning is not permitted.
6.3 Permissible stresses

For disc springs made of steels according to materials shown in Table 4, which are subject to static

loading, the design stress, σ , at maximum deflection shall not exceed 1 400 N/mm .

NOTE The design stress, σ , is derived from the formulae given in ISO 19690-1.
6.4 Presetting

After heat treatment, each disc spring shall be loaded until it is in the flat position. After loading the

disc spring with twice its spring test load, F , the tolerances for the spring load as specified in Table 8

shall be met.
6.5 Surface condition and corrosion protection
The surface treatment should be agreed between customer and supplier.
The surface shall be free from defects such as scars, cracks and corrosion.

As disc springs are easy to be rusted, it is preferable to apply suitable corrosion protection to them.

Whether and which corrosion protection is to be provided shall depend on the particular spring

application. Suitable corrosion protections include phosphating, black finishing and the application of

protective metallic coatings such as zinc or nickel. This shall be agreed between customer and supplier.

It is possible that the galvanizing processes using aqueous solutions that are currently available do

not preclude the risk of hydrogen embrittlement. Disc springs with a hardness exceeding 40 HRC are

more prone to the risk of hydrogen embrittlement than softer springs. Special care shall therefore

be taken when selecting the material, manufacturing process, heat treatment and surface treatment.

When ordering disc springs with galvanic surface protection, it is advisable to consult the spring

manufacturer.
For disc springs, galvanic surface protection should be avoided.
Phosphating and oiling form the standard corrosion protection for disc springs.
6 © ISO 2018 – All rights reserved
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ISO 19690-2:2018(E)
6.6 Tolerances
6.6.1 Thickness
The tolerances on thickness are shown in Table 5.
For information on testing of thickness, see Annex B.
Table 5 — Tolerances on thickness
Dimensions in mm
Group t Tolerance
+00, 3
0,2 ≤ t ≤ 0,6
−00, 6
+00, 6
0,6 < t < 1,25
−00, 9
+00, 9
1,25 ≤ t ≤ 3,8
−01, 2
+01, 0
3,8 < t ≤ 6,0
−01, 5
3 6,0 < t ≤ 14,0 ±0,15
6.6.2 External- internal diameter and coaxiality

The tolerances on external diameter and internal diameter are shown in Table 6. The tolerances are

determined by the tolerance grade IT13, which is specified in ISO 286-2.
Coaxiality tolerance: 2 × IT13

For information on testing of external diameter and internal diameter, see Annex B.

Table 6 — Tolerances on external diameter and internal diameter
Dimensions in mm
D or d Tolerance, D Tolerance, d
0 +01, 8
over 3 up to 6
−01, 8
0 +02, 2
over 6 up to 10
−02, 2
0 +02, 7
over 10 up to 18
−02, 7
0 +03, 3
over 18 up to 30
−03, 3
0 +03, 9
over 30 up to 50
−03, 9
0 +04, 6
over 50 up to 80
−04, 6
0 +05, 4
over 80 up to 120
−05, 4
0 +06, 3
over 120 up to 180
−06, 3
0 +07, 2
over 180 up to 250
−07, 2
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ISO 19690-2:2018(E)
6.6.3 Free height
The tolerances on free height are shown in Table 7.
For information on testing of free height, see Annex B.
Table 7 — Tolerances on free height
Dimensions in mm
Group t Tolerance
+01, 0
0,2 ≤ t < 1,25
−00, 5
+01, 5
1,25 ≤ t < 2,1
−00, 8
+02, 0
2 2,1 ≤ t < 3,5
−01, 0
+03, 0
3,5 ≤ t ≤ 6,0
−01, 5
3 6,0 < t ≤ 14,0 ±0,30
6.6.4 Spring load

The spring load, F shall be determined at test height H = H – 0,75h . The tolerances on spring loads

t, t 0 0

are shown in Table 8. The measurement is taken while loading between flat plates, using a suitable

lubricant. The flat plates shall be hardened, ground and polished. In the case of stacking the springs, the

tolerance on spring load should be agreed between customer and supplier.

To comply with the specified load tolerances, it can be necessary to exceed the tolerance values specified

for H and t.
Table 8 — Tolerances on spring load
Tolerance
F (H = H – 0,75h )
Group t t 0 0
mm N
+30%
0,2 ≤ t < 1,25
−10%
+20%
1,25 ≤ t ≤ 3,0
−10%
+15%
3,0 < t ≤ 6,0
−75, %
3 6,0 < t ≤ 14,0 ±10 %
6.7 Clearance between disc spring and guiding element

A guiding element is necessary to keep the disc spring in position. This should preferably be a mandrel.

In the case of external positioning, a sleeve is preferred.
Table 9 shows clearance of guide.
8 © ISO 2018 – All rights reserved
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ISO 19690-2:2018(E)
Table 9 — Clearance of guide
Dimensions in mm
D or d Clearance of diameter
up to 15 0,2
over 15 up to 20 0,3
over 20 up to 26 0,4
over 26 up to 31,5 0,5
over 31,5 up to 45 0,6
over 45 up to 75 0,8
over 75 up to 140 1,0
over 140 up to 250 1,6
6.8 Hardness
The hardness of disc springs shall lie within the range of 42 HRC to 52 HRC.

For group 1 disc springs, the hardness shall be determined according to Vickers (425 HV10 to 510 HV10).

After heat treatment, the disc spring shall not exhibit a depth of decarburization exceeding 3 % of its

thickness.

Vickers hardness testing shall be carried out according to ISO 6507 (all parts) and Rockwell hardness

testing according to ISO 6508 (all parts).
6.9 Appearance

The appearance testing should be carried out according to B.3.6. The surface shall be free from cracks,

impedimental defects, burrs, corrosion and so forth.
In addition, there shall be no sharp edge on the inner and outer circumferences.
7 Grade B — Requirements on disc springs for dynamic applications and high-
performance static applications
7.1 Material
Disc springs shall be made from material conforming to Annex C.
7.2 Manufacturing process

Disc springs shall be made in accordance with the manufacturing process shown in Table 10 and

Figure 2.
© ISO 2018 – All rights reserved 9
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ISO 19690-2:2018(E)
Table 10 — Manufacturing process and material
Group Manufacturing process Material according to Annex C
Stamping,
cold or hot forming,
edge rounding
Cold rolled carbon steel
Stamping,
or cold rolled alloy steel
cold or hot forming,
1 0,2 ≤ t < 1,25 or hot rolled if all surfaces are machined
D and d turning,
to remove scale and surface defects ac-
edge rounding
cording to Annex C
Fine blanking ,
cold or hot forming,
edge rounding
Stamping ,
cold or hot forming,
Cold rolled carbon steel
D and d turning,
or cold rolled alloy steel
edge rounding
2 1,25 ≤ t ≤ 6,0 or hot rolled if all surfaces are machined
to remove scale and surface defects ac-
Fine blanking ,
cording to Annex C
cold or hot forming,
edge rounding
Cold or hot forming,
turning on all sides,
edge rounding
Stamping , Cold rolled alloy steel
cold or hot forming, or hot rolled if all surfaces are machined
3 6,0 < t ≤ 14,0
D and d turning, to remove scale and surface defects ac-
edge rounding cording to Annex C
Fine blanking ,
cold or hot forming,
edge rounding
Stamping without D and d turning is not permitted.

Fine blanking in accordance with Figure 2: clean cut min. 75 %, b /t max. 15 %, tear off max. 25 %.

Carbon steel used 1,25 ≤ t ≤ 2,0 only.
10 © ISO 2018 – All rights reserved
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ISO 19690-2:2018(E)
Key
1 scar b width of scar
2 clean cut part b /t scar width ratio of thickness, max. 15 %
3 tear off h clean cut
h /t clean cut ratio of thickness, min. 75 %
t thickness of spring
Figure 2 — Fine blanking
7.3 Permissible stresses
7.3.1 Static load

For disc springs made of steels according to materials shown in Table 10, which are subject to high-

performance static loading or to dynamic applications, the design stress, σ , at maximum deflection

shall not exceed 1 600 N/mm .
NOTE The design stress, σ , is derived from the formulae given in ISO 19690-1.
7.3.2 Dynamic loading
Minimum initial deflection is needed to avoid cracking.

Disc springs subject to fatigue loading shall be designed and installed in such a way that the initial

deflection, s , is approximately 0,15h to 0,20h in order to avoid cracking at the upper inner edge,

1 0 0

position I (see Figure 1) as a result of residual stresses from the presetting process.

To determine the number of load cycles, first calculate the tensile stresses of σ and σ at maximum

II III
and minimum load. Calculate the number of load cycles for positions II and III.
...

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