ISO 22705-1:2021

Springs — Measurement and test parameters — Part 1: Cold formed cylindrical helical compression springs

This document specifies the measurement and test methods for the general characteristics of cold formed helical compression springs made from round wire, excluding dynamic testing.

Ressort - Mesures et paramètres d'essai — Partie 1: Ressort hélicoïdal de compression cylindrique formé à froid

General Information

• Status: Published
• Publication Date: 25-Mar-2021
• ICS: 21.160 - Springs
• Technical Committee: ISO/TC 227 - Springs
• Drafting Committee: ISO/TC 227 - Springs
• Current Stage: 6060 - International Standard published
• Start Date: 26-Mar-2021
• Due Date: 27-Nov-2020
• Completion Date: 26-Mar-2021

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 22705-1
First edition
2021-03
Springs — Measurement and test
parameters —
Part 1:
Cold formed cylindrical helical
compression springs
Ressort - Mesures et paramètres d'essai —
Partie 1: Ressort hélicoïdal de compression cylindrique formé à froid
Reference number
ISO 22705-1:2021(E)
©
ISO 2021

---------------------- Page: 1 ----------------------
ISO 22705-1:2021(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 22705-1:2021(E)

Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and abbreviated terms . 1
3.1 Terms and definitions . 1
3.2 Symbols and abbreviated terms. 2
4 Environmental conditions . 3
5 Qualifications of the person(s) performing the work . 3
6 Geometries of guiding and supporting devices . 4
7 Measuring and testing equipment . 4
8 Measurement and test parameter for technical cold formed cylindrical
compression springs . 4
8.1 Free length (L ). 4
0
8.1.1 General. 4
8.1.2 Type of characteristic . 4
8.1.3 Measuring and/or testing equipment . 4
8.1.4 Conditions of measurement and testing . 5
8.1.5 Method of measurement and testing . 5
8.1.6 Test location on the product . 6
8.2 Outside diameter (D ) . 6
e
8.2.1 General. 6
8.2.2 Type of characteristic . 6
8.2.3 Measurement and/or testing equipment . 7
8.2.4 Conditions of measurement and testing . 7
8.2.5 Method of measurement and testing . 7
8.2.6 Test location on the product . 9
8.3 Inside diameter (D ) .10
i
8.3.1 General.10
8.3.2 Type of characteristic .10
8.3.3 Measuring and/or testing equipment .10
8.3.4 Conditions of measurement and testing .10
8.3.5 Method of measurement and testing .10
8.3.6 Test location on the product .12
8.4 Total number of coils (n ), number of active coils (n) and coil direction .13
t
8.4.1 General.13
8.4.2 Type of characteristic .13
8.4.3 Measuring and/or testing equipment .15
8.4.4 Conditions of measurement and testing .15
8.4.5 Method of measurement and testing .15
8.4.6 Test location on the product .16
8.5 Applied end coils .16
8.5.1 General.16
8.5.2 Type of characteristic .16
8.5.3 Measuring and/or testing equipment .17
8.5.4 Conditions of measurement and testing .17
8.5.5 Method of measurement and testing .17
8.5.6 Test location on the product .17
8.6 Solid length (L )/solid force (F ) .17
c c
8.6.1 General.17
8.6.2 Type of characteristics .17
8.6.3 Measuring and/or testing equipment .18
8.6.4 Conditions of measurement and testing .18
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ISO 22705-1:2021(E)

8.6.5 Method of measurement and testing .18
8.6.6 Test location on the product .19
8.7 Spring load (F) .19
8.7.1 General.19
8.7.2 Type of characteristic .19
8.7.3 Measuring and/or testing equipment .19
8.7.4 Conditions of measurement and testing .19
8.7.5 Method of measurement and testing .20
8.7.6 Test location on the product .20
8.8 Spring pitch (p)/distance between the coils .20
8.8.1 General.20
8.8.2 Type of characteristic .20
8.8.3 Measuring and/or testing equipment .21
8.8.4 Conditions of measurement and testing .21
8.8.5 Method of measurement and testing .21
8.8.6 Test location on the product .21
8.9 Ground surface/angle .21
8.9.1 General.21
8.9.2 Type of characteristic .22
8.9.3 Measuring and/or testing equipment .22
8.9.4 Conditions of measurement and testing .23
8.9.5 Method of measurement and testing .23
8.9.6 Test location on the product .23
8.10 Perpendicularity (e ) .23
1
8.10.1 General.23
8.10.2 Type of characteristic .23
8.10.3 Measuring and/or testing equipment .24
8.10.4 Conditions of measurement and testing .24
8.10.5 Method of measurement and testing .24
8.10.6 Test location on the product .25
8.11 Parallelism (e ) .25
2
8.11.1 General.25
8.11.2 Type of characteristic .25
8.11.3 Measuring and/or testing equipment .25
8.11.4 Conditions of measurement and testing .26
8.11.5 Method of measurement and testing .26
8.11.6 Test location on the product .26
8.12 Shear-off burr .26
8.12.1 General.26
8.12.2 Type of characteristic .27
8.12.3 Measuring and/or testing equipment .27
8.12.4 Conditions of measurement and testing .27
8.12.5 Method of measurement and testing .27
8.12.6 Test location on the product .28
Annex A (informative) Calculation of spring rate (R) .29
Bibliography .30
iv © ISO 2021 – All rights reserved

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ISO 22705-1:2021(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 of 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 www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 227, Springs.
A list of all parts in the ISO 22705 series can be found on the ISO website.
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.
© ISO 2021 – All rights reserved v

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INTERNATIONAL STANDARD ISO 22705-1:2021(E)
Springs — Measurement and test parameters —
Part 1:
Cold formed cylindrical helical compression springs
1 Scope
This document specifies the measurement and test methods for the general characteristics of cold
formed helical compression springs made from round wire, excluding dynamic testing.
2 Normative references
There are no normative references in this document.
3 Terms, definitions, symbols and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions 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/
3.1.1
spring
mechanical device designed to store energy when deflected and to return the equivalent amount of
energy when released
[SOURCE: ISO 26909:2009, 1.1]
3.1.2
compression spring
spring that offers resistance to a compressive force applied axially
Note 1 to entry: In the narrow sense, a compression spring indicates a helical compression spring.
[SOURCE: ISO 26909:2009, 1.2]
3.1.3
coil spring
coil-shaped spring
[SOURCE: ISO 26909:2009, 3.11]
3.1.4
helical compression spring
compression spring made of wire of circular cross-section, wound around an axis with spaces between
its coils
[SOURCE: ISO 26909:2009, 3.12, modified — limited to wires with circular cross-section]
© ISO 2021 – All rights reserved 1

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ISO 22705-1:2021(E)

3.1.5
cold formed spring
spring formed at ambient temperature
[SOURCE: ISO 26909:2009, 1.12]
3.1.6
active coils
total number of coils less the inactive coils
Note 1 to entry: This is the number of coils used in computing the total deflection of a spring.
[SOURCE: ISO 26909:2009, 5.70, modified — extended to all inactive coils]
3.1.7
test parameter
parameter with a tolerance for which there is an immediate conclusion after the test (within tolerance
or out of tolerance)
Note 1 to entry: Test can be performed without measurement (i.e. with GO/NO-GO gauges).
3.2 Symbols and abbreviated terms
Table 1 includes the symbols and abbreviated terms used throughout this document.
Table 1 — Symbols and abbreviated terms
Symbols Units Designations
D mm outside diameter of spring
e
D mm maximum outside diameter of spring
e,max
D mm minimum outside diameter of spring
e,min
D mm inside diameter of spring
i
D mm maximum inside diameter of spring
i,max
D mm minimum inside diameter of spring
i,min
d mm diameter of wire
d mm maximum diameter of wire
max
d mm actual wire diameter
wire
e mm perpendicularity
1
e mm parallelism
2
F N spring load or force
F N spring load at solid length, L
c c
F N maximum specified spring load
max
F N minimum specified spring load
min
F N spring load for the minimum test length, L
n n
F , F ,… N specified spring loads for the specified spring lengths, L , L ,…
1 2 1 2
L mm solid length
c
L mm maximum specified spring length
max
L mm minimum specified spring length
min
L mm minimum acceptable test length for F
n n
L mm free length
0
L mm maximum free length
0,max
L mm minimum free length
0,min
L , L ,… mm specified spring lengths for the spring loads, F , F ,…
1 2 1 2
2 © ISO 2021 – All rights reserved

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ISO 22705-1:2021(E)

Table 1 (continued)
Symbols Units Designations
n – active coils
n – total number of coils
t
p mm spring pitch
ΔF ΔF
N/mm spring rate (see Annex A)
R= =
ΔL Δs
s mm deflection of spring
s mm deflection of spring for the solid length, L
c c
s mm deflection of the spring (stroke) between two loads, ΔF
h
s mm maximum test spring deflection for the spring load, F
n n
s , s ,… mm specified spring deflections for the specified spring loads, F , F ,…
1 2 1 2
u mm distance between the coils

Figure 1 — Symbols for helical compression springs
4 Environmental conditions
The spatial distribution and equipment of the facility shall permit a reliable implementation of the
measurements and tests. Measurements and tests should be carried out at ambient temperature
in a normal workshop environment. Special tests (e.g. in air-conditioned rooms or other special
environments) shall be agreed upon between the manufacturer and the customer. Measuring and
testing equipment should be subject to regular inspection.
5 Qualifications of the person(s) performing the work
The measurements and tests shall be carried out by a person who has been instructed/trained in the
use of the measuring and testing equipment, as well as regarding methods and test requirements.
The qualifications or additional knowledge and skills should be documented in appropriate qualification
or training documents, depending on the requirements.
© ISO 2021 – All rights reserved 3

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ISO 22705-1:2021(E)

6 Geometries of guiding and supporting devices
If guiding and supporting devices (e.g. test pins, guide sleeves, ring grooves) are used, the properties
(e.g. geometry, material) shall be agreed upon between the manufacturer and the customer to include
special cases such as snapping end coils, buckling or bulging. The alignment of guiding and supporting
devices is aimed to improve the reproducibility of the measurements.
7 Measuring and testing equipment
Suitable measuring equipment shall be selected. Measuring equipment shall conform to ISO standards,
if such are available (e.g. ISO 3611 and ISO 13385-1).
If there is a customer requirement, the methods and measuring equipment shall be agreed on separately.
8 Measurement and test parameter for technical cold formed cylindrical
compression springs
8.1 Free length (L )
0
8.1.1 General
The free length L is a measurement and test parameter.
0
8.1.2 Type of characteristic
L is the length across the entire spring body when no load is applied and only when both ends are
0
ground (see Figure 2); other cases should be agreed upon between the manufacturer and the customer.
Figure 2 — Free length (L) where both ends are closed and ground
0
8.1.3 Measuring and/or testing equipment
The following measuring equipment can be used:
— micrometer gauge;
— calliper;
— dial gauge/indicating calliper;
— electronic measuring sensor;
— manual/automatic force gauge;
— optical measuring instruments/protractor/measurement microscope/camera systems.
The following testing equipment can be used:
— attributive gauges (GO/NO-GO gauges).
4 © ISO 2021 – All rights reserved

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ISO 22705-1:2021(E)

8.1.4 Conditions of measurement and testing
The free length L shall be evaluated at ambient temperature as delivered.
0
8.1.5 Method of measurement and testing
a) Variable measurement
The measurement can be carried out without contact using optical procedures, capacitive or
electrically by contact (with minimal force) or by contact with the measuring surfaces (at a known/
unknown measuring force). Preferably, the measurement should be carried out over the entire face (see
Figure 3). If this is not possible, then a second measurement can be carried out with a 90° offset. In this
case, it shall be clarified whether the maximum value, the minimum value or the average value is to be
specified.
When there is a spring self-weight effect, the measurement of free height should be agreed upon
between the manufacturer and the customer.
Figure 3 — Method of measurement of the free length (L ) with calliper (example)
0
If the customer specifies a setting length for the test spring, the setting conditions for the test spring
shall be agreed upon between the manufacturer and the customer.
Unless otherwise specified, springs that are not pre-set shall only be measured after the spring load
test. If no spring load or force is specified, measurement can be done without any preliminary test.
b) Attributive testing (with GO/NO-GO gauges, see Figure 4)
© ISO 2021 – All rights reserved 5

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ISO 22705-1:2021(E)

a) Tolerance upper limit check with gauge (L ≤ L b) Tolerance upper limit check with gauge (L > L
0 0,- 0 0,-
) (GO/within tolerance) ) (NO GO/out of tolerance)
max max
c) Tolerance lower limit check with gauge d) Tolerance lower limit check with gauge
(L ≥ L ) (NO GO/within tolerance) (L < L ) (GO/out of tolerance)
0 0,min 0 0,min
Figure 4 — Method of testing the free length (L ) with gauges (examples)
0
8.1.6 Test location on the product
The test direction is in the axial direction to the finished spring. When measuring equipment is used
that induces a measuring force, then the applied force should not deflect the spring.
When optical measuring equipment (camera systems) is used, the measurement axis is perpendicular
to the spring axis.
8.2 Outside diameter (D )
e
8.2.1 General
The outside diameter D is a measurement and test parameter.
e
8.2.2 Type of characteristic
D is the value of the outside diameter through the whole spring body (see Figure 5).
e
Figure 5 — Outside diameter (D )
e
6 © ISO 2021 – All rights reserved

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ISO 22705-1:2021(E)

8.2.3 Measurement and/or testing equipment
The following standard measuring equipment can be used:
— micrometer gauge;
— calliper;
— dial gauge.
Alternatively, optical measuring equipment can be used.
In this case, the following testing equipment can be used:
— test sleeve;
— special gauge (part-based);
— snap gauge
...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 22705-1
ISO/TC 227
Springs — Measurement and test
Secretariat: JISC
parameters —
Voting begins on:
2020-12-23
Part 1:
Voting terminates on:
Cold formed cylindrical helical
2021-02-17
compression springs
Ressort - Mesures et paramètres d'essai —
Partie 1: Ressort hélicoïdal de compression cylindrique formé à froid
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 22705-1:2020(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
©
NATIONAL REGULATIONS. ISO 2020

---------------------- Page: 1 ----------------------
ISO/FDIS 22705-1:2020(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/FDIS 22705-1:2020(E)

Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and abbreviated terms . 1
3.1 Terms and definitions . 1
3.2 Symbols and abbreviated terms. 2
4 Environmental conditions . 3
5 Qualifications of the person(s) performing the work . 3
6 Geometries of guiding and supporting devices . 4
7 Measuring and testing equipment . 4
8 Measurement and test parameter for technical cold formed cylindrical
compression springs . 4
8.1 Free length (L ). 4
0
8.1.1 General. 4
8.1.2 Type of characteristic . 4
8.1.3 Measuring and/or testing equipment . 4
8.1.4 Conditions of measurement and testing . 5
8.1.5 Method of measurement and testing . 5
8.1.6 Test location on the product . 6
8.2 Outside diameter (D ) . 6
e
8.2.1 General. 6
8.2.2 Type of characteristic . 6
8.2.3 Measurement and/or testing equipment . 7
8.2.4 Conditions of measurement and testing . 7
8.2.5 Method of measurement and testing . 7
8.2.6 Test location on the product . 9
8.3 Inside diameter (D ) .10
i
8.3.1 General.10
8.3.2 Type of characteristic .10
8.3.3 Measuring and/or testing equipment .10
8.3.4 Conditions of measurement and testing .10
8.3.5 Method of measurement and testing .10
8.3.6 Test location on the product .12
8.4 Total number of coils (n ), number of active coils (n) and coil direction .13
t
8.4.1 General.13
8.4.2 Type of characteristic .13
8.4.3 Measuring and/or testing equipment .15
8.4.4 Conditions of measurement and testing .15
8.4.5 Method of measurement and testing .15
8.4.6 Test location on the product .16
8.5 Applied end coils .16
8.5.1 General.16
8.5.2 Type of characteristic .16
8.5.3 Measuring and/or testing equipment .17
8.5.4 Conditions of measurement and testing .17
8.5.5 Method of measurement and testing .17
8.5.6 Test location on the product .17
8.6 Solid length (L )/solid force (F ) .17
c c
8.6.1 General.17
8.6.2 Type of characteristics .17
8.6.3 Measuring and/or testing equipment .18
8.6.4 Conditions of measurement and testing .18
© ISO 2020 – All rights reserved iii

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ISO/FDIS 22705-1:2020(E)

8.6.5 Method of measurement and testing .18
8.6.6 Test location on the product .19
8.7 Spring load (F) .19
8.7.1 General.19
8.7.2 Type of characteristic .19
8.7.3 Measuring and/or testing equipment .19
8.7.4 Conditions of measurement and testing .19
8.7.5 Method of measurement and testing .20
8.7.6 Test location on the product .20
8.8 Spring pitch (p)/distance between the coils .20
8.8.1 General.20
8.8.2 Type of characteristic .20
8.8.3 Measuring and/or testing equipment .21
8.8.4 Conditions of measurement and testing .21
8.8.5 Method of measurement and testing .21
8.8.6 Test location on the product .21
8.9 Ground surface/angle .21
8.9.1 General.21
8.9.2 Type of characteristic .22
8.9.3 Measuring and/or testing equipment .22
8.9.4 Conditions of measurement and testing .23
8.9.5 Method of measurement and testing .23
8.9.6 Test location on the product .23
8.10 Perpendicularity (e ) .23
1
8.10.1 General.23
8.10.2 Type of characteristic .23
8.10.3 Measuring and/or testing equipment .24
8.10.4 Conditions of measurement and testing .24
8.10.5 Method of measurement and testing .24
8.10.6 Test location on the product .25
8.11 Parallelism (e ) .25
2
8.11.1 General.25
8.11.2 Type of characteristic .25
8.11.3 Measuring and/or testing equipment .25
8.11.4 Conditions of measurement and testing .26
8.11.5 Method of measurement and testing .26
8.11.6 Test location on the product .26
8.12 Shear-off burr .26
8.12.1 General.26
8.12.2 Type of characteristic .27
8.12.3 Measuring and/or testing equipment .27
8.12.4 Conditions of measurement and testing .27
8.12.5 Method of measurement and testing .27
8.12.6 Test location on the product .28
Annex A (informative) Calculation of spring rate (R) .29
Bibliography .30
iv © ISO 2020 – All rights reserved

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ISO/FDIS 22705-1:2020(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 of 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 www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 227, Springs.
A list of all parts in the ISO 22705 series can be found on the ISO website.
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.
© ISO 2020 – All rights reserved v

---------------------- Page: 5 ----------------------
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 22705-1:2020(E)
Springs — Measurement and test parameters —
Part 1:
Cold formed cylindrical helical compression springs
1 Scope
This document specifies the measurement and test methods for the general characteristics of cold
formed helical compression springs made from round wire, excluding dynamic testing.
2 Normative references
There are no normative references in this document.
3 Terms, definitions, symbols and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions 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/
3.1.1
spring
mechanical device designed to store energy when deflected and to return the equivalent amount of
energy when released
[SOURCE: ISO 26909:2009, 1.1]
3.1.2
compression spring
spring that offers resistance to a compressive force applied axially
Note 1 to entry: In the narrow sense, a compression spring indicates a helical compression spring.
[SOURCE: ISO 26909:2009, 1.2]
3.1.3
coil spring
coil-shaped spring
[SOURCE: ISO 26909:2009, 3.11]
3.1.4
helical compression spring
compression spring made of wire of circular cross-section, wound around an axis with spaces between
its coils
[SOURCE: ISO 26909:2009, 3.12, modified — limited to wires with circular cross-section]
© ISO 2020 – All rights reserved 1

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ISO/FDIS 22705-1:2020(E)

3.1.5
cold formed spring
spring formed at ambient temperature
[SOURCE: ISO 26909:2009, 1.12]
3.1.6
active coils
total number of coils less the inactive coils
Note 1 to entry: This is the number of coils used in computing the total deflection of a spring.
[SOURCE: ISO 26909:2009, 5.70, modified — extended to all inactive coils]
3.1.7
test parameter
parameter with a tolerance for which there is an immediate conclusion after the test (within tolerance
or out of tolerance)
Note 1 to entry: Test can be performed without measurement (i.e. with GO/NO-GO gauges).
3.2 Symbols and abbreviated terms
Table 1 includes the symbols and abbreviated terms used throughout this document.
Table 1 — Symbols and abbreviated terms
Symbols Units Designations
D mm outside diameter of spring
e
D mm maximum outside diameter of spring
e,max
D mm minimum outside diameter of spring
e,min
D mm inside diameter of spring
i
D mm maximum inside diameter of spring
i,max
D mm minimum inside diameter of spring
i,min
d mm diameter of wire
d mm maximum diameter of wire
max
d mm actual wire diameter
wire
e mm perpendicularity
1
e mm parallelism
2
F N spring load or force
F N spring load at solid length, L
c c
F N maximum specified spring load
max
F N minimum specified spring load
min
F N spring load for the minimum test length, L
n n
F , F ,… N specified spring loads for the specified spring lengths, L , L ,…
1 2 1 2
L mm solid length
c
L mm maximum specified spring length
max
L mm minimum specified spring length
min
L mm minimum acceptable test length for F
n n
L mm free length
0
L mm maximum free length
0,max
L mm minimum free length
0,min
L , L ,… mm specified spring lengths for the spring loads, F , F ,…
1 2 1 2
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ISO/FDIS 22705-1:2020(E)

Table 1 (continued)
Symbols Units Designations
n – active coils
n – total number of coils
t
p mm spring pitch
ΔF ΔF
N/mm spring rate (see Annex A)
R= =
ΔL Δs
s mm deflection of spring
s mm deflection of spring for the solid length, L
c c
s mm deflection of the spring (stroke) between two loads, ΔF
h
s mm maximum test spring deflection for the spring load, F
n n
s , s ,… mm specified spring deflections for the specified spring loads, F , F ,…
1 2 1 2

Figure 1 — Symbols for helical compression springs
4 Environmental conditions
The spatial distribution and equipment of the facility shall permit a reliable implementation of the
measurements and tests. Measurements and tests should be carried out at ambient temperature
in a normal workshop environment. Special tests (e.g. in air-conditioned rooms or other special
environments) shall be agreed upon between the manufacturer and the customer. Measuring and
testing equipment should be subject to regular inspection.
5 Qualifications of the person(s) performing the work
The measurements and tests shall be carried out by a person who has been instructed/trained in the
use of the measuring and testing equipment, as well as regarding methods and test requirements.
The qualifications or additional knowledge and skills should be documented in appropriate qualification
or training documents, depending on the requirements.
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ISO/FDIS 22705-1:2020(E)

6 Geometries of guiding and supporting devices
If guiding and supporting devices (e.g. test pins, guide sleeves, ring grooves) are used, the properties
(e.g. geometry, material) shall be agreed upon between the manufacturer and the customer to include
special cases such as snapping end coils, buckling or bulging. The alignment of guiding and supporting
devices is aimed to improve the reproducibility of the measurements.
7 Measuring and testing equipment
Suitable measuring equipment shall be selected. Measuring equipment shall conform to ISO standards,
if such are available (e.g. ISO 3611 and ISO 13385-1).
If there is a customer requirement, the methods and measuring equipment shall be agreed on separately.
8 Measurement and test parameter for technical cold formed cylindrical
compression springs
8.1 Free length (L )
0
8.1.1 General
The free length L is a measurement and test parameter.
0
8.1.2 Type of characteristic
L is the length across the entire spring body when no load is applied and only when both ends are
0
ground (see Figure 2); other cases should be agreed upon between the manufacturer and the customer.
Figure 2 — Free length (L) where both ends are closed and ground
0
8.1.3 Measuring and/or testing equipment
The following measuring equipment can be used:
— micrometer gauge;
— calliper;
— dial gauge/indicating calliper;
— electronic measuring sensor;
— manual/automatic force gauge;
— optical measuring instruments/protractor/measurement microscope/camera systems.
The following testing equipment can be used:
— attributive gauges (GO/NO-GO gauges).
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ISO/FDIS 22705-1:2020(E)

8.1.4 Conditions of measurement and testing
The free length L shall be evaluated at ambient temperature as delivered.
0
8.1.5 Method of measurement and testing
a) Variable measurement
The measurement can be carried out without contact using optical procedures, capacitive or
electrically by contact (with minimal force) or by contact with the measuring surfaces (at a known/
unknown measuring force). Preferably, the measurement should be carried out over the entire face (see
Figure 3). If this is not possible, then a second measurement can be carried out with a 90° offset. In this
case, it shall be clarified whether the maximum value, the minimum value or the average value is to be
specified.
When there is a spring self-weight effect, the measurement of free height should be agreed upon
between the manufacturer and the customer.
Figure 3 — Method of measurement of the free length (L ) with calliper (example)
0
If the customer specifies a setting length for the test spring, the setting conditions for the test spring
shall be agreed upon between the manufacturer and the customer.
Unless otherwise specified, springs that are not pre-set shall only be measured after the spring load
test. If no spring load or force is specified, measurement can be done without any preliminary test.
b) Attributive testing (with GO/NO-GO gauges, see Figure 4)
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ISO/FDIS 22705-1:2020(E)

a) Tolerance upper limit check with gauge (L ≤ L b) Tolerance upper limit check with gauge (L > L
0 0,- 0 0,-
) (GO/within tolerance) ) (NO GO/out of tolerance)
max max
c) Tolerance lower limit check with gauge d) Tolerance lower limit check with gauge
(L ≥ L ) (NO GO/within tolerance) (L < L ) (GO/out of tolerance)
0 0,min 0 0,min
Figure 4 — Method of testing the free length (L ) with gauges (examples)
0
8.1.6 Test location on the product
The test direction is in the axial direction to the finished spring. When measuring equipment is used
that induces a measuring force, then the applied force should not deflect the spring.
When optical measuring equipment (camera systems) is used, the measurement axis is perpendicular
to the spring axis.
8.2 Outside diameter (D )
e
8.2.1 General
The outside diameter D is a measurement and
...