SIST EN ISO 22705-2:2025

SLOVENSKI STANDARD
01-december-2025
Vzmeti - Merilni in preskusni parametri - 2. del: Hladno oblikovane cilindrične
vijačne vzmeti (ISO 22705-2:2023)
Springs - Measurement and test parameters - Part 2: Cold formed cylindrical helical
extension springs (ISO 22705-2:2023)
Federn - Mess- und Prüfparameter - Teil 2: Kaltgeformte zylindrische
Schraubenzugfedern (ISO 22705-2:2023)
Ressort - Mesures et paramètres d'essai - Partie 2: Ressort hélicoïdal de traction
cylindrique formé à froid (ISO 22705-2:2023)
Ta slovenski standard je istoveten z: EN ISO 22705-2:2025
ICS:
21.160 Vzmeti Springs
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 22705-2
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2025
EUROPÄISCHE NORM
ICS 21.160
English Version
Springs - Measurement and test parameters - Part 2: Cold
formed cylindrical helical extension springs (ISO 22705-
2:2023)
Ressorts - Mesures et paramètres d'essai - Partie 2: Federn - Mess- und Prüfgrößen - Teil 2: Kaltgeformte
Ressorts hélicoïdaux de traction cylindriques formés à zylindrische Schraubenzugfedern (ISO 22705-2:2023)
froid (ISO 22705-2:2023)
This European Standard was approved by CEN on 29 September 2025.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 22705-2:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
The text of ISO 22705-2:2023 has been prepared by Technical Committee ISO/TC 227 "Springs” of the
International Organization for Standardization (ISO) and has been taken over as EN ISO 22705-2:2025
by Technical Committee CEN/TC 407 “Technical springs” the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by April 2026, and conflicting national standards shall be
withdrawn at the latest by April 2026.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 22705-2:2023 has been approved by CEN as EN ISO 22705-2:2025 without any
modification.
INTERNATIONAL ISO
STANDARD 22705-2
First edition
2023-02
Springs — Measurement and test
parameters —
Part 2:
Cold formed cylindrical helical
extension springs
Ressort - Mesures et paramètres d'essai —
Partie 2: Ressort hélicoïdal de traction cylindrique formé à froid
Reference number
ISO 22705-2:2023(E)
ISO 22705-2:2023(E)
© ISO 2023
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: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 22705-2:2023(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 . 3
7 Measuring and testing equipment . 3
8 Measurement and test parameter for technical cold formed cylindrical extension
springs . 4
8.1 Free length (L ) . 4
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 . 4
8.1.5 Method of measurement and testing . 4
8.1.6 Test location on the product. 7
8.2 Body length (L ) . 7
B
8.2.1 General . 7
8.2.2 Type of characteristic . 7
8.2.3 Measuring and/or testing equipment . 8
8.2.4 Conditions of measurement and testing . 8
8.2.5 Method of measurement and testing . 8
8.2.6 Test location on the product. 10
8.3 Spring hook length (L ) . 10
H
8.3.1 General . 10
8.3.2 Type of characteristic . 10
8.3.3 Measuring and/or testing equipment . 11
8.3.4 Conditions of measurement and testing . 11
8.3.5 Method of measurement and testing . 11
8.3.6 Test location on the product. 13
8.4 Hook opening (m) . 13
8.4.1 General .13
8.4.2 Type of characteristic . 13
8.4.3 Measuring and/or testing equipment . 14
8.4.4 Conditions of measurement and testing . 14
8.4.5 Method of measurement and testing . 14
8.4.6 Test location on the product. 15
8.5 Outside diameter (D ). 15
e
8.5.1 General .15
8.5.2 Type of characteristic . 15
8.5.3 Measurement and/or testing equipment . 16
8.5.4 Conditions of measurement and testing . 16
8.5.5 Method of measurement and testing . 16
8.5.6 Test location on the product. 20
8.6 Inside diameter (D ) .20
i
8.6.1 General .20
8.6.2 Type of characteristic . 20
8.6.3 Measuring and/or testing equipment . 20
8.6.4 Conditions of measurement and testing . 20
iii
ISO 22705-2:2023(E)
8.6.5 Method of measurement and testing . 21
8.6.6 Test location on the product. 23
8.7 Total number of coils (n ), number of active coils (n) and coil direction .23
t
8.7.1 General .23
8.7.2 Type of characteristic . 23
8.7.3 Measuring and/or testing equipment . 25
8.7.4 Conditions of measurement and testing . 25
8.7.5 Method of measurement and testing . 25
8.7.6 Test location on the product. 26
8.8 Bending radius (r) .26
8.8.1 General . 26
8.8.2 Type of characteristic . 26
8.8.3 Measuring and/or testing equipment . 27
8.8.4 Conditions of measurement and testing . 27
8.8.5 Method of measurement and testing . 27
8.8.6 Test location on the product. 27
8.9 Spring load (F) .28
8.9.1 General .28
8.9.2 Type of characteristic .28
8.9.3 Measuring and/or testing equipment .28
8.9.4 Conditions of measurement and testing .28
8.9.5 Method of measurement and testing .28
8.9.6 Test location on the product.29
8.10 Spring pitch (p) / distance between the coils (u) .29
8.10.1 General .29
8.10.2 Type of characteristic .29
8.10.3 Measuring and/or testing equipment .30
8.10.4 Conditions of measurement and testing .30
8.10.5 Method of measurement and testing .30
8.10.6 Test location on the product.30
8.11 Loop/ Hook position . 31
8.11.1 General . 31
8.11.2 Type of characteristic . 31
8.11.3 Measuring and/or testing equipment . 31
8.11.4 Conditions of measurement and testing . 32
8.11.5 Method of measurement and testing . 32
8.11.6 Test location on the product. 32
8.12 Shear-off burr . 32
8.12.1 General . 32
8.12.2 Type of characteristic . 32
8.12.3 Measuring and/or testing equipment . 33
8.12.4 Conditions of measurement and testing . 33
8.12.5 Method of measurement and testing . 33
8.12.6 Test location on the product.34
Annex A (Informative) Calculation of spring rate R .35
Annex B (Informative) Calculation of initial tension force (F ) .36
i
Annex C (Informative) Types of hooks .38
iv
ISO 22705-2:2023(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.
v
INTERNATIONAL STANDARD ISO 22705-2:2023(E)
Springs — Measurement and test parameters —
Part 2:
Cold formed cylindrical helical extension springs
1 Scope
This document specifies the measurement and test methods for general characteristics of cold formed
helical extension springs made from round wire, excluding dynamic testing.
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 3611, Geometrical product specifications (GPS) — Dimensional measuring equipment: Micrometers for
external measurements — Design and metrological characteristics
ISO 13385-1, Geometrical product specifications (GPS) — Dimensional measuring equipment — Part 1:
Design and metrological characteristics of callipers
ISO 16249, Springs — Symbols
ISO 26909, Springs — Vocabulary
3 Terms, definitions, symbols and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 26909 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1.1
helical extension spring
extension spring normally made of wire of circular cross-section, wound around an axis, with or
without spaces between its coils (open or closed wound)
[SOURCE: ISO 26909:2009, 3.13, modified — limited to wires with circular cross-section]
3.1.2
test parameter
parameter with a tolerance for which there is an immediate conclusion after test (within tolerance or
out of tolerance)
Note 1 to entry: Test can be done without measurement (i.e. with GO/NO GO gauges).
ISO 22705-2:2023(E)
3.2 Symbols and abbreviated terms
For the purposes of this document, the symbols given in ISO 16249, Figure 1 and Table 1 apply.
Table 1 — Symbols and abbreviated terms
Symbols Units Designations
D mm outside diameter of spring
e
D mm inside diameter of spring
i
d mm diameter of wire
d mm maximum diameter of wire
max
d mm actual wire diameter
wire
F N spring load or force
F = F – s R N initial tension force (preload) (see Annex B)
i 1 1
F , F ,… N specified spring loads for the specified spring lengths, L , L ,…
1 2 1 2
F N maximum permissible spring force for the maximum permissible spring length L
n n
F N maximum specified spring load
max
F N minimum specified spring load
min
L mm free length
L mm maximum acceptable spring length measured spring hooks inner radii for F
n n
L , L ,… mm specified spring lengths for the spring loads, F , F ,…
1 2 1 2
L mm distance from inner radius of loop to spring body
H
L mm body length when unloaded but subject to initial tension force
B
L mm maximum specified spring length
max
L mm minimum specified spring length
min
m mm hook opening
n – number of active coils
n – total number of coils
t
p mm spring pitch
ΔF ΔF
N/mm spring rate (see Annex A)
R==
ΔL Δs
r mm bending radius
s mm deflection of spring
s mm maximum test spring deflection for the spring loads, F
n n
s , s ,… mm specified spring deflections for the specified spring loads, F , F ,…
1 2 1 2
s mm deflection of spring (stroke) between two loads
h
u mm distance between the coils

ISO 22705-2:2023(E)
Figure 1 — Symbols for helical extension spring
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.
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. The alignment of guiding and supporting devices is aimed to improve the reproducibility
of the measures (e.g. diameter of pins inserted inside the hooks to measure the loads).
7 Measuring and testing equipment
Suitable measuring equipment shall be selected. Measuring equipment shall conform to ISO 3611 and
ISO 13385-1.
If there is a customer requirement, the methods and measuring equipment shall be agreed on separately.
ISO 22705-2:2023(E)
8 Measurement and test parameter for technical cold formed cylindrical
extension springs
8.1 Free length (L )
8.1.1 General
The free length L is a measurement and test parameter.
8.1.2 Type of characteristic
The free length L is the length between the two internal hooks when no load is applied (see Figure 2);
other cases should be agreed upon between the manufacturer and the customer. If it’s not possible to
measure L inside the hooks, it shall be measured outside the hooks minus two times wire diameter
(2d).
a) Full loop b) Raised hook
Figure 2 — Free length (L )
8.1.3 Measuring and/or testing equipment
The following measuring equipment can be used:
— micrometer gauge;
— calliper;
— electronic measuring sensor;
— manual/automatic force gauge;
— optical measuring instruments/ measurement microscope/camera systems;
The following testing equ
...