EN ISO 14581:2023

Fasteners - Hexalobular socket countersunk flat head screws (common head style) with reduced loadability (ISO 14581:2022)

This document specifies the characteristics of hexalobular socket countersunk flat head screws with reduced loadability due to head design, in steel and stainless steel, with metric coarse pitch threads M2 to M10, and with product grade A.
If in certain cases other specifications are requested, stainless steel grades can be selected from ISO 3506‑1, and dimensional options from ISO 888 or ISO 4753.
NOTE 1   The reduced loadability (related to the countersunk head dimensions in combination with penetration of the hexalobular socket specified in this document) implies a limitation of ultimate tensile load shown by a specific marking (property class preceded by a zero). The loadability in the head is assumed to be 80 % of that in the thread for all sizes and all property classes; see Table 3.
NOTE 2   Hexalobular socket countersunk head screws (high head), with full loadability are specified in ISO 14582, but these products are not interchangeable, because of different head heights.
NOTE 3   Particular attention is needed to ensure alignment of the countersunk head with the bearing surface of the countersink in the assembly.

Verbindungselemente - Senkschrauben mit Innensechsrund (Einheitskopf) mit reduzierter Belastbarkeit (ISO 14581:2022)

Dieses Dokument legt die Eigenschaften von Senkschrauben mit Innensechsrund mit reduzierter Belastbarkeit aufgrund ihrer Kopfgeometrie in Stahl und nichtrostendem Stahl mit metrischen Regelgewinden von M2 bis M10 in Produktklasse A fest.
Falls in bestimmten Fällen andere Festlegungen gefordert werden, können die nichtrostenden Stahlsorten nach ISO 3506 1 und maßliche Alternativen nach ISO 888 oder ISO 4753 ausgewählt werden.
ANMERKUNG 1   Die reduzierte Belastbarkeit (bezogen auf die Kopfgeometrie in Kombination mit der in diesem Dokument festgelegten Eindringtiefe des Innensechsrunds) bringt eine Begrenzung der Mindestbruchkraft mit sich, die durch eine spezifische Kennzeichnung (Festigkeitsklasse mit vorangestellter Null) angezeigt wird. Es wird angenommen, dass die Belastbarkeit im Kopf 80 % der Belastbarkeit im Gewinde für alle Größen und alle Festigkeitsklassen beträgt; siehe Tabelle 3.
ANMERKUNG 2   Senkkopfschrauben mit Innensechsrund (mit hohem Kopf) mit voller Belastbarkeit sind in ISO 14582 festgelegt, jedoch sind diese Produkte aufgrund unterschiedlicher Kopfhöhen nicht austauschbar.
ANMERKUNG 3   Besondere Aufmerksamkeit ist notwendig, um ein Fluchten des Senkkopfes mit der Auflagefläche der Ansenkung in der Baugruppe sicherzustellen.

Fixations - Vis à tête fraisée (tête commune) à six lobes internes à capacité de charge réduite (ISO 14581:2022)

Le présent document spécifie les caractéristiques des vis à tête fraisée à six lobes internes à capacité de charge réduite du fait de la conception de la tête, en acier et en acier inoxydable, à filetage métrique à pas gros M2 à M10, et de grade A.
Si dans certains cas d’autres spécifications sont requises, les grades d’acier inoxydable peuvent être choisis dans l'ISO 3506‑1, et les options dimensionnelles dans l'ISO 888 ou l'ISO 4753.
NOTE 1      La capacité de charge réduite (du fait des dimensions de la tête fraisée et de la profondeur de pénétration du six pans creux spécifiées dans le présent document) implique une limitation de la charge minimale de rupture à la traction, indiquée par un marquage spécifique (classe de qualité prédédée d’un zéro). La capacité de charge dans la tête est considérée comme égale à 80 % de la résistance du filetage pour toutes les dimensions et pour toutes les classes de qualité; voir Tableau 3.
NOTE 2      Les vis à tête fraisée à six lobes internes (tête haute), à capacité de charge intégrale, sont spécifiées dans l’ISO 14582, mais ces produits ne sont pas interchangeables en raison de hauteurs de tête différentes.
NOTE 3      Une attention toute particulière est nécessaire pour assurer l’alignement de la tête fraisée avec la fraisure de la surface d’appui lors de l’assemblage.

Vezni elementi - Notranji šestrogeljnik v ugrezni ploski glavi vijaka (običajna oblika glave) z manjšo obremenljivostjo (ISO 14581:2022)

Ta dokument določa lastnosti vijakov z notranjim šestrogeljnikom v ugrezni ploski glavi z manjšo obremenljivostjo zaradi zasnove glave, v jeklu in nerjavnem jeklu, z grobim metričnim navojem velikosti od M2 do M10, in razredom izdelave A.
Če se v določenih primerih zahtevajo druge specifikacije, je razrede lastnosti nerjavnega jekla mogoče izbrati po standardu ISO 3506-1, dimenzijske možnosti pa po ISO 888 ali ISO 4753.
OPOMBA 1: Zmanjšana obremenljivost (povezana z dimenzijami ugreznjene glave v kombinaciji s prebojem šestrogeljnika, navedenega v tem dokumentu) pomeni omejitev končne natezne sile, ki ima posebno oznako (razred lastnosti z ničlo na začetku). Predpostavlja se, da je obremenljivost v glavi 80 % tiste v navoju za vse velikosti in vse razrede lastnosti; glej preglednico 3.
OPOMBA 2: V standardu ISO 14582 so določeni vijaki s šestrogeljnikom v ugreznjeni glavi (visoka glava) s polno obremenljivostjo, vendar ti izdelki zaradi različnih višin glave niso zamenljivi.
OPOMBA 3: Posebej je treba paziti na poravnavo ugreznjene glave z naležno površino ugreza v sklopu.

General Information

• Status: Published
• Publication Date: 10-Jan-2023
• ICS: 21.060.10 - Bolts, screws, studs
• Technical Committee: CEN/TC 185 - Threaded and nonthreaded mechanical fasteners and accessories
• Drafting Committee: CEN/TC 185 - Threaded and nonthreaded mechanical fasteners and accessories
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 11-Jan-2023
• Completion Date: 11-Jan-2023
• Ref Project: SIST EN ISO 14581:2023 - Fasteners - Hexalobular socket countersunk flat head screws (common head style) with reduced loadability (ISO 14581:2022)

Relations

• Replaces: EN ISO 14581:2013 - Fasteners - Hexalobular socket countersunk flat head screws (ISO 14581:2013)
• Effective Date: 16-Jan-2023

Overview

EN ISO 14581:2023 (ISO 14581:2022) defines requirements for hexalobular socket countersunk flat head screws (common head style) with reduced loadability. It covers steel and stainless‑steel fasteners with metric coarse pitch threads M2 to M10, product grade A. The standard specifies head dimensions, gauging, marking, labelling and performance limits that arise from the reduced head geometry and hexalobular socket penetration.

Key topics and requirements

• Scope and materials: Applies to steel and stainless‑steel screws, M2–M10, product grade A. Stainless‑steel grades can be selected per ISO 3506‑1 when other specifications are requested.
• Reduced loadability: The head design (countersunk head dimensions combined with socket penetration) reduces ultimate tensile load in the head. Loadability in the head is assumed to be 80% of that in the thread for all sizes/property classes. Reduced loadability is indicated by a property class preceded by a zero on the marking.
• Dimensions & gauging: Detailed head dimensions, minimum head height, radius and underhead reinforcement (where applicable) are specified. Dimensional options may reference ISO 888 or ISO 4753.
• Marking and labelling: Requirements for product marking (including property class notation for reduced loadability) and package labelling are included.
• Design and inspection: Figures and tables define head configuration, gauging criteria and minimum tensile loads (with calculations for small sizes M2 and M2.5 where needed).
• Interchangeability: These reduced‑load countersunk flat head screws are not interchangeable with the high‑head full‑load hexalobular countersunk screws specified in ISO 14582 due to different head heights.
• Assembly guidance: Emphasises correct alignment of the countersunk head with the countersink bearing surface to ensure performance.

Applications and users

• Typical applications: flush, countersunk fastenings in electronics, enclosures, automotive trim, precision assemblies and any design requiring a flush head where reduced head material is acceptable.
• Who uses it: mechanical designers, fastener manufacturers, procurement teams, quality/inspection engineers and assembly technicians specifying or verifying hexalobular socket countersunk flat head screws with reduced loadability.
• Practical value: ensures consistent dimensions, predictable reduced tensile performance, and clear marking so designers and assemblers can select appropriate screws and avoid mismating with full‑load variants.

Related standards

• ISO 14582 - hexalobular countersunk head screws (high head, full loadability)
• ISO 3506‑1 - stainless‑steel fastener grades
• ISO 7721 - countersunk head configuration and gauging
• ISO 888 / ISO 4753 - length and end‑of‑part dimensional options
• ISO 898‑1, ISO 10664, ISO 8991 - fastener mechanical/design referencing

Keywords: EN ISO 14581:2023, ISO 14581:2022, hexalobular socket countersunk flat head screws, reduced loadability, fasteners, M2–M10, product grade A.

Standards Content (Sample)

SLOVENSKI STANDARD
01-marec-2023
Nadomešča:
SIST EN ISO 14581:2014
Vezni elementi - Notranji šestrogeljnik v ugrezni ploski glavi vijaka (običajna oblika
glave) z manjšo obremenljivostjo (ISO 14581:2022)
Fasteners - Hexalobular socket countersunk flat head screws (common head style) with
reduced loadability (ISO 14581:2022)
Verbindungselemente - Senkschrauben mit Innensechsrund (Einheitskopf) mit
reduzierter Belastbarkeit (ISO 14581:2022)
Fixations - Vis à tête fraisée (tête commune) à six lobes internes à capacité de charge
réduite (ISO 14581:2022)
Ta slovenski standard je istoveten z: EN ISO 14581:2023
ICS:
21.060.10 Sorniki, vijaki, stebelni vijaki Bolts, screws, studs
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 14581
EUROPEAN STANDARD
NORME EUROPÉENNE
January 2023
EUROPÄISCHE NORM
ICS 21.060.10 Supersedes EN ISO 14581:2013
English Version
Fasteners - Hexalobular socket countersunk flat head
screws (common head style) with reduced loadability (ISO
14581:2022)
Fixations - Vis à tête fraisée (tête commune) à six lobes Verbindungselemente - Senkschrauben mit
internes à capacité de charge réduite (ISO 14581:2022) Innensechsrund (Einheitskopf) mit reduzierter
Belastbarkeit (ISO 14581:2022)
This European Standard was approved by CEN on 26 November 2022.

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
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 14581:2023 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 14581:2023) has been prepared by Technical Committee ISO/TC 2 "Fasteners"
in collaboration with Technical Committee CEN/TC 185 “Fasteners” the secretariat of which is held by
BSI.
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 July 2023, and conflicting national standards shall be
withdrawn at the latest by July 2023.
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.
This document supersedes EN ISO 14581:2013.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. 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 14581:2022 has been approved by CEN as EN ISO 14581:2023 without any modification.

INTERNATIONAL ISO
STANDARD 14581
Second edition
2022-12
Fasteners — Hexalobular socket
countersunk flat head screws
(common head style) with reduced
loadability
Fixations — Vis à tête fraisée (tête commune) à six lobes internes à
capacité de charge réduite
Reference number
ISO 14581:2022(E)
ISO 14581:2022(E)
© ISO 2022
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 14581:2022(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Dimensions and gauging of the head .2
4.1 Dimensions . 2
4.2 Gauging of head . 7
5 Requirements and reference International Standards . 7
6 Marking and labelling . 8
6.1 Marking on product . . 8
6.2 Labelling on package . 8
7 Designation . 9
Annex A (informative) Minimum ultimate tensile loads for screws M2 and M2,5 with full
loadability .10
Bibliography .11
iii
ISO 14581:2022(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 2, Fasteners, Subcommittee SC 11,
Fasteners with metric external thread, in collaboration with the European Committee for Standardization
(CEN) Technical Committee CEN/TC 185, Fasteners, in accordance with the Agreement on technical
cooperation between ISO and CEN (Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 14581:2013), which has been technically
revised.
The main changes are as follows:
— the whole standard (including title) has been improved to clearly point out that these hexalobular
socket countersunk flat head screws with common head style have reduced loadability because of
their head design (head dimensions and penetration of the hexalobular socket);
— for M2 to M4, partially threaded screws without underhead reinforcement (formerly designated as
“shoulder”) and normative reference to ISO 3508 for x (see figure footnote e) have been added
max
(see Figure 1 b);
— for M5 to M10, underhead reinforcement has been modified from a radius to a conical shape as
adjustment to manufacturing conditions and normative reference to ISO 3508 for x (see figure
max
footnote e) has been added (see Figure 2 b);
— detailed head configuration has been added (see Figure 3);
— shank diameter d has been added in Table 1;
s
— minimum head height k has been added as reference dimension in Table 1;
min
— radius r has been specified for all head configurations (see Figures 1 and 2), and r has been added
min
in Table 1;
— shortest standard lengths l have been increased in Table 1;
nom
iv
ISO 14581:2022(E)
— calculations for M2 and M2,5 have been added in Table 3 for steel screws; as their minimum
ultimate tensile loads for full loadability are not specified in ISO 898-1 and ISO 3506-1, they have
been calculated with the same formulae accordingly (see Table A.1, Annex A);
— the minimum ultimate tensile loads were recalculated and have been changed to more precise
values for steel screws with property classes 4.8 (M3 and M6), 8.8 (M5), and for stainless steel
screws with property classes 50 (M3, M6 and M8) and 70 (M3, M6, M8 and M10); see Table 3;
— property class 10.9 has been added (see Table 2);
— specifications for labelling have been added as new subclause 6.2;
— reference to ISO 15065 for countersinks has been added.
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 14581:2022(E)
Fasteners — Hexalobular socket countersunk flat head
screws (common head style) with reduced loadability
1 Scope
This document specifies the characteristics of hexalobular socket countersunk flat head screws with
reduced loadability due to head design, in steel and stainless steel, with metric coarse pitch threads M2
to M10, and with product grade A.
If in certain cases other specifications are requested, stainless steel grades can be selected from
ISO 3506-1, and dimensional options from ISO 888 or ISO 4753.
NOTE 1 The reduced loadability (related to the countersunk head dimensions in combination with penetration
of the hexal
...