ISO/FDIS 10642

FINAL DRAFT
International
Standard
ISO/TC 2/SC 11
Fasteners — Hexagon socket
Secretariat: DIN
countersunk head screws with
Voting begins on:
reduced loadability
2025-12-12
Fixations — Vis à tête fraisée à six pans creux à capacité de
Voting terminates on:
charge réduite
2026-02-06
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BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
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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.
Reference number
FINAL DRAFT
International
Standard
ISO/TC 2/SC 11
Fasteners — Hexagon socket
Secretariat: DIN
countersunk head screws with
Voting begins on:
reduced loadability
Fixations — Vis à tête fraisée à six pans creux à capacité de
Voting terminates on:
charge réduite
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.
© ISO 2025
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/CEN PARALLEL PROCESSING
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
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Published in Switzerland Reference number
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Dimensions and gauging of head . 2
4.1 Dimensions .2
4.1.1 Gauging of head .6
5 Requirements and reference International Standards . 6
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 bolts and screws with full loadability,
coarse pitch threads M2 and M2,5 . 10
Bibliography .11

iii
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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 fourth edition cancels and replaces the third edition (ISO 10642:2019), which has been technically
revised.
The main changes are as follows:
— Note 2 in Clause 1, Scope, editorially improved;
— Figure 4 corrected with d substituted by D ;
a
— Footnote e in Tables 1 and 2 corrected in the second sentence: Values for k are in relation to D .;
min a
— Footnote f in Figure 1 corrected to a ≤ 3P;
— Footnote h in Table 1 and Table 2 corrected to 3P;
— Table 4 editorially revised according to the latest template for product standards;
— Table 5 revised according to the latest agreed rounding rules for fasteners with reduced loadability and
wrong value for M3 with property class 12,9 corrected;
— Labelling on package (6.2) editorially improved;
— Clause 7, Designation, editorially revised according to the latest template for product standards;
— value for M2, property class 70 in Table A.1 in Annex A corrected to the new rounding rules and Footnote
a adjusted accordingly.
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.

iv
FINAL DRAFT International Standard ISO/FDIS 10642:2025(en)
Fasteners — Hexagon socket countersunk head screws with
reduced loadability
1 Scope
This document specifies the characteristics of hexagon socket countersunk head screws with reduced
loadability due to head design, in steel and stainless steel, with metric coarse pitch threads M2 to M20, and
with product grade A.
NOTE 1 Other dimensional options are given in ISO 888, ISO 965-1 and ISO 4753.
NOTE 2 The reduced loadability (related to the countersunk head dimensions in combination with penetration
of the hexagon 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 5.
NOTE 3 Particular attention is needed to ensure alignment of the countersunk head with the bearing surface of the
countersink in the assembly.
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 225, Fasteners — Bolts, screws, studs and nuts — Symbols and descriptions of dimensions
ISO 898-1, Mechanical properties of fasteners made of carbon steel and alloy steel — Part 1: Bolts, screws and
studs with specified property classes — Coarse thread and fine pitch thread
ISO 965-1, ISO general purpose metric screw threads — Tolerances — Part 1: Principles and basic data
ISO 1891-4, Fasteners — Vocabulary — Part 4: Control, inspection, delivery, acceptance and quality
ISO 3269, Fasteners — Acceptance inspection
ISO 3506-1, Fasteners — Mechanical properties of corrosion-resistant stainless steel fasteners — Part 1: Bolts,
screws and studs with specified grades and property classes
ISO 4042, Fasteners — Electroplated coating systems
ISO 4753, Fasteners — Ends of parts with external ISO metric thread
ISO 4759-1, Tolerances for fasteners — Part 1: Bolts, screws, studs and nuts — Product grades A, B and C
ISO 6157-1, Fasteners — Surface discontinuities — Part 1: Bolts, screws and studs for general requirements
ISO 6157-3, Fasteners — Surface discontinuities — Part 3: Bolts, screws and studs for special requirements
ISO 8991, Designation system for fasteners
ISO 8992, Fasteners — General requirements for bolts, screws, studs and nuts
ISO 10683, Fasteners — Non-electrolytically applied zinc flake coating systems

3 Terms and definitions
No terms and definitions are listed in this document.
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/
4 Dimensions and gauging of head
4.1 Dimensions
Dimensions shall be in accordance with Figures 1 to 4 and Tables 1 and 2.
Symbols and descriptions of dimensions shall be as specified in ISO 225.
a) Partially threaded screw
b) Screw threaded to the head
a
A slight rounding or countersink at the mouth of the socket is permissible.
b
In accordance with ISO 4753: chamfered end (CH), but for sizes ≤ M4 as rolled end (RL) is also allowed.
c
Edge of the head flat or rounded.
d
Incomplete thread u ≤ 2P.
e
d applies when values for l are specified in Tables 1 and 2.
s s,min
f
In accordance with ISO 3508: a ≤ 3P.
Figure 1 — Hexagon socket countersunk head screws

ISO/FD
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