ISO/PRF 4027

Fasteners - Hexagon socket set screws with truncated cone point

ISO 4027:2003 specifies the characteristics of hexagon socket set screws with cone point and threads from M1,6 up to and including M24 and of product grade A.

Fixations — Vis sans tête à six pans creux, à bout tronconique

L'ISO 4027:2003 spécifie les caractéristiques des vis sans tête à six pans creux, à bout tronconique, de filetage M1,6 à M24 inclus et de grade A.

General Information

• Status: Not Published
• ICS: 21.060.10 - Bolts, screws, studs
• Technical Committee: ISO/TC 2/SC 11 - Fasteners with metric external thread
• Drafting Committee: ISO/TC 2/SC 11 - Fasteners with metric external thread
• Current Stage: 5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat
• Start Date: 23-Dec-2025
• Completion Date: 27-Dec-2025

Relations

• Revises: ISO 4027:2003 - Hexagon socket set screws with cone point
• Effective Date: 04-Nov-2023

Overview

ISO/PRF 4027 (Fasteners - Hexagon socket set screws with truncated cone point) specifies the characteristics of hexagon socket set screws with a truncated-cone point for product grade A. The document covers metric coarse pitch threads from M1.6 up to M30 for steel and up to M24 for stainless steel. Set screws in this standard are intended to provide secure local fastening and are not intended for use under tensile load.

This edition updates the previous ISO 4027:2003 by clarifying the point geometry, adding M30 for steel, defining diameter determination by formulae, and expanding marking and labelling requirements.

Key Topics

• Scope and applicability: Thread sizes M1.6–M30 (steel) and M1.6–M24 (stainless steel); product grade A.
• Geometry and dimensions: Truncated-cone point form, socket details (including permissible broached form) and dimensional references tied to ISO 225 and ISO 724.
• Tolerances and gauging: Logical tolerance classes and combined gauging for hexagon socket dimensions per ISO 23429; thread tolerance according to ISO 965-1.
• Material and mechanical requirements: Steel and stainless-steel options with hardness and grade selection referenced to ISO 898-5 (steel) and ISO 3506-3 (stainless steel).
• Surface condition and coatings: As-processed (steel) and clean & bright or passivated (stainless); electroplated and zinc-flake coatings referenced by ISO 4042 and ISO 10683.
• Marking and labelling: Product marking is optional unless agreed. Package labelling must include reference to ISO 4027, thread size and nominal length, hardness/grade symbols, surface condition, manufacturer ID, lot number and quantity.

Applications

ISO/PRF 4027 hexagon socket set screws with a truncated-cone point are used where:

• A driven, headless fastener is required to secure components by bearing or friction against a shaft or part surface.
• Localised clamping or positioning is needed without subjecting the fastener to tensile loads.
• Consistent interchangeability, inspection and procurement traceability are required across manufacturing and maintenance operations.

Typical uses include machine assembly, adjustment screws, positioning sets in rotating parts, and applications where a compact headless fastening solution is preferred.

Related Standards

ISO/PRF 4027 references several international standards for dimensions, threads, mechanical properties and inspection. Key related documents include:

• ISO 225, ISO 724 (threads and dimension symbols)
• ISO 965-1 (thread tolerances)
• ISO 898-5 (hardness classes for set screws)
• ISO 3506-3 (stainless steel grades/hardness)
• ISO 23429 (gauging of hexagon sockets)
• ISO 3269, ISO 6157-1 (acceptance and surface discontinuities)

For procurement or implementation, follow ISO 4027 designation rules (examples provided in the standard) and consult the referenced standards for detailed tolerancing, hardness selection and coating specifications.

Keywords: ISO 4027, hexagon socket set screws, truncated cone point, M1.6–M30, product grade A, dimensions, tolerances, hardness, labelling.

Standards Content (Sample)

International
Standard
ISO 4027
Fourth edition
Fasteners — Hexagon socket set
screws with truncated cone point
Fixations — Vis sans tête à six pans creux, à bout tronconique
PROOF/ÉPREUVE
Reference number
ISO 4027:2026(en) © ISO 2026
ISO 4027:2026(en)
© ISO 2026
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
PROOF/ÉPREUVE
ii
ISO 4027:2026(en)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Dimensions . 2
5 Requirements and reference International Standards . 4
6 Marking and labelling . 5
6.1 Marking on product . .5
6.2 Labelling on package .5
7 Designation . 5
Bibliography . 7
PROOF/ÉPREUVE
iii
ISO 4027:2026(en)
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 4027:2003), which has been technically
revised.
The main changes are as follows:
— Title and Scope have been changed from “cone point” to “truncated cone point”;
— M30 has been added for steel hexagon socket set screws;
— the determination of d has been defined by formulae and logical tolerance classes according to the
t,min
ranges of d have been applied;
t,max
— approximate masses have been deleted in Table 2;
— non-ferrous metal screws have been deleted (as a consequence of the withdrawal of ISO 8839);
— for stainless steel fasteners, “Plain” has been changed to “Clean and bright”, and “Passivated” has been
added in Table 3;
— specifications for marking and labelling have been added as Clause 6.
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.
PROOF/ÉPREUVE
iv
International Standard ISO 4027:2026(en)
Fasteners — Hexagon socket set screws with truncated cone
point
1 Scope
This document specifies the characteristics of hexagon socket set screws with truncated cone point, with
metric coarse pitch threads M1,6 to M30 for steel and M1,6 to M24 for stainless steel, and with product
grade A.
Set screws are not intended for use under tensile load.
If in certain cases other specifications are requested, hardness classes and stainless steel grades can be
selected from ISO 898-5 or ISO 3506-3, and dimensional options from ISO 888, ISO 965-1 or ISO 4753.
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 724, ISO general purpose metric screw threads — Basic dimensions
ISO 888, Fasteners — Bolts, screws and studs — Nominal lengths and thread lengths
ISO 898-5, Mechanical properties of fasteners made of carbon steel and alloy steel — Part 5: Set screws and
similar threaded fasteners with specified hardness 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 3506-3, Fasteners — Mechanical properties of corrosion resistant stainless steel fasteners — Part 3: Set
screws (and similar fasteners not under tensile stress) with specified grades and hardness classes
ISO 4042, Fas
...

ISO/TC 2/SC 11
Secretariat: DIN
Date: 2025-12-062026-xx
Fasteners — Hexagon socket set screws with truncated cone point
Fixations — Vis sans tête à six pans creux, à bout tronconique
PROOF
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VotVoting beging beginins s oon:n: 20202626--0101--0101
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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
EmailE-mail: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword . iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Dimensions. 2
5 Requirements and reference International Standards . 4
6 Marking and labelling . 5
6.1 Marking on product . 5
6.2 Labelling on package . 5
7 Designation . 6
Bibliography . 7

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 4027:2003), which has been technically revised.
The main changes are as follows:
— — Title and Scope have been changed from “cone point” to “truncated cone point”;
— — M30 has been added for steel hexagon socket set screws;
— — the determination of d has been defined by formulae and logical tolerance classes according to the
t,min
ranges of dt,max have been applied;
— — approximate masses have been deleted in Table 2;
— — non-ferrous metal screws have been deleted (as a consequence of the withdrawal of ISO 8839);
— — for stainless steel fasteners, “Plain” has been changed to “Clean and bright”, and “Passivated” has been
added in Table 3;
— — specifications for marking and labelling have been added as Clause 6.
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
Fasteners — Hexagon socket set screws with truncated cone point
1 Scope
This document specifies the characteristics of hexagon socket set screws with truncated cone point, with
metric coarse pitch threads M1,6 to M30 for steel and M1,6 to M24 for stainless steel, and with product
grade A.
Set screws are not intended for use under tensile load.
If in certain cases other specifications are requested, hardness classes and stainless steel grades can be
selected from ISO 898--5 or ISO 3506--3, and dimensional options from ISO 888, ISO 965-1 or ISO 4753.
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 724, ISO general purpose metric screw threads — Basic dimensions
ISO 888, Fasteners — Bolts, screws and studs — Nominal lengths and thread lengths
ISO 898--5, Mechanical properties of fasteners made of carbon steel and alloy steel — Part 5: Set screws and
similar threaded fasteners with specified hardness 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--3, Fasteners — Mechanical properties of corrosion resistant stainless steel fasteners — Part 3: Set
screws (and similar fasteners not under tensile stress) with specified grades and hardness 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 ge
...