SIST EN ISO 21368:2023

Adhesives - Guidelines for the fabrication of adhesively bonded structures and reporting procedures suitable for the risk evaluation of such structures (ISO 21368:2022)

This document provides guidelines describing the adhesive bonding quality requirements suitable for use by adhesive user-companies utilizing adhesive bonding as a means of fabrication. In particular, the guidelines define various approaches to meeting quality requirements for fabrication and reporting procedures, both in workshops and on site. These guidelines aim to convey the importance of maintaining quality standards in fabrication and reporting procedures, keeping records and thus enabling documentation to provide the basis for risk evaluation of adhesively bonded structures in service and in use.
These guidelines have been prepared such that:
a) they are independent of the type of adhesively bonded structure;
b) they are independent of adhesive user-companies’ and suppliers’ product recommendations;
c) they define the quality requirements for adhesive bonding in terms of fabrication and reporting procedures, both in workshops and on site;
d) they can be used as the basis for risk evaluation of adhesively bonded structures in service and in use;
e) they can be used as a basis for assessing a fabricator's capability to produce adhesively bonded structures fulfilling specified quality requirements when they are detailed in one or more of the following:
—    a contract between the parties involved;
—    an application standard;
—    a regulatory statement.
The guidelines contained within this document can be adopted in full or selectively chosen by the adhesive user to suit the structure concerned. The guidelines provide a flexible framework for the control of adhesive bonding activities in the following cases.
Case 1
The provision of specific requirements for adhesive bonding in contracts that require the adhesive user to have a quality system other than ISO 9001.
Case 2
The provision of specific requirements for adhesive bonding as guidance to an adhesive user developing a quality system.
Case 3
The provision of specific requirements for references in application standards that uses adhesive bonding as part of its requirements or in a contract between relevant parties.
Case 4
The provision of a framework for fabrication and reporting procedures to a quality standard, suitable in particular as a basis for the risk evaluation of adhesively bonded structures.

Klebstoffe - Richtlinien für die Herstellung geklebter Strukturen und Berichtsverfahren, die für die Risikobewertung solcher Strukturen geeignet sind (ISO 21368:2022)

Dieses Dokument enthält Leitlinien zur Beschreibung der Qualitätsanforderungen an das Kleben, die für Anwenderunternehmen geeignet sind, die Kleben als Fertigungsverfahren einsetzen. Insbesondere werden in den Leitlinien verschiedene Ansätze zur Erfüllung der Qualitätsanforderungen an die Herstellungs- und Berichtsverfahren sowohl in den Betrieben als auch auf der Baustelle definiert. Diese Leitlinien sollen vermitteln, wie wichtig es ist, Qualitätsstandards bei der Herstellung und bei der Berichterstattung einzuhalten, Aufzeichnungen zu führen und so eine Dokumentation zu ermöglichen, die die Grundlage für die Risikobewertung geklebter Strukturen im Betrieb und in der Anwendung bildet.
Diese Leitlinien wurden so erstellt, dass:
a)   sie unabhängig von der Art der geklebten Struktur sind;
b)   sie unabhängig von den Produktempfehlungen der Klebstoffanwender und  lieferanten sind;
c)   sie die Qualitätsanforderungen für Klebverbindungen in Bezug auf die Herstellungs- und Berichtsverfahren, sowohl in Betrieben als auch auf der Baustelle definieren;
d)   sie als Grundlage für die Risikobewertung geklebter Strukturen im Betrieb und in der Anwendung verwendet werden können;
e)   sie als Grundlage für die Beurteilung der Fähigkeit eines Anwenders dienen können, geklebte Strukturen herzustellen, die die festgelegten Qualitätsanforderungen erfüllen, wenn sie in einem oder mehreren der folgenden Punkte aufgeführt sind:
   ein Vertrag zwischen den beteiligten Parteien;
   ein Anwendungsstandard;
   eine Erklärung zur Regulierung.
Die in diesem Dokument enthaltenen Leitlinien können vollständig übernommen oder vom Klebstoffanwender je nach Struktur selektiv ausgewählt werden. Die Leitlinien bieten einen flexiblen Rahmen für die Kontrolle von Klebarbeiten in den folgenden Fällen.
Fall 1
Die Festlegung spezifischer Anforderungen für Klebverbindungen in Verträgen, die vom Klebstoffanwender ein anderes Qualitätssystem als ISO 9001 verlangen.
Fall 2
Die Festlegung spezifischer Anforderungen für das Kleben als Anleitung für einen Klebstoffanwender, der ein Qualitätssystem entwickelt.
Fall 3
Die Festlegung spezifischer Anforderungen für Verweise in Anwendungsnormen, die Kleben als Teil ihrer Anforderungen oder in einem Vertrag zwischen relevanten Parteien verwenden.
Fall 4
Die Festlegung eines Rahmens für Herstellungs- und Berichtsverfahren nach einem Qualitätsstandard, der insbesondere als Grundlage für die Risikobewertung geklebter Strukturen geeignet ist.

Adhésifs - Lignes directrices pour la fabrication des structures collées par adhésifs et procédures pour l'établissement de rapports pour l'évaluation des risques liés à ces structures (ISO 21368:2022)

Le présent document apporte des lignes directrices pour décrire les exigences de qualité d'assemblage par collage pour les entreprises utilisant des adhésifs et l'assemblage par collage comme moyen d'assemblage. En particulier, les lignes directrices définissent différentes approches pour parvenir aux exigences de qualité pour les procédures de fabrication et d'établissement de rapports, à la fois dans les ateliers et sur site. Elles ont pour objet de sensibiliser à l'importance de l'application de normes de qualité dans les procédures de fabrication et d’établissement de rapports, de conserver des enregistrements et de permettre ainsi à la documentation de procurer les fondements de l'évaluation du risque des structures collées lors de leur utilisation.
Ces lignes directrices ont été préparées de sorte que:
a)       elles ne dépendent pas du type de structure collée;
b)       elles ne dépendent pas des recommandations des entreprises utilisatrices et du fournisseur de l'adhésif;
c)        elles définissent les exigences de qualité pour les procédures de fabrication et d'établissement de rapports des assemblages par collage, à la fois dans les ateliers et sur site;
d)       elles peuvent servir de base à l'évaluation du risque des structures collées au cours de leur utilisation;
e)       elles peuvent servir de fondement à l'évaluation de la capacité d'un fabricant à produire des structures collées répondant aux exigences de qualité spécifiées lorsqu'elles sont détaillées dans au moins un des documents suivants:
—     un contrat entre les parties impliquées;
—     une norme d'application;
—     une réglementation.
Les lignes directrices contenues dans le présent document peuvent être adoptées en tout ou partie, au choix de l'utilisateur de l'adhésif, pour convenir à la structure en question. Les lignes directrices fournissent un cadre souple pour le contrôle des activités d'assemblage par collage dans les cas suivants.
Cas 1
L'apport d'exigences spécifiques pour le collage dans des contrats qui nécessitent que l'utilisateur de l'adhésif ait un système qualité autre que l'ISO 9001.
Cas 2
L'apport d'exigences spécifiques pour le collage comme lignes directrices pour un utilisateur d'adhésif mettant au point un système qualité.
Cas 3
L'apport d'exigences spécifiques comme référence dans des normes d'application qui utilisent le collage dans leurs exigences ou dans un contrat entre les parties concernées.
Cas 4
L'apport d'un cadre pour les procédures de fabrication et d’établissement de rapports d'une norme de qualité capable, en particulier, de servir de base à l'évaluation du risque des structures collées.

Lepila - Smernice za izdelavo lepljenih konstrukcij in postopki poročanja, primerni za oceno tveganja pri takšnih konstrukcijah (ISO 21368:2022)

Ta dokument podaja smernice, ki opisujejo zahteve glede kakovosti lepljenja, primerne za uporabo v podjetjih uporabnikov lepil, ki uporabljajo lepljenje kot način izdelave. Smernice zlasti določajo različne pristope k izpolnjevanju zahtev glede kakovosti za postopke izdelave in poročanja, tako v delavnicah kot na mestu uporabe. Namen teh smernic je predstaviti pomen ohranjanja standardov kakovosti v postopkih izdelave in poročanja, vodenja evidenc in s tem omogočanja dokumentacije, ki zagotavlja osnovo za oceno tveganja lepljenih konstrukcij v obratovanju in uporabi.
Te smernice so bile pripravljene tako, da:
a) so neodvisne od vrste lepljene konstrukcije;
b) so neodvisne od priporočil za izdelke podjetij uporabnikov lepil in dobaviteljev;
c) določajo zahteve glede kakovosti za lepljenje v smislu postopkov izdelave in poročanja, tako v delavnicah kot na mestu uporabe;
d) se lahko uporabijo kot podlaga za oceno tveganja lepljenih konstrukcij v obratovanju in uporabi;
e) se lahko uporabijo kot podlaga za ocenjevanje proizvajalčeve zmožnosti za izdelavo lepljenih konstrukcij, ki izpolnjujejo določene zahteve glede kakovosti, kadar so podrobno opisane v:
– pogodbi med obema strankama;
– standardu uporabe;
– regulativni izjavi.
Smernice v tem dokumentu se lahko sprejmejo v celoti ali pa jih lahko uporabnik lepil selektivno izbere v skladu z zadevno konstrukcijo. Smernice zagotavljajo prilagodljiv okvir za nadzor dejavnosti lepljenja v naslednjih primerih:
Primer 1
Zagotavljanje posebnih zahtev za lepljenje v pogodbah, ki zahtevajo, da ima uporabnik lepil vzpostavljen sistem kakovosti, ki ni ISO 9001.
Primer 2
Zagotavljanje posebnih zahtev za lepljenje kot vodila za uporabnika lepil, ki razvija sistem kakovosti.
Primer 3
Zagotavljanje posebnih zahtev za sklicevanja v standardih uporabe, ki uporabljajo lepljenje kot del svojih zahtev ali v pogodbi med ustreznima strankama.
Primer 4
Zagotavljanje okvira za izdelavo in postopke poročanja v skladu s standardom kakovosti, ki je primeren zlasti kot podlaga za oceno tveganja pri lepljenih konstrukcijah.

General Information

• Status: Published
• Public Enquiry End Date: 18-Jul-2023
• Publication Date: 18-Sep-2023
• ICS: 83.180 - Adhesives
• Technical Committee: IPMA - Polimer materials and products
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 18-Sep-2023
• Due Date: 23-Nov-2023
• Completion Date: 19-Sep-2023
• Ref Project: EN ISO 21368:2023 - Adhesives - Guidelines for the fabrication of adhesively bonded structures and reporting procedures suitable for the risk evaluation of such structures (ISO 21368:2022)

Overview - EN ISO 21368:2023 (Adhesives)

EN ISO 21368:2023 (ISO 21368:2022) provides guidelines for fabrication and reporting procedures for adhesively bonded structures, with the explicit aim of enabling reliable risk evaluation in service and in use. The standard is independent of adhesive type and supplier recommendations and can be adopted fully or selectively by adhesive user‑companies. It applies to both workshop and on‑site fabrication and establishes a flexible framework for quality control, documentation and assessment of a fabricator’s capability.

Key topics and technical requirements

The standard is organized around core elements and practical production topics. Key areas include:

• Classification of adhesively bonded joints by safety requirements and documentation of safety classes.
• Adhesive bonding personnel (ABP): roles, duties and defined competence levels for operators, coordinators and inspection/testing staff.
• Design and verification of adhesively bonded joints: design considerations, adherends, adhesive selection, surface treatment and verification methods (e.g., load assessment, component testing, documented experience).
• Workmanship and process control: production planning, process design, production aids and tooling, work station preparation, acclimatisation of materials, and checks before production.
• Materials handling and environment: transport, storage, logistics for adhesives and adherends, production environment controls and health & safety.
• Application procedures: dosing, mixing, application, joining, fixing and adhesive solidification controls.
• Inspection, testing and reporting procedures to maintain records that support risk evaluation and traceability.
• Contracts and subcontracting: procurement documentation, selection and management of external suppliers or subcontractors.

These topics emphasize documentation, record keeping and reproducible fabrication procedures as the basis for risk assessment.

Practical applications and who uses it

EN ISO 21368 is intended for organizations that use adhesive bonding as a fabrication method, including:

• Fabricators and manufacturers using structural adhesives (aerospace, automotive, marine, composites, construction).
• Quality managers and engineers developing or auditing adhesive bonding quality systems.
• Procurement and contract authors specifying bonding quality and reporting requirements.
• Regulators, certification bodies and asset owners performing risk evaluation or accepting bonded structures.

Use cases include: specifying bonding requirements in contracts, developing a quality system (beyond ISO 9001), referencing bonding requirements in application standards, and establishing a framework for risk‑based acceptance of bonded components.

Related standards

• Aligns with general quality management systems (e.g., ISO 9001) when detailing organizational quality requirements.
• Can be used alongside application standards or regulatory statements that specify performance or safety criteria.

For implementation, consult the full EN ISO 21368 text for detailed procedures, competence matrices and verification methods before applying in critical or safety‑sensitive applications.

Standards Content (Sample)

SLOVENSKI STANDARD
01-november-2023
Lepila - Smernice za izdelavo lepljenih konstrukcij in postopki poročanja, primerni
za oceno tveganja pri takšnih konstrukcijah (ISO 21368:2022)
Adhesives - Guidelines for the fabrication of adhesively bonded structures and reporting
procedures suitable for the risk evaluation of such structures (ISO 21368:2022)
Klebstoffe - Richtlinien für die Herstellung geklebter Strukturen und Berichtsverfahren,
die für die Risikobewertung solcher Strukturen geeignet sind (ISO 21368:2022)
Adhésifs - Lignes directrices pour la fabrication des structures collées par adhésifs et
procédures pour l'établissement de rapports pour l'évaluation des risques liés à ces
structures (ISO 21368:2022)
Ta slovenski standard je istoveten z: EN ISO 21368:2023
ICS:
83.180 Lepila Adhesives
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 21368
EUROPEAN STANDARD
NORME EUROPÉENNE
August 2023
EUROPÄISCHE NORM
ICS 83.180
English Version
Adhesives - Guidelines for the fabrication of adhesively
bonded structures and reporting procedures suitable for
the risk evaluation of such structures (ISO 21368:2022)
Adhésifs - Lignes directrices pour la fabrication des Klebstoffe - Richtlinien für die Herstellung geklebter
structures collées par adhésifs et procédures pour Strukturen und Berichtsverfahren, die für die
l'établissement de rapports pour l'évaluation des Risikobewertung solcher Strukturen geeignet sind (ISO
risques liés à ces structures (ISO 21368:2022) 21368:2022)
This European Standard was approved by CEN on 24 August 2023.

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 21368:2023 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
The text of ISO 21368:2022 has been prepared by Technical Committee ISO/TC 61 "Products” of the
International Organization for Standardization (ISO) and has been taken over as EN ISO 21368:2023 by
Technical Committee CEN/TC 193 “Adhesives” the secretariat of which is held by UNE.
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 February 2024, and conflicting national standards
shall be withdrawn at the latest by August 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 21368:2022 has been approved by CEN as EN ISO 21368:2023 without any modification.

INTERNATIONAL ISO
STANDARD 21368
Second edition
2022-03
Adhesives — Guidelines for the
fabrication of adhesively bonded
structures and reporting procedures
suitable for the risk evaluation of such
structures
Adhésifs — Lignes directrices pour la fabrication des structures
collées par adhésifs et procédures pour l'établissement de rapports
pour l'évaluation des risques liés à ces structures
Reference number
ISO 21368:2022(E)
ISO 21368:2022(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 21368:2022(E)
Contents Page
Foreword . vi
Introduction .vii
1 Scope . 1
2 Normative references . 2
3 Terms and definitions . 2
4 Core element 1: Classification of adhesively bonded joints according to safety
requirements . 9
4.1 General . 9
4.2 Definition of safety classes . 10
4.3 Documentation of the classification according to safety classes . 11
5 Core element 2: Adhesive bonding personnel (ABP)— Competences, knowledge
and experiences .11
5.1 General . 11
5.2 Adhesive bonding operators (ABO) .12
5.2.1 General .12
5.2.2 Functions . 12
5.2.3 Duties .12
5.2.4 Competences, knowledge and experiences .12
5.3 Adhesive bonding coordinator (ABC) . 13
5.3.1 General .13
5.3.2 Functions . 13
5.3.3 Duties .13
5.3.4 Competences .15
5.3.5 Organizational integration of adhesive bonding coordination.15
5.4 Levels of competences, knowledge and experiences for adhesive bonding
personnel (ABP) . . . 16
5.4.1 General . 16
5.4.2 Requirements for each level of competences, knowledge and experiences . 16
5.5 Assignment of the three competence levels to the safety classes depending on the
respective scope of work — Correlation of the core elements . 18
5.6 Comparability of competences, knowledge and experience . 19
5.7 Monitoring, inspection and testing personnel . 19
6 Core element 3: Design and verification of adhesively bonded joints .19
6.1 General . 19
6.2 Assignment to safety classes . 19
6.3 Requirements to be met by the adhesively bonded joints . 20
6.4 Design of adhesively bonded joints . 20
6.5 Adherends . 20
6.6 Adhesive . 20
6.7 Surface treatment . 21
6.8 Factors affecting the adhesive bonding process . 21
6.9 Verification . . 21
6.9.1 General . 21
6.9.2 Method 1 — Load in use < maximum load capacity . 21
6.9.3 Method 2 — Component testing . 22
6.9.4 Method 3 — Documented experience . 22
6.9.5 Method 4 — Combination of methods 1 to 3 .22
7 Drafting contracts and subcontracting (outsourcing) .22
7.1 General .22
7.2 Subcontracting (Outsourcing) . 23
7.2.1 General .23
7.2.2 Deciding on subcontracting . . 24
iii
ISO 21368:2022(E)
7.2.3 Details and documentation of procurement . 24
7.2.4 Selection of external service provider (subcontractor/supplier) and
contracting . 24
7.2.5 Management of external service providers (subcontractors/suppliers) .25
8 Workmanship .25
8.1 General . 25
8.2 General process requirements . 25
8.2.1 Production planning . 25
8.2.2 Process design .25
8.2.3 Planning the use of production aids and tools . 26
8.2.4 Production documents . 27
8.2.5 Process approval . 27
8.2.6 Transport, storage and logistics for adhesives, auxiliary materials and
adherends . 27
8.2.7 Production environment .28
8.2.8 Materials .29
8.2.9 Preparation of work stations and acclimatization of materials .29
8.2.10 Health and safety and environmental protection .30
8.2.11 Checking for fitting accuracy concerning shape, position and dimension .30
8.2.12 Checks prior to start of production .30
8.2.13 Treatment of the adherend surfaces . 31
8.2.14 Dosing, mixing and application . 32
8.2.15 Inspection and testing during adhesive bonding and adhesive solidification .33
8.2.16 Joining the adherends .33
8.2.17 Fixing .34
8.2.18 Solidification of the adhesive .34
8.2.19 Inspection and testing of finished components. 35
8.2.20 Packaging and transport of adhesively bonded components . 35
8.3 Work instructions: minimum requirements . 35
8.4 Process reliability . 37
8.4.1 General . 37
8.4.2 Quality planning . 37
8.4.3 Control of planning and manufacturing documents . 37
8.4.4 Process validation . 37
8.4.5 Production-accompanying work samples as proof of application quality .38
8.4.6 Quality control of process reliability/traceability .39
8.4.7 Instruction of adhesive bonding personnel (ABP) .40
8.4.8 Post-adhesive bonding finishing .40
8.5 Rework .40
8.6 Quality assurance .40
8.6.1 General .40
8.6.2 Quality planning .40
8.6.3 Quality inspection . 41
8.6.4 Action in the case of deviations . 41
8.6.5 Monitoring of measuring and test equipment and of production aids and
tools . . 42
8.6.6 Imperfections in adhesively bonded joints . 42
8.6.7 Control of non-conforming products . 43
8.6.8 Preventive and corrective action . 43
9 Maintenance and repair .43
9.1 General . 43
9.2 Planning of maintenance and repair . 43
9.3 Maintenance and repair instructions .44
9.4 Performing maintenance work/execution rules .44
9.5 Documentation . 45
9.6 Sub-contracting . 45
Annex A (informative) Assistance for providing adhesive bonding technology competences .46
iv
ISO 21368:2022(E)
Annex B (informative) Requirements .63
Annex C (informative) Guideline for the implementation of the design of adhesively bonded
joints and its verification .64
Annex D (informative) Criteria for choosing an adhesive bonding system .83
Annex E (informative) Description of non-destructive and destructive testing methods .86
Annex F (informative) Description of accelerating ageing tests .89
Annex G (informative) Examples of non-decorative and decorative imperfections of
adhesive bonds .93
Annex H (informative) Example of a job history sheet .95
Annex I (informative) Notes on quality planning.96
Bibliography .98
v
ISO 21368:2022(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 61, Plastics, Subcommittee SC 11,
Products.
This second edition cancels and replaces the first edition (ISO 21368:2005), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— broadening of the terms and definitions to include relevant processing and manufacturing terms;
— classification of adhesively bonded joints according to safety requirements;
— clarification of the competences, knowledge and experience of adhesive bonding personnel;
— comprehensive explanation the design of adhesively bonded joints;
— thorough description of surface treatment procedures;
— extensive account of how to assemble/manufacture of adhesively bonded joints.
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.
vi
ISO 21368:2022(E)
Introduction
Adhesive bonding technology is used widely internationally to fabricate many of the structures in
the adhesive-using industry. In some companies, it is the key feature to production. Such structures
range from microelectronic encapsulation to the structure and reinforcement of aircraft wings and
bridges. Adhesive bonding technology appeals to industry across sectors and applications because it
allows flexibility in the selection of materials, product design and product manufacture up to the final
assembly. As such, adhesive bonding technology exerts a profound influence on the cost of fabrication
and the quality of the product, thus allowing significant production savings and a competitive
advantage in comparison with traditional methods of manufacture. It is important, therefore, to ensure
that adhesive bonding technology is carried out in the most effective way and that appropriate control
is exercised over all aspects of the operation. If used properly and professionally, the adhesive bonding
technology is undoubtedly able to meet the requirements of circular economy and eco-design.
Within the ISO 9000 series of standards for quality systems, adhesive bonding technology is to be
treated as a “special process” since adhesively bonded joints cannot be fully verified by subsequent
inspection and testing of the product to ensure the required quality standards have been met.
As per today’s knowledge, adhesively bonded joints cannot be inspected into a product. The task is
to install them faultlessly from the outset. Even the most extensive and sophisticated non-destructive
testing does not improve the quality of adhesively bonded joints.
For adhesively bonded structures to be effective and fit for purpose in service, there is a need to provide
controls from the design stage through material selection to manufacture and subsequent inspection.
Poor design for adhesive bonding creates serious risks and costly difficulties in the workshop, on site
or in service. Inadequate consideration of the materials to be adhesively bonded and the choice of
adhesive may result in adhesive bonding problems such as lack of adhesion or inadequate gap-filling of
the structure. It is therefore essential for adhesive bonding procedures to be correctly formulated and
approved to avoid imperfections. Comprehensive and qualified supervision ensures that the specified
quality is achieved.
To ensure the quality of adhesively bonded structures on an international level and to make the quality
of adhesively bonded structures internationally comparable, the task of management is to:
— identify possible sources of error;
— create organizational structures that prevent these sources of error from the outset; and
— introduce suitable quality procedures.
For these reasons, this document represents the state of the art for the professional organization of
adhesive bonding processes in all areas of industry and trade in a holistic and international view. It
also applies analogously to sealing processes if the function of the seal is only to secure and support
adhesively bonded joints. The consideration of adhesive bonding technology according to this document
comprises, starting with the first idea, the development of adhesively bonded joints (pre-production),
continues through production, i.e. the manufacture of adhesively bonded joints (in-production), to the
finished adhesively bonded product including its maintenance, repair and disposal (post-production).
This holistic approach also includes the quality assurance of production, inspection and maintenance,
including the repair and disposal of adhesively bonded joints. The approach according to this document
is, without exception and in any case, independent of the lot size as well as the respective area of
application.
This document establishes definitions and sets out organizational, management technical, contractual
and technical principles to be followed when manufacturing adhesively bonded joints. This is achieved
by defining three essential core elements:
— Core element 1: the classification of each adhesive bond according to safety requirements (see
Clause 4);
vii
ISO 21368:2022(E)
— Core element 2: the appointment of supervisory personnel [Adhesive Bonding Coordinators (ABCs)]
and execution personnel (Adhesive Bonding Operators) who are both capable of objectively verifying
the necessary and required adhesive bonding competence, knowledge and experience in each case
(see Clause 5);
— Core element 3: the verification that the real load of the respective adhesive bond in the use and
application of the adhesively bonded product is in any case less than the maximum load bearing
capacity (see Clause 6).
The above-mentioned, necessary worldwide comparability in quality and implementation is achieved
through a uniform implementation of these three core elements at the international level.
Since the all numerical values described in this document are reference values, it is advisable for the
practitioners to decide on their own when implementing them.
viii
INTERNATIONAL STANDARD ISO 21368:2022(E)
Adhesives — Guidelines for the fabrication of adhesively
bonded structures and reporting procedures suitable for
the risk evaluation of such structures
1 Scope
This document provides guidelines describing the adhesive bonding quality requirements suitable for
use by adhesive user-companies utilizing adhesive bonding as a means of fabrication. In particular,
the guidelines define various approaches to meeting quality requirements for fabrication and
reporting procedures, both in workshops and on site. These guidelines aim to convey the importance
of maintaining quality standards in fabrication and reporting procedures, keeping records and thus
enabling documentation to provide the basis for risk evaluation of adhesively bonded structures in
service and in use.
These guidelines have been prepared such that:
a) they are independent of the type of adhesively bonded structure;
b) they are independent of adhesive user-companies’ and suppliers’ product recommendations;
c) they define the quality requirements for adhesive bonding in terms of fabrication and reporting
procedures, both in workshops and on site;
d) they can be used as the basis for risk evaluation of adhesively bonded structures in service and in
use;
e) they can be used as a basis for assessing a fabricator's capability to produce adhesively bonded
structures fulfilling specified quality requirements when they are detailed in one or more of the
following:
— a contract between the parties involved;
— an application standard;
— a regulatory statement.
The guidelines contained within this document can be adopted in full or selectively chosen by the
adhesive user to suit the structure concerned. The guidelines provide a flexible framework for the
control of adhesive bonding activities in the following cases.
Case 1
The provision of specific requirements for adhesive bonding in contracts that require the adhesive user
to have a quality system other than ISO 9001.
Case 2
The provision of specific requirements for adhesive bonding as guidance to an adhesive user developing
a quality system.
Case 3
The provision of specific requirements for references in application standards that uses adhesive
bonding as part of its requirements or in a contract between relevant parties.
ISO 21368:2022(E)
Case 4
The provision of a framework for fabrication and reporting procedures to a quality standard, suitable
in particular as a basis for the risk evaluation of adhesively bonded structures.
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 472, Plastics — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 472 and the following 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 https:// www .electropedia .org/
3.1
adherend
substrate
object or semi-finished product (for example, sheet metal, wires, metal extruded, moulded plastic,
fabrics, glass, etc.) on which an adhesive is applied
Note 1 to entry: In adhesive bonding processes, the term adherend is often used as a synonym for substrate.
3.2
adhesion
interaction between the adhesive and the adherend/substrate (3.1) surface
Note 1 to entry: The interactions that make up adhesion are based on forces between the surface of the adherend/
substrate and the adhesive film and include physical interactions, chemical bonds and micromechanical
interlocking.
Note 2 to entry: Adhesion occurs in nm-dimensions.
3.3
adhesion promotor
primer
liquid used in surface treatment to improve the adhesion of the adhesive to the substrate/adherend (3.1)
Note 1 to entry: Adhesion promotors often are named as primers, accelerators or activators.
3.4
adhesive
non-metallic material, which joins two adherends/substrates (3.1) together via adhesion and cohesion
3.5
adhesive bonding
special process for joining of adherends/substrates (3.1) by using an adhesive
Note 1 to entry: The adherends/substrates can be made of the same as well as of different materials and can have
different surface characteristics.
ISO 21368:2022(E)
3.6
adhesive bonding area
area used to join two adherends/substrates (3.1) using an adhesive
Note 1 to entry: Usually the product of the overlap length and overlap width of the adherends/substrates.
3.7
adhesive bonding coordinator
ABC
responsible adhesive bonding coordinator
rABC
competent person with proven professional skills in adhesive bonding technology responsible for
the supervision and release of the adhesive bonding processes and for all activities associated with it
including the release
Note 1 to entry: The responsible adhesive coordinator (rABC) is the appointed head of all adhesive bonding
processes including their release and with the appropriate decision-making managerial authority concerning the
adhesive technology within the company.
3.8
adhesive bonding operator
ABO
execution personnel with proven corresponding knowledge applying or executing independently the
adhesive bonding process to manufacture, maintain or repair components according to approved work
instructions
3.9
adhesive bonding personnel
ABP
people involved in the design, planning, manufacturing, quality assurance and maintenance/repair
related to the adhesive bonding process
Note 1 to entry: As a rule, this employee group consists of ABCs (3.7) and ABOs (3.8).
3.10
adhesive bonding procedure
all processes concerned with adhesive bonding such as surface treatment, processing the adhesive,
application of the adhesive, joining the adherends/substrates (3.1), and solidification (curing/hardening)
3.11
adhesive bonding surface
area prepared for adhesive bonding, or on which the adhesive is applied, or the surface of the part to be
adhesively bonded with adhesive between two parts to be adhesively bonded [length of overlap × width
of overlap mm)]
3.12
adhesively bonded joint
connection of two or more substrates (adherends) from the same material or different materials with
the use of an adhesive
Note 1 to entry: An adhesively bonded joint can be defined as rigid coupling, flexible coupling or joint sealing. All
three types of junction are based on the same principles of operation.
3.13
adhesively bonded structure
structure
structure used for a partially or fully finished constituent or any other form of adhesively bonded item
and designed mainly to transmit mechanical loads
Note 1 to entry: The loadbearing function is the main role of the adhesively bonded item ensuring reliability and
fitness-for-purpose throughout the life cycle of the finished product.
ISO 21368:2022(E)
3.14
adhesive tape
flexible backing or carrier coated with a pressure-sensitive, moisture- or heat-activated adhesive
3.15
ageing
entirety of all irreversible chemical and physical processes occurring in a material in the course of time
Note 1 to entry: This can relate to:
— evolution of the properties of adhesively bonded joints with time;
— reproduction of the real operating life through accelerating (reduce time) test of ageing in appropriated
environment (chemical and mechanical).
3.16
application
placement of the adhesive during the adhesive bonding procedure
3.17
assembly
group of parts that has been placed together for adhesive bonding or has been adhesively bonded
3.18
clamping
holding of an adhesively bonded joint under pressure with clamps during solidification of the adhesive
between the adherends
3.19
cohesion
internal strength that, for example, keep the molecules of an adhesive together
Note 1 to entry: These forces are based on attractive physical forces between the polymer chains, entanglement
of the polymer chains, and chemical bonds inside and between the adhesive polymer chains.
3.20
component
one part of an adhesive system
Note 1 to entry: In adhesive bonding technology, the parts of an adhesive system (resin and hardener) are called
components (component A and component B).
3.21
conditioning
exposure of components (3.20) and joining parts required for the adhesive bonding process for a
reasonable period in compliance with the specified requirements
3.22
curing
chemical solidification of the adhesive
Note 1 to entry: Chemical reactions leading to solidification of the adhesive in the form of thermoplastic,
elastomeric or thermoset polymers.
Note 2 to entry: This refers to chemically curing adhesives.
3.23
curing time
period of time required to solidify an adhesive curing (3.22) by chemical reactions
ISO 21368:2022(E)
3.24
destructive testing
analyses, tests and surveys carried out for the definition of information of qualitative/quantitative
about specific propert
...