ISO 7913:1994

Aerospace - Bolts and screws, metric - Tolerances of form and position

Cancels and replaces the first edition (1985). Specifies the tolerances of form and position applicable to all types of metric bolts and screws in the nominal thread diameter range 3 mm to 24 mm used in aerospace construction. Intended for the drawing up of aerospace product standards.

Aéronautique et espace — Vis métriques — Tolérances de forme et de position

General Information

• Status: Published
• Publication Date: 12-Oct-1994
• ICS: 49.030.20 - Bolts, screws, studs
• Technical Committee: ISO/TC 20/SC 4 - Aerospace fastener systems
• Drafting Committee: ISO/TC 20/SC 4 - Aerospace fastener systems
• Current Stage: 9093 - International Standard confirmed
• Start Date: 19-Oct-2021
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 7913:1985 - Aerospace - Fasteners - Tolerances of form and position for bolts and screws
• Effective Date: 15-Apr-2008

Overview

ISO 7913:1994 - "Aerospace - Bolts and screws, metric - Tolerances of form and position" is an international standard that defines geometric tolerances applicable to metric bolts and screws used in aerospace construction. This second edition (1994) cancels and replaces ISO 7913:1985 and applies to nominal thread diameters from 3 mm to 24 mm. Tolerance values are expressed in millimetres and the standard is intended primarily for preparing aerospace product standards and technical drawings.

Key topics and technical requirements

• Scope: Form and position tolerances for all types of metric bolts and screws used in aerospace applications with nominal thread diameters 3–24 mm.
• Tolerance types covered (portrayals conform to ISO 1101 and ISO 2692):
  • Perpendicularity of bolt underhead bearing surface
  • Straightness of total bolt shank length
  • Run-out (radial run-out) of external flange and wrenching diameters for bihexagonal, spline and hexagonal heads
  • Run-out of width across corners for hexagonal heads
  • Position of split-pin and locking-wire holes (in thread and head)
  • Run-out of conical or cylindrical portions of pan and countersunk head bolts
  • Perpendicularity and concavity at the top of countersunk heads
• Tolerance values: Numeric limits are provided in a table (Table 2) for short/medium/long thread lengths and threaded-to-head conditions. Parameter “V” is dimensionless (mm/mm).
• Normative references: The standard references ISO 1101 (geometrical tolerancing/GD&T) and ISO 2692 (maximum material principle), so geometric dimensioning and tolerancing (GD&T) conventions apply.

Applications and who uses it

ISO 7913 is used where precise geometric control of fasteners affects assembly, fit, function or safety in aerospace systems. Typical users include:

• Aerospace designers and mechanical engineers specifying bolt/screw tolerances on drawings
• Fastener manufacturers and suppliers producing aerospace-grade bolts and screws
• Quality assurance and inspection teams applying measurement criteria for form and position
• Procurement and standards writers aligning product standards to international requirements
• Maintenance, repair and overhaul (MRO) organizations verifying replacement fasteners

Practical benefits include consistent manufacturing tolerances, improved interchangeability, reduced assembly issues, and clear inspection criteria for critical aerospace applications.

Related standards

• ISO 1101: Geometrical tolerancing - form, orientation, location and run-out (GD&T)
• ISO 2692: Geometrical tolerancing - Maximum material principle

Keywords: ISO 7913, aerospace bolts, metric bolts and screws, form and position tolerances, geometric tolerancing, GD&T, fastener tolerances, aerospace standards.

Standards Content (Sample)

ISO
INTERNATIONAL
STANDARD
Second edition
Deuxieme Edition
NORME
1994-11-01
INTERNATIONALE
Bolts and screws, metric -
Aerospace -
Tolerantes of form and Position
Abronautique et espace - Vis metriques -
Tolhrances de forme et de Position
Reference number
Numkro de r6ftirence
ISO 7913: 1994( E/F)
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 committes. Esch 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.
Draft International Standards adopted by the technical committees
are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the
member bodies casting a vote.
International Standard ISO 7913 was prepared by Technical Com-
mittee lSO/TC 20, Aircraft and space vehicles, Subcommittee SC 4,
Aerospace fastener Systems.
This second edition cancels and replaces the first edition (ISO
7913:1985), of which it constitutes a technical revision.
@ISO 1994
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronie or mechanical, including photocopying and
microfilm, without Permission in writing from the publisher. / Droits de reproduction reserves.
Sauf prescription differente, aucune Partie de cette publication ne peut etre reproduite ni
utilisee sous quelque forme que ce soit et par aucun procede, electronique ou mecanique, y
compris Ia photocopie et les microfilms, sans I ’accord k-it de I ’editeur.
International Organization for Standardization
56 l CH-121 1 Geneve 20 l Switzerland
Case postale
@ ISO ISO 7913:1994(E/F)
Avant-propos
L ’ISO (Organisation internationale de normalisation) est une
federation mondiale d ’organismes nationaux de normalisation
(comites membres de WO). L ’elaboration des Normes inter-
nationales est en general confiee aux comites techniques de I ’ISO.
Chaque comite membre interesse par une etude a Ie droit de faire
Partie du comite technique cr& a cet effet. Les organisations
internationales, gouvernementales et non gouvernementales, en
liaison avec I ’ISO participent egalement aux travaux. L ’ISO collabore
etroitement avec Ia Commission electrotechnique internationale
(GEI) en ce qui concerne Ia normalisation electrotechnique.
Les projets de Normes internationales adoptes par les comites
techniques sont soumis aux comites membres pour vote. Leur
publication comme Normes internationales requiert I ’approbation de
75 % au moins des comites membres votants.
Le Norme internationale ISO 7913 a etc elaboree par Ie comite
technique lSO/TC 20, Akonautique et espace, sous-comite SC 4,
hments de fixation pour constructions akospatiales.
Cette deuxieme edition annule et remplace Ia premiere edition
(ISO 7913:1985), d on t e II e constitue une revision technique.
. . .
Ill
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INTERNATIONAL STANDARD
@ ISO ISO 7913:1994(E/F)
NORME INTERNATIONALE
Aerospace - Bolts and Ahonautique et espace -
screws, metric - Vis metriques -
Tolerantes of form and Tokrances de forme et de
Position
Position
1 Scope
1 Domaine d ’application
This International Standard specifies the La presente Norme internationale prescrit les
tolerantes of form and Position applicable to all tolerantes de forme et de Position applicables a
types of metric bolts and screws in the nominal tous les types de vis metriques de Ia gamme de
thread diameter range 3 mm to 24 mm used in diametres nominaux de filetage 3 mm a 24 mm
aerospace construction. destinees aux constructions aerospatiales.
La presente Norme internationale est applicable a
lt is intended for the drawing up of aerospace
I ’elaboration de normes de produit destinees aux
product Standards.
constructions aerospatiales.
2 Rhfbrences normatives
2 Normative references
The following Standards contain provisions Les normes suivantes contiennent des disposi-
which, through reference in this text, constitute tions qui, par Suite de Ia reference qui en est faite,
provisions of this International Standard. At the constituent des dispositions valables pour Ia
time of publication, the editions indicated were presente Norme internationale. Au moment de Ia
valid. All Standards are subject to revision, and publication, les editions indiquees etaient en
Parties to agreements based on this International vigueur. Toute norme est sujette a revision et les
Parties prenantes des accords fondes sur Ia
Standard are encouraged to investigate the possi-
presente Norme internationale sont invitees a
bility of applying the most recent editions of the
rechercher Ia possibilite d ’appliquer les editions
Standards indicated below. Members of IEC and
les plus recentes des normes indiquees ci-apres.
ISO maintain registers of currently valid Inter-
Les membres de Ia CEI et de I ’ISO possedent Ie
...