INTERNATIONAL
STANDARD
Second edition
1993-11-01
ISO metric trapezoidal
Tolerantes
screw threads
-
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Filetages m&t-iques trapkzoiiiaux ISO - Tokrances
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ISO 2903:1993
https://standards.iteh.ai/catalog/standards/iso/1f87f8f8-9fd6-429f-bcde-1b4c5adb5684/iso-2903-1993
Reference number
ISO 2903:1993(E)
ISO 2903:1993(E)
Contents
Page
1
Scope .. .. . . .. .. . .. .. .. . .. .. . .. . .. . .. .. . . .. . .. . .. .. . . .. .. . . .. .. .. . .. .. . .. .. .. . .. . ... .. .. .. .. .. .. . .. . 1
2
Normative references
3
Definitions
. .. . .. .. .. . .. .. . .. .. . . .. .. . . .. . .. . .. .. . . .. .. .. .. .. .. . .. .. .. . .. .. . . .. .. . .. .. .. . ... .. ... . 1
4
Symbols
.. . ... . . .. .. .. . .. .. . . .. .. . . .. .. . . .. .. . . .. .. . . .. .. . .. .. .. . .. .. . .. . .. .. . .. .. . .. .. .. . .. . 1
5
Structure of the tolerante
6
Tolerante
grades
7
Tolerante
positions
8
Lengths of thread engager ient
9
Crest and root diameter to erances
IO
Pitch diameter tolerantes
11
Recommended
12
Multiple-Start
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1
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1
.. . .. . .. . .. . .. . .. . .. .. . . . ... . . . .. ... ... .. . .. .. . ...*....................
2
System
.. . . .. .. .. .. .. . . .. .. . . .. .. .. .. .. .. .. .. .. .. .. . .. . ... .. . ... . .. .. . .. .. 2
tolerante
. . .. . .. . .. .. . .. ... . . .. .. . . .. .. .. . . .. .. ..*.......
3
. . .. ... . .. .. . .. . .. .. . .. . .. . .. .. . .. .. .. . .. . 3
. . .. . .. . .. .. . . .. .. .. . .. .. . .. .. . .. . .. .. . .. .. . .. .. .. . .. .. 3
classes
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iTeh Standards
9”
.,.................,,.............................................................
13 Formulae
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. .. .. .. . .. . .. . .. . .. . . .. . . .. .. .. .. .. .. . .. . .. .. .. .. . . .. .. . .. .. .. .. .. .. .. .. .. . . 10
14 Designation
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threads
. .. .. .. . . .. .. . . . .. .. . . .. ... . .. .. . .. .. . .. . .. .. . .. .. .. . ... . .. .. . 9
ISO 2903:1993
https://standards.iteh.ai/catalog/standards/iso/1f87f8f8-9fd6-429f-bcde-1b4c5adb5684/iso-2903-1993
0 ISO 1993
All rights reserved. No part of this publication may be reproduced or utilized in any form or
by any means, electronie or mechanical, including photocopying and microfiim, without permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-l 211 Geneve 20 l Switzerland
Printed in Switzerland
ISO 2903:1993(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.
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.
iTeh Standards
International Standard ISO 2903 was prepared by Technical Committee
(https://standards.iteh.ai)
lSO/TC 1, Screw threads, Sub-Committee SC 2, Tolerantes.
This
second
edition
cancels
and
replaces
the
first
edition
Document
Preview
(ISO
tables
and 7 of which have been technically revised.
2903:1977),
1
ISO 2903:1993
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ISO 2903:1993
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INTERNATIONAL
ISO 2903:1993(E)
STANDARD
ISO metric trapezoidal
1
-
screw threads
4
Scope
This International Standard specifies a tolerante system for metric trapezoidal screw threads in accordante with ISO 2902. The tolerantes refer to the basic
Profile ISO 2901.
The tolerante System does not apply to trapezoidal
screw threads with special requirements on axial displacement, for example lead screws.
Tolerantes
Symbols
(See figures 1 to 4)
basic major diameter of nut thread, in millimetres
4
Dl
basic minor diameter of nut thread, in millimetres
02
basic pitch diameter
of nut thread, in millimetres
d
basic major diameter of bolt thread, in millimetres
4
basic minor diameter of bolt thread, in millimetres
d2
basic pitch diameter of bolt thread, in millimetres
P
pitch, in millimetres
ph
lead, in millimetres
N
designation
“ Normal ”
for thread engagement
group
l-
designation
for thread engagement
group
iTeh Standards
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2 Normative
references
Preview
The following Standards containDocument
provisions which,
through reference in this text, constitute provisions
” Long ”
of this International Standard. At the time of publithread engagement, in millimetres
ISO 2903:1993lN
cation, the editions indicated were valid. All Standards
tolerante,
in micrometres
T
arehttps://standards.iteh.ai/catalog/standards/iso/1f87f8f8-9fd6-429f-bcde-1b4c5adb5684/iso-2903-1993
subject to revision, and Parties to agreements
based on this International Standard are encouraged
TDl
to investigate the possibility of applying the most reTDZ
cent editions of the Standards indicated below.
. tolerantes for D,, D,, d, da, dz (for D, no tolTd
Members of IEC and ISO maintain registers of curerances are specified), in micrometres
rently valid International Standards.
Td3
ISO 965-1: 1980, /SO general purpose metric screw
threads - Tolerantes - Part 1: Principles and basic
data.
Td2
ei, EI
lower deviations (EI for nut threads is equal
to Zero), in micrometres
es, ES
upper deviations,
ISO 2901: 1993, ISO metric trapezoidal screw threads
- Basic Profile and maximum material profiles.
in micrometres
ISO 2902:1977, ISO metric trapezoidal screw threads
- General plan.
ISO 5408: 1983, Cylindrical screw threads lw .
3
Vocabu-
Structure
of the tolerante
System
The System is based on the tolerante System for ISO
general-purpose metric screw threads of ISO 965-1,
completed with tolerante positions c and e, and with
values for pitches above 6 mm.
Definitions
For the purposes of this International
definitions given in ISO 5408 apply.
5
Standard, the
The recommended
tolerante classes are, however,
not the same as those for ISO metric screw threads
in ISO 965-1.
ISO 2903:1993(E)
6
Tolerante
The following
grades
tolerante
Tolerante
7
positions
Pitch line
grades are established:
Tolerante
grades
es
Minor diameter of nut threads D, :
4
Major diameter of bolt threads d :
4
Pitch diameter of nut threads D, :
7
8
9
7
8
9
7
8
9
Pitch diameter of bolt threads 4 :
Minor diameter of bolt threads 4 :
(6)
ei
Figure
Tolerante grade 6 for the pitch diameter (4) of the
bolt thread has been included only as a means to establish the pitch diameter tolerantes of grades 7, 8
and 9. See 13.4.2.
1 -
Tolerante positions with
zero line (basic size)
The following tolerante
the pitch diameter.
respect to
positions are standardized
a) For nut threads: H with zero fundamental
The tolerante grade for the minor diameter (4) of the
bolt thread is always the Same as for the pitch diameter (d,).
for
deviation
(see figure 2 and table 1).
b) For both threads: c and e with negative fundamental deviation (see figure 3 and table 1).
However, the values for Td3 and Td2 are not the same
for a same grade because Td3 = 1,25Tdz + lesl.
The tolerante Position for the minor diameter D,t and
iTeh Standards
the major diameter D, of the nut threads is always
H, i.e. with zero fundamental deviation. The tolerante
(https://standards.iteh.ai)
Position for the major diameter d and minor diameter
4 of the bolt threads is in all cases h, i.e. with zero
deviation, and it is independent of the
Documentfundamental
Preview
tolerante Position of the pitch diameter.
ISO 2903:1993
https://standards.iteh.ai/catalog/standards/iso/1f87f8f8-9fd6-429f-bcde-1b4c5adb5684/iso-2903-1993
al
Figure
01
a’
2 -
I
Nut threads
with tolerante
Position
H for the pitch diameter
0
