SIST EN ISO 16047:2005

SLOVENSKI STANDARD
SIST EN ISO 16047:2005
01-maj-2005
Vezni elementi – Preskus torzijskega momenta/prednapetosti (ISO 16047:2005)
Fasteners - Torque/clamp force testing (ISO 16047:2005)
Verbindungselemente - Drehmoment/Vorspannkraft-Versuch (ISO 16047:2005)
Eléments de fixation - Essais couple/tension (ISO 16047:2005)
Ta slovenski standard je istoveten z: EN ISO 16047:2005
ICS:
21.060.01 Vezni elementi na splošno Fasteners in general
SIST EN ISO 16047:2005 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 16047:2005

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SIST EN ISO 16047:2005
EUROPEAN STANDARD
EN ISO 16047
NORME EUROPÉENNE
EUROPÄISCHE NORM
February 2005
ICS 21.060.01
English version
Fasteners - Torque/clamp force testing (ISO 16047:2005)
Eléments de fixation - Essais couple/tension (ISO Verbindungselemente - Drehmoment/Vorspannkraft-
16047:2005) Versuch (ISO 16047:2005)
This European Standard was approved by CEN on 17 January 2005.
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 Central Secretariat 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 Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2005 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 16047:2005: E
worldwide for CEN national Members.

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SIST EN ISO 16047:2005

EN ISO 16047:2005 (E)





Foreword


This document (EN ISO 16047:2005) has been prepared by Technical Committee ISO/TC 2
"Fasteners" in collaboration with Technical Committee CEN/TC 185 "Threaded and non-
threaded mechanical fasteners and accessories", the secretariat of which is held by DIN.

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 August 2005, and conflicting national
standards shall be withdrawn at the latest by August 2005.

According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary,
Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.


Endorsement notice

The text of ISO 16047:2005 has been approved by CEN as EN ISO 16047:2005 without any
modifications.

2

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SIST EN ISO 16047:2005

INTERNATIONAL ISO
STANDARD 16047
First edition
2005-02-01

Fasteners — Torque/clamp force testing
Éléments de fixation — Essais couple/tension




Reference number
ISO 16047:2005(E)
©
ISO 2005

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SIST EN ISO 16047:2005
ISO 16047:2005(E)
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©  ISO 2005
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ii © ISO 2005 – All rights reserved

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SIST EN ISO 16047:2005
ISO 16047:2005(E)
Contents Page
Foreword. iv
1 Scope. 1
2 Normative references . 1
3 Terms and definitions. 2
4 Symbols and their designations. 3
5 Principle of test . 4
5.1 General. 4
5.2 Determination of coefficients of friction. 4
5.3 Determination of torque coefficient K (K-factor). 5
5.4 Determination of ratio T/F. 5
6 Apparatus. 5
6.1 Testing machine. 5
6.2 Test fixture. 5
7 Test parts . 6
7.1 General. 6
7.2 Test-bearing plates or test washers. 7
7.3 Test nuts for testing bolts, screws and studs. 8
7.4 Test bolts or test screws for testing nuts. 8
8 Testing under standard conditions. 9
9 Testing under specific conditions. 9
10 Evaluation of results. 9
10.1 Determination of torque coefficient K. 9
10.2 Determination of coefficient of total friction µ . 10
tot
10.3 Determination of coefficient of friction between threads µ . 10
th
10.4 Determination of coefficient of friction between bearing surfaces µ . 11
b
10.5 Determination of yield clamp force F . 11
y
10.6 Determination of yield tightening torque T . 11
y
10.7 Determination of ultimate clamp force F . 11
u
10.8 Determination of ultimate tightening torque T . 11
u
11 Test report. 11
11.1 General. 11
11.2 Description of fasteners to be tested. 12
11.3 Description of test parts. 13
11.4 Testing machine. 13
11.5 Test fixture. 14
11.6 Environmental conditions. 14
11.7 Specific conditions . 14
11.8 Test results . 14
Bibliography . 15

© ISO 2005 – All rights reserved iii

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SIST EN ISO 16047:2005
ISO 16047:2005(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. 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.
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.
ISO 16047 was prepared by Technical Committee ISO/TC 2, Fasteners, Subcommittee SC 1, Mechanical
properties of fasteners.

iv © ISO 2005 – All rights reserved

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SIST EN ISO 16047:2005
INTERNATIONAL STANDARD ISO 16047:2005(E)

Fasteners — Torque/clamp force testing
1 Scope
This International Standard specifies the conditions for carrying out torque/clamp force tests on threaded
fasteners and related parts.
It is applicable, basically, to bolts, screws, studs and nuts made of carbon steel and alloy steel, whose
mechanical properties are specified in ISO 898-1, ISO 898-2 or ISO 898-6, having ISO metric threads with
thread sizes M3 to M39. It is also applicable to the combination of other externally and internally threaded
fasteners with a triangular ISO thread according to ISO 68-1.
It is not applicable to set screws and similar threaded fasteners that are not under tensile stresses, nor to
screws which form their own mating thread or threaded fasteners having additional self-locking features.
Unless otherwise agreed, the tests are carried out at room temperature. However, tests carried out under
standard conditions are made at a temperature of 10 °C to 35 °C.
This method allows determination of the tightening characteristics of threaded fasteners and related parts.
2 Normative references
The following referenced documents are indispensable for the application 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 68-1, ISO general purpose screw threads — Basic profile — Part 1: Metric screw threads
ISO 273:1979, Fasteners — Clearance holes for bolts and screws
ISO 898-1, Mechanical properties of fasteners made of carbon steel and alloy steel — Part 1: Bolts, screws
and studs
ISO 898-2, Mechanical properties of fasteners — Part 2: Nuts with specified proof load values — Coarse
thread
ISO 898-6, Mechanical properties of fasteners — Part 6: Nuts with specified proof load values — Fine pitch
thread
ISO 4014, Hexagon head bolts — Product grades A and B
ISO 4017, Hexagon head screws — Product grades A and B
ISO 4032, Hexagon nuts, style 1 — Product grades A and B
ISO 4033, Hexagon nuts, style 2 — Product grades A and B
ISO 4042:1999, Fasteners — Electroplated coatings
© ISO 2005 – All rights reserved 1

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SIST EN ISO 16047:2005
ISO 16047:2005(E)
ISO 4759-3:2000, Tolerances for fasteners — Part 3: Plain washers for bolts, screws and nuts — Product
grades A and C
ISO 4762, Hexagon socket head cap screws
ISO 6892, Metallic materials — Tensile testing at ambient temperature
ISO 7093-1, Plain washers — Large series — Product grade A
ISO 8673, Hexagon nuts, style 1, with metric fine pitch thread — Product grades A and B
ISO 8674, Hexagon nuts, style 2, with metric fine pitch thread — Product grades A and B
ISO 8765, Hexagon head bolts with metric fine pitch thread — Product grades A and B
ISO 15071, Hexagon bolts with flange — Small series — Product grade A
ISO 15072, Hexagon bolts with flange with metric fine pitch thread — Small series — Product grade A
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
clamp force
F
axial tension acting on the bolt shank or compression acting on the clamped member during tightening
3.2
yield clamp force
F
y
clamp force at which the bolt shank or the engaged thread yield under combined stress condition in tightening
3.3
ultimate clamp force
F
u
maximum clamp force under combined stress condition potentially induced before bolt shank fracture
3.4
tightening torque
wrenching torque
applied torque
T
overall torque applied on nut or bolt head in tightening
3.5
yield tightening torque
T
y
tightening torque with which yield clamp force is gained
3.6
thread torque
T
th
torque acting on bolt shank through mating threads during tightening
2 © ISO 2005 – All rights reserved

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SIST EN ISO 16047:2005
ISO 16047:2005(E)
3.7
bearing surface friction torque
T
b
torque acting on clamped member through bearing surfaces during tightening
3.8
ultimate tightening torque
T
u
tightening torque with which ultimate clamp force is gained
4 Symbols and their designations
See Table 1.
Table 1 — Symbols and their designations
Symbol Designation
d Nominal thread diameter
d Basic pitch diameter of thread
2
d Diameter of hole of test fixture
4
d Clearance hole diameter of washer or bearing part (nominal value)
h
D Diameter of bearing surface under nut or bolt head for friction (theoretical or measured)
b
D Outer diameter of bearing surface, d or d (see product standards)
o w min k min
Diameter of plain area of bearing plate
D
p
F Clamp force
Proof load according to ISO 898-1, ISO 898-2 or ISO 898-6, whichever is relevant
F
p
F Ultimate clamp force
u
Yield clamp force
F
y
h Thickness of test-bearing plate or test washer
T
Torque coefficient, K =
K
Fd
L Clamp length
c
L Length of complete thread between bearing surfaces
t
P Pitch of the thread
T Tightening torque
T Bearing surface friction torque
b
T Thread torque
th
T Ultimate tightening torque
u
Yield tightening torque
T
y
Θ Rotation angle
µ Coefficient of friction between bearing surfaces under nut or bolt head
b
µ Coefficient of friction between threads
th
µ Coefficient of total friction
tot
© ISO 2005 – All rights reserved 3

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SIST EN ISO 16047:2005
ISO 16047:2005(E)
5 Principle of test
5.1 General
A tightening torque is steadily applied to a bolt/nut or screw/nut assembly to generate a clamp force, and to
measure and/or determine one or more of the tightening characteristics, which can include torque coefficient,
coefficient of total friction, coefficient of friction between threads, coefficient of friction between bearing
surfaces, yield clamp force, yield tightening torque, rotation angle and ultimate clamp force. In the range of
elastic deformation, a linear relationship is assumed between torque and clamp force.
NOTE For studs, only the coefficient of friction between threads is determined.
There are two different goals for testing:
a) testing of tightening characteristics of a fastener under standard conditions (see Clause 8), i.e. with test-
bearing plates/test washers type HH or type HL as specified in 7.2.2 and 7.2.3 and with test nuts or test
bolts as specified in 7.3 and 7.4;
b) testing of tightening characteristics of fasteners under specific conditions, see Clause 9.
The relationship between tightening characteristics which may be obtained and the parameters to be
measured are shown in Table 2.
There are different methods (see 5.2 to 5.4) to describe the torque/clamp force behaviour of bolted joints with
different surface and lubrication conditions.
Table 2 — Parameters to be measured to obtain respective tightening characteristics
Parameters to be measured
Bearing
Tightening characteristics Clamp Tightening Thread surface Rotation
Clause
which may be determined
force torque torque friction angle
torque
F T T T Θ
th b
Torque coefficient, K { { — — — 10.1
Coefficient of total friction, µ { { — — — 10.2
tot
Coefficient of friction between threads, µ { — { — — 10.3
th
Coefficient of friction between bearing surfaces, µ { — — { — 10.4
b
Yield clamp force, F { — — — { 10.5
y
Yield tightening torque, T { { — — { 10.6
y
Ultimate clamp force, F { — — — — 10.7
u
Ultima
...