ISO/FDIS 25408-2

ISO/TC 17/SC 17
Secretariat: SAC
Date: 2026-06-2908-12
Testing method for bead wire – —
Part 2:
Adhesion test
Méthode d'essai pour les fils de tringle —
Partie 2: Essai d'adhérence
FDIS stage
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Contents
Foreword . iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Apparatus . 1
5.1 Tensile testing machine . 1
5.2 Vulcanization press . 2
5.3 Mould . 2
5.4 Block holder . 3
5.5 Rubber pad remover and pressure roll . 5
5.6 Solvent . 5
5.7 Rubber cutter . 6
5.8 Consumable . 6
6 Procedure . 6
6.1 Preparation for rubber compound . 6
6.2 Preparation for vulcanization mould . 7
6.3 Sample preparation . 7
6.4 Preparation of the rubber block. 7
6.5 Cleaning process . 11
6.6 Pull out test . 12
7 Calculation and report of pull-out force . 12
8 Precision and variance. 12
9 Rubber coverage rate (RCR) . 13
10 Calculation and report of rubber coverage rate (RCR) . 14

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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
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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).
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patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
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This document was prepared by Technical Committee ISO/TC 17, Steel, Subcommittee SC 17, Steel wire rod
and wire products.
A list of all parts in the ISO 25408 series can be found on the ISO website.
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.
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Testing method for bead wire – —
Part 2:
Adhesion test
1 Scope
This document specifies the test method for strength of adhesion of bead wire (round and shaped) to
vulcanized rubber compounds.
The method applies to, but is not limited to, wire made from brass, bronze, or zinc coated steel wire.
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 16650, Bead wire
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 16650 apply.
ISO and IEC maintain terminology 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/
4 Principle
Specimens of bead wire are vulcanized into a block of rubber and force necessary to pull bead wires that are
linearly out of the rubber is measured. The used clamp or block holder shall be equipped with a circle hole to
guarantee the homogenous stress. If required, the visual evaluation of rubber coverage is also determined.
5 Apparatus
5.1 Tensile testing machine
a) a) The constant-rate-of-extension (CRE) tensile testing machine capacity that the measured force
is required to fracture the wire shall be within force measurement range. The device shall be equipped
with a load and extension recorder, digital read-out, automated data logger or computer controlled tensile
test machine.
b) b) Cross-head speed: maximum speed shall be ≥ 150 mm/min. (≠ test speed)).
c) c) Machine accuracy Class 0,5 = Load weighing accuracy: +/-± 0,5 %%.
d) d) Load cell capacity depends on the type and characteristics of the wire.
5.2 Vulcanization press
a) a) The machine type of vulcanization press can be electrical or steam heat which is large enough
to take the mould dimensions and capable of a minimum pressure of 3,5 MPa over the total area of the
mould plate used.
b) b) Dimension of the press platens: minimum 400 mm x× 400 mm.
c) c) Temperature capacity: maximum 200 °C.
d) d) For a standard 1 cavity mould (50 mm embed) a pressure of 70 kN to 100 kN is to apply.
e) e) Heating for the top and the bottom platens shall be of sufficient capacity for maintaining the
mould components at the specific temperatures required for the rubber compound being used.
f) f) The heat up power of the press shall be min 10 °C/min or better 20 °C/min.
g) g) Temperature resolution: 0,5 °C.
h) h) Temperature in the rubber shall be controlled within ±2 °C during vulcanization.
5.3 Mould
a) a) Mould designed for a 13 mm thick block of rubber, 222 mm long, and 50 mm wide, with 15
wire slots across the width of the mould spaced 13 mm apart at the middle of the mould thickness, and
with top and bottom plates for the mould.
b) b) Moulds with embed lengths of 12,5 mm ,15 mm , 20 mm or 25 mm may be used, as specified
and agreed by relevant parties.
c) c) The 15 wire slots have a typical ‘Y’ shape groove for bead wire adhesion testing.
d) d) The ‘Y’ shape slot width can be according to wire thickness. Standard slot widths are 1,15 mm
and 2,1 mm and 3,1 mm. Standard depth of ‘Y’ shape slots is 7,5 mm (see Figure 1Figure 1).).
Figure 1 — Vulcanization mould
5.4 Block holder
The block holder grip shall be a special holder made for the vulcanized block sample. The opposite grip may
be any type of clamp of sufficient capacity to handle the specimen and designed to prevent its slippage in the
grip area (see Figure 2Figure 2).).
Key
NOTE 1 The dimensions all with accuracy ±0.,2 mm except where noted.
NOTE 2 Material is steel.
NOTE 3 Break all sharp corners.
Figure 2 — Block holder
5.5 Rubber pad remover and pressure roll
Rubber pad remover or manual mould ejector is recommended for safely and quickly removing of rubber
block out of the hot mould without extreme bending of the ongoing adhesion pad.
5.6 Solvent
a) a) The use of solvent on rubber surface or bead wire surface can influence the adhesion process.
b) b) Cleaning or even touching rubber surface and bead wire surface is not allowed.
c) c) Only if the requester really requires cleaning the rubber surface or the bead wire surface is it
allowed.
d) d) The re-freshening action shall take place at least 10 minutes prior to the pad assembly.
e) e) A suitable solvent has been found to be lead-free gasoline (normal heptane’s), with a
distillation range from 40 °C to 141 °C and a maximum recovery of 97 %, available from most solvent
suppliers.
5.7 Rubber cutter
a) a) The rubber cutter shall be able to cut rubber with a thickness of 7 mm with acceptable
precision to achieve correct rubber sheath dimensions.
b) b) A big paper cutter or clicker dies with exact target dimensions are to be used.
5.8 Consumable
5.8.1 Rubber compound
a) a) The rubber compound can be provided in sheath form, 7 mm thick on a non-hygroscopic
backing, such as a plasticizer free plastic material, or may be provided un-milled in a form requiring
milling immediately prior to use.
b) b) The rubber compound shall be provided together with information on storage conditions and
shelf - life. If no specific requirements are specified by agreement between relevant parties, the storage
conditions and shelf - life shall comply with the following requirements:
1) 1) The rubber compound shall be stored in the laboratory environment with a temperature of
(23 ± 5) °C and a humidity of (40- to 55) % RH. I
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