DRAFT INTERNATIONAL STANDARD

ISO/DIS 9073-18

ISO/TC 38 Secretariat: SAC

Voting begins on: Voting terminates on:
2023-01-27 2023-04-21

Nonwovens — Test methods —

Part 18:
Determination of breaking strength and elongation using
the grab tensile test

ICS: 59.080.30

This document is circulated as received from the committee secretariat.

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ISO/DIS 9073-18:2023(E)
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ISO/DIS 9073-18:2023(E)

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Contents Page

Foreword......................................................................................................................................................................................................................................... iv
1 Scope.................................................................................................................................................................................................................................. 1
2 Normative references...................................................................................................................................................................................... 1
3 Terms and definitions..................................................................................................................................................................................... 1
4 Principle......................................................................................................................................................................................................................... 3
5 Reagents and materials................................................................................................................................................................................. 3
6 Apparatus..................................................................................................................................................................................................................... 3
6.1 tensile testing machine,................................................................................................................................................................... 3
6.2 clamps and jaw faces,......................................................................................................................................................................... 4
6.3 container,...................................................................................................................................................................................................... 4
7 Sampling........................................................................................................................................................................................................................ 4
7.1 Lot sampling.............................................................................................................................................................................................. 4
7.2 Laboratory sample............................................................................................................................................................................... 5
7.3 Test specimens........................................................................................................................................................................................ 5
8 Conditioning.............................................................................................................................................................................................................. 5
9 Preparation of specimens........................................................................................................................................................................... 6
9.1 General............................................................................................................................................................................................................ 6
9.2 Grab test........................................................................................................................................................................................................ 6
9.3 Marking on the test specimen.................................................................................................................................................... 6
9.4 Wet test specimens.............................................................................................................................................................................. 6
10 Preparation, calibration, and verification of apparatus............................................................................................ 6
10.1 Tensile testing machine................................................................................................................................................................... 6
10.2 Clamping system.................................................................................................................................................................................... 7
10.3 Verification of the total operating system of the apparatus........................................................................... 7
11 Procedure..................................................................................................................................................................................................................... 7
12 Calculation................................................................................................................................................................................................................... 8
12.1 Calculation of breaking force...................................................................................................................................................... 8
12.2 Measurement of apparent elongation................................................................................................................................. 8
12.3 For each testing situation.............................................................................................................................................................. 8
13 Expression of results........................................................................................................................................................................................ 9
14 Precision and bias............................................................................................................................................................................................... 9
14.1 Precision........................................................................................................................................................................................................ 9
14.2 Bias..................................................................................................................................................................................................................... 9
15 Test report................................................................................................................................................................................................................... 9
Annex A (informative) Possible causes of low precision.............................................................................................................. 11
Bibliography..............................................................................................................................................................................................................................12

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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 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 38 [Textiles] Working Group WG9
[Nonwovens].
This second edition cancels and replaces the first edition (ISO 9073-18:2007) which has been technically
revised.
The main changes compared to the previous edition are as follows:
— Textual update;
— Title review and update.
— Annex B and Table B.1 exhaustively list the modifications made.
A list of all parts in the ISO-9073 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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DRAFT INTERNATIONAL STANDARD ISO/DIS 9073-18:2022(E)

Nonwovens — Test methods —

Part 18:
Determination of breaking strength and elongation using
the grab tensile test
SAFETY WARNING — This standard does not claim to address all of the safety concerns, if any,
associated with its use. It is the responsibility of the user of this standard to establish appropriate
safety and health practices and determine the applicability of regulatory limitations prior to
use. It is expected that the person performing this test has been fully trained in all aspects of
this procedure.

1 Scope
This document specifies a test method for the determination of the breaking force using a grab method
in conditioned or wet state.
This test method is not recommended for materials which have a high percentage of stretch. This
document is applicable for testing nonwoven materials in either a dry or wet condition. Comparing test
results from tensile testing machines operating on different principles is not recommended.

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 139, Textiles — Standard atmospheres for conditioning and testing
ISO 186, Paper and board — Sampling to determine average quality
ISO 2859-1, Sampling procedures for inspection by attributes — Part 1: Sampling schemes indexed by
acceptance quality limit (AQL) for lot-by-lot inspection
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 3951-1, Sampling procedures for inspection by variables — Part 1: Specification for single sampling
plans indexed by acceptance quality limit (AQL) for lot-by-lot inspection for a single quality characteristic
and a single AQL

3 Terms and definitions

For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://​w ww​.iso​.org/​obp
— IEC Electropedia: available at https://​w ww​.electropedia​.org/​

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3.1
breaking force
maximum force applied to a material carried to rupture
Note  1  to  entry:  Materials that are brittle usually rupture at the maximum force. Materials that are ductile
usually experience a maximum force before rupturing.

3.2
maximum force
maximum force appearing during a test specimen carried to rupture in a tensile test under the specified
conditions
3.3
constant-rate-of-extension (CRE) tensile testing machine
tensile-testing machine provided with one clamp which is stationary and another clamp which moves
with constant speed throughout the test, the entire testing system being virtually free from deflection
3.4
constant-rate-of-load (CRL) tensile testing machine
testing machine in which the rate of increase of the load being applied to the specimen is uniform with
time after the first 3 s
3.5
grab test
tensile test in which only the centre part of the test specimen is gripped in the jaws of the testing
machine
3.6
elongation
deformation in the direction of load caused by a tensile force, generally expressed as a ratio of the
length of the stretched material as a percentage to the length of the unstretched material
Note 1 to entry: Elongation may be determined by the degree of stretch under a specific load or the point where
the stretched material breaks.

3.7
extension
change in length of a material due to stretching (compare elongation)
3.8
grab strength test
measure of the “effective strength” of a fabric, i.e. the strength of fibres in a specific width together
with the additional strength contributed by adjacent fibres
Note 1 to entry: Typically, grab strength is determined on a 200 mm wide strip of fabric, with the tensile load
applied at the midpoint of the fabric width through 25 mm wide jaw faces that are used to clamp the fabric.

3.9
sample
product or a portion of a product taken from a production lot for testing purposes, identifiable and
traceable back to the origin
3.10
test specimen
specific portion of the identified sample upon which a test is performed. Many specimens may be tested
from the same sample, using different locations
3.11
tensile strength
resistance of a material to breaking under tension Note to entry 4: Tensile strength is preferably
expressed in Newton

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3.12
gauge length
distance between the two effective clamping points of a testing device
Note 1 to entry: The effective clamping points (or lines) of jaws can be checked by clamping a test specimen with
carbon copy paper to produce a gripping pattern on the test specimen and/or the jaw faces.

3.13
lot size
a lot should be established based on a logical break in the process or as prescribed by a regulation or
traceability requirements

4 Principle
A test specimen, gripped in its centre part by jaws of specified dimensions, is extended at constant rate
until it ruptures. The maximum force is recorded. Values for the breaking force and the elongation of
the test specimen are obtained from test instrument; scales, dials, autographic recording charts, or a
computer interfaced.

5 Reagents and materials

5.1 grade 3 water, according to ISO 3696, for wet testing

5.2 non-ionic wetting agent, for wet testing

5.3 blotting paper, two sheets required for the test on wet test specimens

6 Apparatus

6.1 tensile testing machine,

could be any one of the two types, (CRE or CRL). Both two types have the capabilities with respect
to force indication, working range, capacity, and elongation indicator The constant-rate-of-extension
tensile testing machine is preferred for this method.
NOTE 1 Comparison of results from tensile testing machines operating on different principles is not
recommended, but when different types of machines are used for comparison testing, constant time-to-break at
(20 ± 3) s is the established way of producing data.

NOTE 2 For metrological confirmation system of the tensile-testing machine shall be referred to ISO 10012
and for accuracy of the apparatus shall be referred to ISO 7500-1. The constant-rate-of-extension (CRE) machine
shall have the general characteristics given in 6.1.1 to 6.1.4.

6.1.1 The tensile-testing machine shall be provided with means for indicating or recording the force
applied to the test specimen in stretching it to rupture. Under conditions of use, the accuracy of the
apparatus shall be class 1 of ISO 7500-1. The error of the indicated or recorded maximum force at any
point in the range in which the machine is used shall not exceed ±1 %.

6.1.2 If a class 2 tensile-testing machine according to ISO 7500-1 is to be used, this shall be stated in
the test report.

6.1.3 If recording of force is obtained by means of data acquisition boards and software, the frequency
of data collection shall be at least eight per second.

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6.1.4 The machine shall be capable of a constant rate of extension of 300 mm/min, with an accuracy
of ±10 %.

6.2 clamps and jaw faces,

with the central point of the two jaws in the line of applied force, the front edges shall be at right angles
to the line of applied force and their clamping faces shall be in the same plane. The jaws shall be capable
of holding the test specimen without allowing it to slip and designed so that they do not cut or otherwise
weaken the test specimen.
Each jaw face shall be smooth, flat, and metallic, or any other agreed upon gripping surface except that
when, even with packing, the test specimen cannot be held satisfactorily with flat-faced jaws, engraved
or corrugated jaws can be used to prevent slippage. Other auxiliary materials for use with either smooth
or corrugated jaws to improve specimen gripping include paper, leather, plastics, or rubber. The faces
shall be parallel and have matching centres with respect to one another in the same clamp and to the
corresponding jaw face of the other clamp.
For grab tests, each clamp shall have a front (or top) jaw face measuring (25 ± 0,5 mm) mm perpendicular
to the direction of the application of the force, and not less than 25 mm nor more than 50 mm parallel to
the direction of the application of force. The back, or bottom, jaw face of each clamp shall be at least as
large as its mate. Use of a larger face for the second jaw reduces the problem of front and back jaw face
misalignment. The other jaw of each clamp shall be at least as wide as the one to which it is attached
and should preferably be 50 mm wide.

6.3 container,
in which test specimens can be immersed in water preparatory to wet testing

7 Sampling

7.1 Lot sampling

Carry out sampling in accordance with ISO 186. Ensuring that the areas from which samples are taken,
have no visible flaws and are not creased.
If provided in the customer specification, take random sample as directed. If no requirements are
provided, ISO 2859-1 (Sampling procedures for inspection by attributes) or ISO 3951-1 (Sampling
procedures for inspection by variables) can be used. In and of themselves, these are not valid sampling
plans by default. An agreement between the purchaser and supplier requires taking into account
process stability, producer’s risk, consumer’s risk, acceptable quality level and also the cost needs to be
established.
In general, if the test characteristic can be considered normally distributed, the sampling procedures
for inspection by variables will require fewer samples. However, small samples may not reflect that
normal distribution and the estimated percent defective can therefore be over or underestimated. In
this case, as well as for attribute data, the sampling procedures for inspection by attributes should be
used.
In the absence of any sampling size requirement, the following tables can be used. Switching rules are
required to maintain the AQL protection.
Table 1 below illustrates the inspection by attributes, while Table 2 illustrates the inspection by
variables.

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Table 1 — Attributes (1.0 AQL, General Inspection Level II)

Number of units in the lot inclusive Number of units that comprise the lot sample
1 to 150 13
151 to 280 32
281 to 500 50
501 to 1200 80

Table 2 — Variables (“s” method, General Inspection Level II)

Number of units in the lot inclusive Number of units that comprise the lot sample
1 to 15 3
16 to 25 4
26 to 50 6
51 to 90 9
91 to 150 13
151 to 280 18
281 to 500 25
501 to 1200 35

NOTE An adequate specification or other agreement between the purchaser and supplier requires taking
into account the variability between rolls of nonwoven fabric and between specimens from a swatch from a roll
of material to provide a sampling plan with meaningful producer’s risk, consumer’s risk, acceptable quality level,
and limiting quality level.

7.2 Laboratory sample

From each roll or portion of material taken from the lot sample, cut at least one laboratory sample the
full width of the fabric and 1m in the machine direction.
NOTE Results obtained on small hand samples can only be considered as representative of that sample
and cannot be assumed to be representative of the material portion from which the hand sample or swatch was
taken.

7.3 Test specimens

Take the test specimens from areas of the sample that are free of folds, wrinkles and any distortions
that would make these specimens abnormal from the rest of the test material.

8 Conditioning
Bring samples to moisture equilibrium in the standard atmosphere for testing nonwovens as specified
in ISO 139. Equilibrium is considered to have been reached when the increase in mass of the specimen
in successive weighing made at intervals of not less than 2 hours does not exceed 0,25 % of the mass of
the specimen. Preconditioning and conditioning are not required for tests in the wet condition.
NOTE While conditioning for a fixed time cannot be accepted in cases of dispute, it may be sufficient in
routine testing to expose the material to the standard atmosphere for testing textiles for a reasonable period
of time before the specimens are tested. It is recommended that samples be conditioned for at least 24 h in the
relaxed state.

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9 Preparation of specimens

9.1 General
From each laboratory sample, two sets of test specimens shall be cut, one set in the machine direction
and the other in the cross-machine direction. Cut specimens with their long dimensions parallel either
to the machine direction or to the cross direction. Prepare at least three of test specimens.
NOTE The length of the specimen depends on the type of clamps being used. The specimen should be long
enough to extend through the clamps and project at least 10 mm at each end.

When the maximum force of the wet fabric is required in addition to the maximum force when dry, test
specimens of the appropriate width and at least twice as long as the test specimens required for a dry
test shall be cut. Each end of each strip shall be numbered, and then each test specimen shall be cut
crosswise into two parts, one for determining the dry maximum force and the other for determining
the wet maximum force. This ensures that each pair of test specimens contains the same longitudinal
yarns. For fabrics where it is suspected or known from previous experience that excessive shrinkage
will occur when wet, the length of test specimens for the determination of wet maximum force shall be
greater than that of test specimens for dry maximum force tests.

9.2 Grab test

Cut each specimen (100 ± 2) mm wide and its length shall be long enough to secure the gauge length of
100 mm.

9.3 Marking on the test specimen

On each test specimen, a line shall be drawn at distance of 37 mm from one edge, parallel to machine or
cross-machine direction, running the full length of the test specimen.

9.4 Wet test specimens

For tests in the wet condition, immerse the test specimen for a period of 1 h in grade 3 water, in
accordance with ISO 3696 at a temperature of 20 °C ± 2 °C. An aqueous solution containing not more
than 1 g of a non-ionic wetting agent per litter can be used instead of water. A test of any test specimen
shall be completed within two minutes after its removal from the water.
NOTE 1 For tropical regions, the temperature according to ISO 139 can be applied.

10 Preparation, calibration, and verification of apparatus

10.1 Tensile testing machine

10.1.1 Prepare the machine according to the manufacturer’s instructions and using the conditions
given in clause 10.1.1 to 10.1.3 (see Annex A).

10.1.2 Set the distance between the clamps (Gage length) at (75 ± 1) mm.

10.1.3 Select the force range of the testing machine for the break to occur between 10 % and 90 % of
full-scale force. Calibrate or verify the testing machine for this range.

10.1.3 Set the testing machine for a loading rate of (300 ± 10) mm/min unless otherwise specified.

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10.2 Clamping system

Check the jaw face surfaces for flatness and parallelism.
NOTE Some sources of clamping irregularities are surface contact, metal surface, or jaw coating-cover
surface, condition, and pressure application.

10.3 Verification of the total operating system of the apparatus

a) Verify the total operating system (loading, extension, clamping, and data collecting) by testing
specimens of a standard material for breaking force and elongation and comparing that data with
historical data from that same standard material. This verification of the system is recommended
on daily basis before use, but at a minimum should be done on a weekly basis. In addition, the total
operating system should be verified whenever there are changes in the load cells or change in grips
(clamping system).
b) Select and prepare the standard material which has breaking force and elongation in the range of
interest.
c) Check for adequacy of clamping pressure by mounting a specimen and marking the inner jaw face-
to-material junctions. Break the specimen and watch for movement of either line away from the
junction to indicate slippage. If slippage occurs, adjust the air pressure of pneumatic clamps or be
prepared to tighten manual clamps more when testing. If pressures cannot be increased without
causing jaw breaks, other techniques for eliminating slippage, such as jaw cushioning or specimen
tabbing, will be necessary.
d) Test the standard material specimens as directed in clause 11.
e) Calculate the breaking force and elongation, the averages and the standard deviations as directed
in clause 12.
f) Compare the data with previous data. If the average is outside the tolerances established, recheck
the total system to locate the cause for the deviation.

11 Procedure

11.1 Mount the specimen in the top and bottom clamps (jaws), so the gauge length of the tensile-
testing machine to 75 mm, to within ±1 mm. Carefully mount the specimen, so that all the slack in the
material is removed, but care should be taken so that pretension is not applied to the specimen.

11.2 Set the rate of extension of the tensile-testing machine to 300 mm/min.
NOTE Placing of the specimen into the upper and lower jaws of the tensile machine can be a large source
of error in performing this method. The elongation measurement is taken from the point where the force curve
leaves the zero line. Mounting the specimens carefully and methodically into the jaws can reduce some of the
technician error.

11.3 Clamp a test specimen centrally so that its longitudinal centre line passes through the centre
point of the front edges of the jaws and becomes perpendicular to the edges of the jaws to have the line
drawn on the test specimen coincide with one edge of the jaws.

After closing the upper jaw, avoid pretension when adjusting the specimen along the guideline in the
lower jaw so that the fabric hangs under its own weight when the lower clamp is closed.

11.4 Mark across the test specimen at the front inner edge of each jaw to check for specimen slippage.
When slippage occurs, the mark will move away from the jaw edge and the results of this test specimen
shall be discarded.

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11.5 Engage the device for recording the maximum force. Put the movable clamp in motion and extend
the test specimen to the point of rupture. Record the maximum force in newtons. Perform the test at
least on five test specimens of each fabric direction.

11.6 Perform the test according to 11.1 to 11.4 immediately after removal of a test specimen from the
liquid (see 9.4.2) and briefly placing it on blotting paper to remove excess water.

11.7 Disregard any test results where the test specimen slips asymmetrically or by greater than 2
mm along the clamping line. If a material manifests any slippage in the jaws or if more than 25 % of the
specimens break at a point within 5 mm of the edge of the jaw, one of the modifications listed below
may be tried. If any of these modifications are used, state the method of modification in the report.

a) The jaws may need to have rubber pads applied to each jaw surface.
b) The surface of the jaws may be serrated or notched to better hold the material.
c) Carefully check the surface of the jaws for any sharp edges that could be causing these breaks.
NOTE It is difficult to determine the precise reason for certain specimens to break near the edge of the jaws.
If such a break is caused by damage to the specimen by the jaws, then the results should be discarded. If, however,
the break is due merely to randomly distributed weak places, it is a legitimate result. In some cases, it may also
be caused by a concentration of stress in the area adjacent to the jaws because the jaws prevent the specimen
from contracting in width as the force is applied. In such cases, a break near the edge of the jaw is inevitable and
should be accepted as a characteristic of the particular material and the test method.

11.8 Record any break which occurs within 5 mm of the clamping line of jaws and report the result
as a jaw break. At the end of the five tests, examine the results obtained. If any of the jaw break results
falls above the lowest “normal” break result, then it can be included. If any of the jaw break results falls
below the lowest “normal” break result, then it shall be excluded, and further tests should be carried
out to obtain five “normal” breaks.

If all the results are jaw breaks, or if five “normal” breaks cannot be obtained, then the individual
results shall be reported without the coefficient of variation or confidence limits. Jaw break results
shall be indicated as such in the report, and the results discussed between the interested parties.

12 Calculation

12.1 Calculation of breaking force

For each laboratory sample and testing condition, calculate the average of the breaking force observed
for all acceptable test specimens, that is, the maximum force exerted on the test specimen as read
directly from the testing machine.

12.2 Measurement of apparent elongation

Unless some other force is specified, measure the apparent elongation of acceptable specimens at the
breaking force. Measure the increase in length from the start of the force-extension curve to a point
corresponding with the breaking force, or other specified force. Calculate the apparent elongation
as the percentage increase in length based on the gage length. Calculate the arithmetic mean of the
elongation at maximum force, and, if required, at rupture, for each direction tested and round it to the
nearest percentage point

12.3 For each testing situation

Calculate the average apparent elongation at the breaking force.

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13 Expression of results
Calculate the arithmetic mean of the maximum force and, if required, the arithmetic mean of the force
at rupture, in newtons, for each direction tested.

14 Precision and bias

14.1 Precision
The precision for this method is yet to be determined.

14.2 Bias
The bias for this method is yet to be determined.

15 Test report
The test report shall include the following information:
a) reference the test method used (i.e., ISO 9073-18: 2022);
b) complete identification of all samples tested;
c) name and address of testing institution;
d) make and model of testing equipment;
e) dimensions of the jaw faces used;
f) measuring ranges of the load cell used to perform the test;
g) individual test results;
h) arithmetic mean of the breaking force for specimens giving acceptable breaks specimens for each
testing condition (in CD and/ or MD), in Newton for each testing condition;
i) arithmetic mean of the elongation at break of acceptable specimens for each test condition if
requested;(in CD and/ or MD), in percent for each testing condition;
j) maximum force obtainable in the range used for testing;
k) types of modification used in the jaws if needed;
l) laboratory testing conditions;
m) number of specimens tested for each condition, including number of tests rejected and reasons for
this and its direction and note CD and/or MD if significant;
n) for computer processed data, identify the software used and the version;
o) deviation from the standard test procedure, if any;
p) when calculated, the standard deviation or the coefficient of variation. If required, calculate the
coefficient of variation to the nearest 0,1 % and the 95 % confidence limits of the relevant properties
tested, rounded to the same precision as the mean
q) state of test specimens (conditioned or wet) and whether or not samples were conditioned prior to
testing and, if so, for how long;
r) anything unusual noted during the testing;

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s) If not used SI units the values shall be reported in parallel.

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Annex A
(informative)

Possible causes of low precision

A.1 Equipment causes of error

A.1.1 Using different makes and models of tensile machines, i.e. the age and style of the machine can
make a difference

A.1.2 Using different measuring ranges of the load cells to test similar specimens

A.1.3 Using different software to calculate the test results

A.1.4 Using different laboratory conditions

A.1.5 Using different pre-conditioning periods for the test samples

A.2 Operation causes of error

A.2.1 Failure to recheck the zero after changing load cells, or other machine conditions

A.2.2 Failure to maintain proper and timely calibration on the machines and all load cells

A.2.3 Failure to properly train and maintain that training which is verified through periodic
proficiency testing

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Bibliography

[1] NWSP 001.0, Standard Terminology Relating to the Nonwoven Industry, EDANA’s and INDA’s
Standard Procedures
[2] ISO 10012, Measurement management systems — Requirements for measurement processes and
measuring equipment
[3] ISO 7500-1, Metallic materials — Calibration and verification of static uniaxial testing machines —
Part 1: Tension/compression testing machines — Calibration and verification of the force-measuring
system

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