ASTM D1578-93

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Designation: D 1578 – 93
Standard Test Method for
Breaking Strength of Yarn in Skein Form
This standard is issued under the fixed designation D 1578; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This test method covers the determination of the break- 2.1 ASTM Standards:
ing strength of yarn in skein form. The observed breaking D 76 Specification for Tensile Testing Machines for Tex-
strength is expressed in units of force, and equations are tiles
provided to convert breaking strength to skein breaking tenac- D 123 Terminology Relating to Textiles
ity and to skein break factor. D 1776 Practice for Conditioning Textiles for Testing
D 1907 Test Method for Yarn Number by the Skein
NOTE 1—For the determination of the breaking strength and elongation
Method
of yarn by the single strand method, refer to Test Method D 2256.
D 2256 Test Method for Tensile Properties of Yarns by the
1.2 This test method is applicable to spun yarns, either
Single-Strand Method
single or plied, composed of any fiber or blend of fibers, but is
D 2258 Practice for Sampling Yarn for Testing
not suitable for yarns which stretch more than 5 % when the
D 2904 Practice for Interlaboratory Testing of a Textile Test
tension is increased from 2.5 to 7.5 mN/tex or 0.03 to 0.08
Method that Produces Normally Distributed Data
gf/denier.
1.3 This test method provides three options based on the
3. Terminology
perimeter of the reel, the number of wraps in the skein, and the
3.1 Definitions:
machine speed or time-to-break.
3.1.1 breaking force, n—the maximum force applied to a
1.3.1 Option 1—Eighty, forty, or twenty turns on a 1.50-m
material in a tensile test carried to rupture.
or 1.5-yd reel, broken at 300 mm/min or 12 in./min.
3.1.1.1 Discussion—Force is commonly expressed as mil-
1.3.2 Option 2—Fifty turns on a 1.00-m or 1-yd reel, broken
linewtons (mN), newtons (N), grams-force (gf), or pounds-
at 300 mm/min or 12 in./min.
force (lbf).
1.3.3 Option 3—Fifty turns on a 1-m reel, broken in 20 s.
3.1.2 force, n—a physical influence exerted by one body on
another which produces acceleration of bodies that are free to
NOTE 2—Option 1 is in general use in the United States, Option 2 is
used for woolen yarns, and Option 3 has been proposed in the Interna-
move and deformation of bodies that are not free to move.
tional Standards Organization (ISO) for international use.
(Compare strength).
NOTE 3—Metric reels are available with 1 and 1.125-m circumferences.
3.1.3 skein break factor, n—the comparative breaking
Data from the two reels will be about 1 % different (see 5.6). ISO uses a
strength of a skein of yarn adjusted for the linear density of the
1-m circumference reel.
yarn expressed in an indirect system; the product of the
1.4 This test method is frequently combined with the
breaking strength of the skein and the yarn number expressed
determination of linear density carried out on the same skeins.
in an indirect system. (Syn. count-strength product)
Special precautions for reeling such skeins are noted.
3.1.3.1 Discussion—A statement of the break factor of the
1.5 Where appropriate, this test method states all require-
skein must indicate the number of wraps in the skein if this is
ments in SI units. The traditional units are inch-pound and are
not otherwise apparent; without information on the number of
exact values.
wraps, a statement of the break factor is meaningless. Break
1.6 This standard does not purport to address all of the
factor is frequently given other designations such as lea count
safety problems, if any, associated with its use. It is the
constant, lea product, and breaking ratio.
responsibility of the user of this standard to establish appro-
3.1.4 skein, n—a continuous strand of yarn in the form of a
priate safety and health practices and determine the applica-
flexible coil having a large circumference in proportion to its
bility of regulatory limitations prior to use.
thickness.
3.1.5 skein breaking tenacity, n—the skein breaking
strength divided by the product of the yarn number in a direct
numbering system and the number of strands placed under
This test method is under the jurisdiction of ASTM Committee D-13 on Textiles
tension.
and is the direct responsibility of Subcommittee D13.58 on Yarn Test Methods,
General.
Current edition approved July 15, 1993. Published September 1993. Originally
published as D 1578 – 58 T. Last previous edition D 1578– 88. Annual Book of ASTM Standards, Vol 07.01.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 1578
3.1.5.1 Discussion—Observed breaking strength can be determine yarn number for any purpose, the skeins must be
converted to breaking tenacity by dividing the breaking reeled under controlled tension on a reel meeting the require-
strength by the product of the yarn number measured in a direct ments given in Test Method D 1907.
numbering system and the number of strands placed under 5.5 For some purposes it may be advisable to convert the
tension (twice the number of wraps in the skein (see Eq 7)).
skein breaking strength observed for yarn of one number to the
3.1.6 skein strength, n—the force required to rupture a skein estimated skein breaking strength of a different yarn number.
of yarn, expressed in units of force, as breaking strength.
Factors for making such a conversion for cotton yarns are
3.1.7 strength, n—the property of a material that resists given in 11.2. No corresponding factors have been developed
deformation induced by external forces. (Compareforce).
for yarns spun from other fibers.
3.1.8 For definitions of other textile terms used in this test
5.6 The results obtained from different options are not fully
method, refer to Terminology D 123.
comparable because the breaking force per wrap increases
slightly as the perimeter of the skein is reduced. The skein
4. Summary of Test Method
breaking tenacity observed for 1-m skeins may be as much as
4.1 A skein of yarn, prepared by winding the prescribed
4 % higher, and from 1-yd skeins 5 % higher, than that
number of turns on a reel, is broken on a tensile testing
observed for 1.5-yd skeins. These relationships may vary with
machine.
the type of yarn or with yarn unevenness and should not be
used as conversion factors. With a reasonable number of
NOTE 4—If the yarn number is also required for the determination of
skein breaking tenacity or break factor, the broken skein may be weighed
specimens, this method provides a useful index that combines
and the yarn number calculated as directed in Test Method D 1907.
the effects of unevenness and single strand strength.
5.7 This method is rarely, if ever, used for filament yarns
5. Significance and Use
because their uniformity makes it possible to obtain reliable
5.1 Test Method D 1578 for testing any spun yarn for
results economically by the single-strand method.
breaking strength is considered satisfactory for acceptance
testing of commercial shipments since the method has been
6. Apparatus
used extensively in the trade.
6.1 Reel—A hand or motor-driven reel having a perimeter
5.1.1 In case of a dispute arising from differences in
of 1.50 m or 1.5 yd for Option 1, 1.0 m or 1 yd for Option 2
reported test results when using Test Method D 1578 for
(see Note 3), or 1 m for Option 3. The reel shall be fitted with
acceptance testing of commercial shipments, the purchaser and
a traversing mechanism that will minimize bunching the yarn
the supplier should conduct comparative tests to determine if
on the reel and with an indicator of the length wound. A
there is a statistical bias between their laboratories. Competent
warning bell or an automatic cutoff that will operate at a
statistical assistance is recommended for the investigation of
specified number of turns is advisable. It is also recommended
bias. As a minimum, the two parties should take a group of test
that the reel have a collapsible arm for relaxing the tension on
specimens which are as homogeneous as possible and which
the skeins to facilitate their removal from the reel. If yarn
are from a lot of material of the type in question. The test
number is to be determined from the same skeins, refer to Test
specimens should then be randomly assigned in equal numbers
Method D 1907 for additional reel specifications.
to each laboratory for testing. The average results from the two
6.2 Package Holders—Vertical spindles for bobbins or
laboratories should be compared using Student’s t-test for
cones if not provided as an integral part of the reel, shafts on
unpaired data and an acceptable probability level chosen by the
which tubes or flanged spools can turn freely.
two parties before testing is begun. If a bias is found, either its
6.3 Tensile Testing Machine—A constant-rate-of-traverse
cause must be found and corrected or the purchaser and the
(CRT type) or constant-rate-of-extension (CRE type) tensile
supplier must agree to interpret future test results in the light of
testing machine of suitable capacity as prescribed in Specifi-
the known bias.
cation D 76, capable of operating the moving clamp (spool) at
5.2 This test method is not suitable for yarns that stretch
a uniform speed of 300 6 10 mm/min or 12 6 0.5 in./min (for
more than 5 % when the force is increased from 2.5 to 7.5
Options 1 and 2) or capable of operating at a rate that will
mN/tex or 0.03 to 0.08 gf/denier, because (a) they require
break the skein broken in an average time of 20 6 3 s from the
special precautions as to tension in reeling, and (b) users of
start of application of tension to the skein (for Option 3). The
such yarns are more interested in their elastic behavior at low
machine shall be equipped with spools not less than 25 mm or
forces than in their ultimate breaking strength.
1 in. nor more than 30 mm or 1.25 in. in both diameter and
5.3 For Option 1, it is advisable to use a tensile testing
length, and supported with at least one spool free to turn on its
machine of the proper capacity to break skeins with 80 turns.
axis. The distance between the spools shall be sufficient to
If it is necessary to break skeins having only 40 or 20 turns,
permit placing the skeins on the spools in a wide, flat band.
convert the observed results to an 80-turn basis by multiplying
6.4 Skein Holder or Rack, having parallel pegs or bars
by factors of 2 or 4, respectively. (The available literature does
placed a sufficient distance apart to hold the skeins extended to
not show that any significant error is introduced by the use of
nearly their full length without either stretching, kinking, or
these factors.)
entangling the yarn.
5.4 The circumference of the skeins used to determine the
breaking load is not critical, and as a consequence, close
7. Sampling
control of the tension at which the skeins are wound is not
necessary. If, however, the same skeins are to be used to 7.1 Lot Sample—Take a lot sample as directed in an
D 1578
applicable specification, or as agreed upon between the pur- umbrella reel or swift and reel at a speed of 20 to 30 rpm.
chaser and the supplier. In the absence of an applicable 9.2 Reeling—Draw each end of yarn through a separate
specification or agreement, take a lot sample as directed in guide and attach the yarn to the reel. Turn the reel at a uniform
Practice D 2258. speed and maintain sufficient tension to lay the yarn smoothly
on the reel. When the required number of turns have been
NOTE 5—An adequate specification or other agreement between the
reeled, tie the ends of the yarn together loosely but securely
purchaser and the supplier requires taking into account variability between
with a nonslipping knot. For easier separation of skeins on the
shipping units, between packages or ends within a shipping unit, and
between specimens from a single package so as to provide a sampling plan rack, a loose loop may be made about the skein cross section,
with a meaningful producer’s risk, consumer’s risk, acceptable quality
and the yarns once again knotted. If skein breaking tenacity or
level, and limited quality level.
skein break factor is to be calculated, the method of reeling
must comply with the additional requirements in Test Method
7.2 Laboratory Sample—As a laboratory sample for accep-
D 1907.
tance testing, take a total of ten packages for yarn spun on the
9.2.1 For Option 1, reel 80 turns on a 1.50-m (1.5-yd) reel.
cotton or worsted systems and a total of 20 packages for yarns
If the breaking strength of such a skein is greater than the
spun on the woolen system. Select the packages randomly from
capacity of the available testing machine, try 40 or 20 turns.
all the packages in the lot sampling units.
9.2.2 For Option 2, reel 50 turns on a 1-m or a 1-yd reel.
7.3 Number of Specimens—Test one skein from each pack-
9.2.3 For Option 3, reel 50 turns on a 1-m (1.09–yd) reel.
age in the laboratory sample.
Include extra skeins for adjustment of the tester for time to
8. Conditioning
break.
8.1 Preconditioning—Yarns for testing should be wound 9.3 Conditioning—Transfer the skeins to the rack carefully
into skeins for preconditioning and conditioning (see Section with as little disturbance of the yarn as possible. Keep the yarns
9). Reel one or more extra skeins for use in determining when parallel and the skein flat, with no bunching or twisting. Do not
moisture equilibrium has been reached (see 8.2.1). stretch or jerk the yarn and do not allow it to kink. If more than
8.1.1 Precondition the skeins at a temperature no higher one skein is to be stored on each pair of pegs, the skeins may
than 50°C or 120°F in an atmosphere having a relative be transferred one at a time to the rack, with rings or washers
humidity between 5 and 25 %. Skeins will usually reach placed between them for easier separation. Precondition (if not
approximate moisture equilibrium in 4 h especially in moving done before reeling) and condition as prescribed in Section 8.
air. Crowding skeins too close together on the rack, or anything Do not remove the skeins from the rack until time of test.
that obstructs the circulation of air, may lengthen the time
10. Procedure
appreciably.
10.1 Perform all tests in the standard atmosphere for testing
8.2 Conditioning—Condition the skeins in the standard
textiles, which is 21 6 1°C or 70 6 2°F and 65 6 2 % relative
atmosphere for testing textiles, which is 21 6 1°C or 70 6 2°F
humidity.
and 65 6 2% relative humidity, until moisture equil
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