ASTM D1423/D1423M-16(2022)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D1423/D1423M − 16 (Reapproved 2022)
Standard Test Method for
Twist in Yarns by Direct-Counting
This standard is issued under the fixed designation D1423/D1423M; 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 (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope 1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 This test method covers the determination of the amount
responsibility of the user of this standard to establish appro-
and direction of twist at the completion of any stage of twisting
priate safety, health, and environmental practices and deter-
insingle(spunorfilament),plied,cabled,ornovelty(exclusive
mine the applicability of regulatory limitations prior to use.
of long-term repeat patterns) yarns. The procedures are de-
1.6 This international standard was developed in accor-
signed primarily for yarns in packages, but, with special
dance with internationally recognized principles on standard-
precautions, they are applicable to yarns taken from fabrics.
ization established in the Decision on Principles for the
The procedure for spun yarn in 9.2 is also applicable to
Development of International Standards, Guides and Recom-
rovings.
mendations issued by the World Trade Organization Technical
1.2 For plied yarns, this test method covers the determina-
Barriers to Trade (TBT) Committee.
tion of the twist of the plied yarns and the twist of the single
yarnbeforeplying.Forcabledyarns,thetestmethodcoversthe
2. Referenced Documents
determination of the cable or hawser twist; the twist of the
2.1 ASTM Standards:
plied yarn after plying, but prior to the last twisting operation;
D123 Terminology Relating to Textiles
and the twist of the single yarn before plying. Procedures are
D1059 Test Method for Yarn Number Based on Short-
also included for the determination of the twists of the single
Length Specimens
and plied yarn components as they lie in the final structure.
D1422 Test Method for Twist in Single Spun Yarns by the
Also, directions are included for the determination of twist in
Untwist-Retwist Method
plied yarn made with direct cabling technology.
D1776 Practice for Conditioning and Testing Textiles
1.3 This test method is not intended for yarns that extend
D1907 Test Method for Linear Density of Yarn (Yarn Num-
more than 5.0 % when tension is increased from 2.5 to 7.5 ber) by the Skein Method
mN/tex [0.25 to 0.75 gf/tex]. Following the procedures of this
D3888 Terminology for Yarn Spinning Systems
test method for such yarns would be independent of the bias D4849 Terminology Related to Yarns and Fibers
and precision determined for this test method. The report from
3. Terminology
such testing should include the tension used for this testing.
3.1 Refer to Terminology D4849 for definitions of the
1.4 Units—The values stated in either SI units or inch-
following terms used in this standard: direction of twist, single
pound units are to be regarded separately as standard. The
yarn, spun yarn, twist, twist factor, twist multiplier, and yarn.
values stated in each system are not necessarily exact equiva-
lents; therefore, to ensure conformance with the standard, each
3.2 Refer toTerminology D123 andTerminology D3888 for
system shall be used independently of the other, and values
definitions of other terms used in this standard.
from the two systems shall not be combined.
4. Summary of Test Method
NOTE 1—For a more rapid but less accurate method of determining
twist in single spun yarns, refer to Test Method D1422.
4.1 A specified length of specimen is mounted in a twist
NOTE 2—This test method has been evaluated for use in determining
device. One end is rotated until all the elements are free of
twist in open end yarns and is not recommended.
twist. The number of turns is counted and the turns per unit
length are calculated.
This test method is under the jurisdiction ofASTM Committee D13 on Textiles
and is the direct responsibility of Subcommittee D13.58 on Yarns and Fibers. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Feb. 1, 2022. Published March 2022. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1956. Last previous edition approved in 2016 as D1423–02(2016). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D1423_D1423M-16R22. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D1423/D1423M − 16 (2022)
4.2 The amount of twist in the component elements of a singles twist. For a more precise determination, the test
plied or cabled yarn is determined by either of two options. procedure must be modified. There are thus two different
proceduresforpreparingspecimensofthecomponentelements
4.2.1 In the procedure for determining original twist, one
end of the yarn is fixed while the other end is rotated until the ofapliedorcabledyarnfortwistdetermination.Theprocedure
for the original twist measures the twist in a component of a
structural components are parallel. Any one or all of these
components may then be used as test specimens. complex strand after the components have been untwisted.The
procedure for final twist measures the twist in a component as
4.2.2 In the procedure for determining final twist in
it lies in the complex strand. Although the original twist
components, both ends of one component of the yarn are held
procedure is most often used, selection of a particular proce-
fixed while all the other components are removed and dis-
dure will depend on the type of information needed.
carded. The twist is then determined in the remaining compo-
nent.
NOTE 3—The difference in twist between unwinding from the side and
over-end is 1/πd, where d is the diameter of the package. Thus, for a 25
mm [1-in.] diameter package, the difference would be about 13 tpm or
5. Significance and Use
about ⁄3 tpi.
5.1 Test Method D1423 for testing twist in yarns by
5.5 When a yarn is taken from a more complex yarn
direct-counting is considered satisfactory for acceptance test-
structure or from a fabric, the resultant twist should be
ing of commercial shipments because current estimates of
consideredonlyanapproximationoftheoriginalvaluebecause
between-laboratory precision are acceptable and the method
of alterations that may have occurred as a result of the effects
has been used extensively in the trade for acceptance testing.
ofunwinding,handling,andmechanicalstrainsmetinprocess-
5.1.1 If there are differences of practical significance be-
ing.
tween reported test results for two laboratories (or more),
5.6 The optimum amount of twist depends upon the use for
comparative tests should be performed to determine if there is
whichtheyarnisintended.Theamountoftwistaffectsboththe
a statistical bias between them, using competent statistical
strength and elongation properties of the yarn with increased
assistance. As a minimum use the samples for such compara-
twist being associated with increased elongation. The relation-
tive tests as homogeneous as possible, drawn from the same lot
ship between twist and strength is more complex.
of material that resulted in the disparate test results and
5.6.1 In filament yarns, some twist up to 280 tpm [7 tpi] or
randomly in equal numbers to each laboratory. The test results
a suitable sizing is required to facilitate textile operations. A
from the laboratories involved should be compared using a
small increase in twist results in a slight increase in strength,
statistical test for unpaired data, at a probability level chosen
but a further increase results in a loss in strength. However,
prior to the testing series. If a bias is found, either its cause
higher twist in such yarns may be used to subdue luster or
must be found and corrected, or future test results for that
increase elongation, or to secure other special effects, as in
material must be adjusted in consideration of the known bias.
crepe fabrics.
5.2 The determination of twist in a straight section of a yarn
5.6.2 In conventional ring spun yarns a certain minimum
is not the simple straightforward operation it appears to be, for
amount of twist is necessary to bind or hold the individual
the test results may be greatly influenced by variations in test
fibers together to produce a useful yarn. A limited increase in
procedures and techniques. In all manipulations, extreme care
twist will result in an increase in strength until the critical twist
is necessary to prevent specimen rotation altering the twist
level for the particular yarn involved has been reached, but
level before testing begins.
further increase in twist results in a loss in strength.
5.3 The twist in a yarn before it is packaged may be
5.7 The same amount of twist in yarns of different sizes
different from that of the yarn after it has been withdrawn from
(diameter) will produce yarns with different degrees of
the package because of changes in tension and the effect of the
compactness, twist character, and twist angles. The twist
method of withdrawal. If the yarn is withdrawn over-end, a
multiplier or twist factor is approximately proportional to the
slight increase or decrease in twist will take place, depending
tangent of the angle that the surface fibers make with the axis
upon the direction of the twist in the yarn, the direction of
of the yarn. Therefore, the greater the angle, the greater the
winding on the package, and the length of the wrap on the
twist multiplier. A constant twist multiplier indicates compa-
package.
rable compactness and degree of liveliness in yarns of different
5.4 When a yarn is incorporated into or removed from a sizes and conversely a difference in twist multiplier indicates a
morecomplexstructure,alterationsmayoccurasaresultofthe
difference in compactness in yarns of the same size. Yarns
plying, untwisting, or raveling operation. For example, when intended for different uses are frequently made with different
determining the twist in plied yarn by the procedure for
twist multipliers, for example, warp yarns and filling yarns.
determining original twist, as the plied yarn is untwisted, a
5.8 Different cabling processes will influence the calcula-
comparable amount of twist is reinserted in, or removed from,
tion of twist from single component twist measurement. The
thesingle-yarncomponents.Asaconsequence,thesingleyarns
length of cabled yarn before untwisting is used for the
have approximately the original twist prior to the plying
calculation of twist for single components using direct cabling
operation but not the twist they have when they are functioning
as components of the plied yarn. The latter or final twist may
be estimated by adding the ply twist to (or subtracting it from)
Woods, H. J., “The Kinematics ofTwist, I,The Definition ofTwist,”Journalof
the single-yarn twist depending on the directions of the ply and Textile Science, Vol 4, 1931, pp 33–36.
D1423/D1423M − 16 (2022)
technology. In case of 2 or more step twist technology the 7.4.1 Take an approximate equal number of specimens from
length of the cabled yarn after untwisting is used for calcula- each package or unit of the laboratory sample. Take the
tion of the twist level in the single yarn components. specimens from each package in a random manner to minimize
the effect of cyclic variations introduced during the manufac-
5.9 Twist multiplier and twist factor are a measure of the
turing processes. When preparing specimens, conditioning
“twist hardness” of spun yarn because they are approximately
them or inserting them in the tester, take care to avoid any
proportional to the tangent of the angle between fibers on the
change in twist.
outer yarn surface and the axis of the spun yarn; the larger this
7.4.2 For packaged yarns, remove and discard the first 25 m
angle,theharderthetwist.Furthermore,thisangleisafunction
[25 yd] of yarn. Using a minimum of tension, take specimens
of both the twist content (turns per unit length) and the number
at random intervals greater than1m[1yd] along the yarn.
of fibers per yarn cross section (yarn number). Hence, twist
Withdraw the yarn from the package in the direction of normal
contentalonecannotprovideameasureofthetwisthardnessof
use, either from the side or over-end, if known. If the direction
a yarn.
is not known withdraw the yarn from the side (Note 3). When
6. Apparatus more than five specimens are taken from an individual
package, take groups of five or less at intervals of several
6.1 TwistTester,consistingofapairofclamps,oneofwhich
yards. Do not cut the specimen free from the package or from
is rotatable in either direction and positively connected to a
the yarn to be discarded until after the yarn is secured in the
revolution counter. The tester may be hand- or power-driven.
clamps of the twist tester. When possible, take the specimen
The position of one clamp (or both clamps) shall be adjustable
from near the center of the traverse and not at the traverse
to accommodate specimens of the lengths specified in 9.2 and
reversals.
9.3 and to permit measuring the change in length during
7.4.3 For woven fabric, take warp specimens from separate
untwisting. Means shall be provided for applying the specified
ends, since each represents a separate package. Because the
tensions to the specimen and for determining the specimen
fabric may have been woven on any of a variety of looms
length with an accuracy of 60.5 mm [0.02 in.]. The movable
which are random quilling, sequential quilling or shuttleless,
butnonrotatableclampshallbecapableofbeingtraversedwith
take filling specimens at random through the whole laboratory
substantially no friction to permit determining the untwisted
sample to obtain as representative data as possible. A strip
length of the specimen under the specified tension. The
about2m[2yd] long is recommended as a source for filling
counting device shall be resettable to zero count and shall
yarn specimens.
indicate the total number of turns to the nearest 0.1 turn.
7.4.4 For weft-knit fabric, known to be multi-feed, take
6.2 Dissecting Needle or Stylus.
specimensfromsuccessivecoursesinoneportionoflaboratory
6.3 Gaug
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