ASTM D1422/D1422M-13(2020)
(Test Method)Standard Test Method for Twist in Single Spun Yarns by the Untwist-Retwist Method
Standard Test Method for Twist in Single Spun Yarns by the Untwist-Retwist Method
SIGNIFICANCE AND USE
5.1 This test method is used for acceptance testing in the trade for economic reasons even though it is less accurate than the direct method, Test Method D1423.
5.1.1 If there are differences or practical significance between reported test results for two laboratories (or more), comparative tests should be performed to determine if their is a statistical bias between them, using competent statistical assistance. As a minimum, the test samples should be used that are as homogeneous as possible, that are drawn from the material from which the disparate test results are obtained, and that are assigned randomly in equal numbers to each laboratory for testing. Other materials with established test values may be used for this purpose. The test results from the two laboratories should be compared using a statistical test for unpaired data, at a probability level chosen prior to the testing series. If a bias is found, either its cause must be found and corrected, or future test results must be adjusted in consideration of the known bias.
5.2 The “setting” of twist in some fibers causes excessive contraction when the yarn is retwisted in the reverse direction. Therefore, the number of turns required to bring the specimen back to its original length may be less than the number of turns removed in untwisting. This effect may be partially offset by the use of higher pretensioning loads; but this increases the danger of stretching the yarn. Little information is available on the correct tensions to use for yarns made from different fibers or with different amounts of twist.
5.3 In addition to being less tedious, this test method requires fewer specimens than the direct-counting method and the results may be sufficiently accurate for certain purposes. This test method can be useful in those cases where the main objective is to measure variations from an average value. Another possible application is where a large amount of twist testing is required on yarns of similar ty...
SCOPE
1.1 This test method2 describes the determination of twist in single spun yarns when only an approximation of the true twist is required.
Note 1: For a more accurate method see Test Method D1423.
1.2 This test method is applicable to spun single yarns in continuous lengths, and also to spun yarns raveled from fabrics, provided specimens at least 200 mm [8 in.] long can be obtained.
1.3 This test method has been found satisfactory for use in determining the approximate twist content in single ring spun yarns of all types and fiber contents, but not in open-end spun yarns.
1.4 This specification shows the values in both inch-pound units and SI units. The “inch-pound” units is the technically correct name for the customary units used in the United States. The “SI” units is the technically corrected name for the system of metric units known as the International System of Units. The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.
1.5 This standard does not purport 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.6 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.
General Information
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Standards Content (Sample)
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: D1422/D1422M − 13 (Reapproved 2020)
Standard Test Method for
Twist in Single Spun Yarns by the Untwist-Retwist Method
This standard is issued under the fixed designation D1422/D1422M; 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.
1. Scope 2. Referenced Documents
2 3
1.1 This test method describes the determination of twist in 2.1 ASTM Standards:
single spun yarns when only an approximation of the true twist D123 Terminology Relating to Textiles
is required. D1059 Test Method for Yarn Number Based on Short-
Length Specimens
NOTE 1—For a more accurate method see Test Method D1423.
D1423 Test Method for Twist in Yarns by Direct-Counting
1.2 This test method is applicable to spun single yarns in
D2258 Practice for Sampling Yarn for Testing
continuous lengths, and also to spun yarns raveled from
D3888 Terminology for Yarn Spinning Systems
fabrics,providedspecimensatleast200mm[8in.]longcanbe
D4849 Terminology Related to Yarns and Fibers
obtained.
3. Terminology
1.3 This test method has been found satisfactory for use in
determining the approximate twist content in single ring spun
3.1 Refer to Terminology D4849 for definitions of the
yarns of all types and fiber contents, but not in open-end spun
following terms used in this standard: direction of twist, single
yarns.
yarn, spun yarn, twist, twist factor, twist multiplier, and yarn.
1.4 This specification shows the values in both inch-pound
3.2 Refer toTerminology D123 andTerminology D3888 for
units and SI units. The “inch-pound” units is the technically
definitions of other terms used in this standard.
correct name for the customary units used in the United States.
4. Summary of Test Method
The “SI” units is the technically corrected name for the system
ofmetricunitsknownastheInternationalSystemofUnits.The
4.1 A specimen is untwisted and then retwisted in the
values stated in either SI units or inch-pound units are to be
opposite direction until it contracts to its original length. It is
regarded separately as standard. The values stated in each
assumedthatthesameamountoftwisthasbeeninsertedaswas
system are not necessarily exact equivalents; therefore, to
originally present. Twist, as turns per unit length, is calculated
ensure conformance with the standard, each system shall be
ashalfthenumberofturnsregisteredonthecounterdividedby
used independently of the other, and values from the two
the specimen length.
systems shall not be combined.
5. Significance and Use
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
5.1 This test method is used for acceptance testing in the
responsibility of the user of this standard to establish appro-
trade for economic reasons even though it is less accurate than
priate safety, health, and environmental practices and deter-
the direct method, Test Method D1423.
mine the applicability of regulatory limitations prior to use.
5.1.1 If there are differences or practical significance be-
1.6 This international standard was developed in accor-
tween reported test results for two laboratories (or more),
dance with internationally recognized principles on standard-
comparative tests should be performed to determine if their is
ization established in the Decision on Principles for the
a statistical bias between them, using competent statistical
Development of International Standards, Guides and Recom-
assistance.As a minimum, the test samples should be used that
mendations issued by the World Trade Organization Technical
are as homogeneous as possible, that are drawn from the
Barriers to Trade (TBT) Committee.
material from which the disparate test results are obtained, and
thatareassignedrandomlyinequalnumberstoeachlaboratory
for testing. Other materials with established test values may be
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.
Current edition approved Feb. 1, 2020. Published February 2020. Originally
approved in 1956. Last previous edition approved in 2013 as D1422 – 13. DOI: For referenced ASTM standards, visit the ASTM website, www.astm.org, or
10.1520/D1422_D1422M-13R20. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
This test method is commonly designated by the less precise term “Untwist- Standards volume information, refer to the standard’s Document Summary page on
Twist Method.” the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D1422/D1422M − 13 (2020)
used for this purpose.The test results from the two laboratories consideredonlyanapproximationoftheoriginalvaluebecause
should be compared using a statistical test for unpaired data, at of alterations that may have occurred as a result of the effects
a probability level chosen prior to the testing series. If a bias is ofunwinding,handling,andmechanicalstrainsmetinprocess-
found, either its cause must be found and corrected, or future ing.
test results must be adjusted in consideration of the known
bias. 6. Apparatus
5.2 The “setting” of twist in some fibers causes excessive
6.1 Twist Tester,consistingofapairofclamps,oneofwhich
contraction when the yarn is retwisted in the reverse direction.
is rotatable in either direction and positively connected to a
Therefore, the number of turns required to bring the specimen
revolution counter. The tester may be hand- or power-driven.
back to its original length may be less than the number of turns
The position of one clamp (or both clamps) shall be adjustable
removed in untwisting. This effect may be partially offset by
to accommodate specimens having the length prescribed in
the use of higher pretensioning loads; but this increases the
10.2. The tester shall be provided with a variable tensioning
danger of stretching the yarn. Little information is available on
devicesoconstructedthataspecificforcemaybeappliedtothe
the correct tensions to use for yarns made from different fibers
specimen at the beginning and end of the test and removed
or with different amounts of twist.
completely during the intervening untwisting and twisting
operations.
5.3 In addition to being less tedious, this test method
requires fewer specimens than the direct-counting method and
6.2 Dissecting needle or stylus.
the results may be sufficiently accurate for certain purposes.
6.3 Metal ruler to verify gauge length (accurate to 2 mm
This test method can be useful in those cases where the main
[0.1 in.]).
objective is to measure variations from an average value.
Another possible application is where a large amount of twist
7. Sampling
testing is required on yarns of similar type and twist. In this
case preliminary tests comparing this method and the direct 7.1 Lot Sample—Select one or more shipping units taken at
method could be used to determine the correct pretension.
random to represent an acceptance sampling lot and used as a
source of laboratory samples.
5.4 Twist has important effects on the physical properties of
yarn. Low-twist yarn is lofty and is usually preferred for
7.2 Laboratory Sample—For packaged yarns, take a mini-
knitting because of its softness, covering power, and warmth.
mum of five packages for the laboratory sample unless
Increasing the amount of twist causes an increase in yarn
otherwise agreed upon between purchaser and seller. For yarns
strength by increasing fiber cohesion, but as the twist angle
from woven or knitted fabrics, the sample must be large
increases beyond an optimum point, strength decreases due to
enough to furnish specimens of the length and number speci-
a loss in effective fiber contribution. Maximum yarn strength is
fied in 7.3.3.
obtained by inserting a medium amount of twist to obtain an
7.3 Selection of Specimens:
optimum balance between these two opposing forces. High
7.3.1 As nearly as possible take an equal number of speci-
twist produces yarns of high density (“hard” or “wiry”) and
mens from each package or unit of the laboratory sample.Take
high elongation and may improve the abrasion and impact
the specimens from each package in a random manner to
resistance of fabrics.
minimize the effect of cyclic variations introduced during
5.5 The optimum twist for either manufacturing efficiency
manufacturing processes. When preparing specimens, condi-
or physical properties usually increases as staple length de-
tioning them, or inserting them in the tester, take care to avoid
creases.
any change in twist.
5.6 The twist in a yarn before it is packaged may be 7.3.2 For packaged yarns, remove and discard the first 25 m
different from that of the yarn after it has been withdrawn from
[25 yd] of yarn. Using a minimum of tension, take specimens
the package because of changes in tension and the effect of the at random intervals greater than1m[1yd] along the yarn.
method of withdrawal. Withdraw the yarn from the package in
Withdraw the yarn from the package in the direction of normal
the direction of normal use, either from the side or over-end. If use, either from the side or over-end, if known. If the direction
the yarn is withdrawn over-end, a slight increase or decrease in is not known, withdraw the yarn from the side (Note 2). When
twist will take place, depending upon the direction of the twist more than five specimens are taken from an individual
in the yarn, the direction of winding on the package, and the package, take groups of five or less at intervals of several
length of the turn (or wrap) on the package. yards. Do not cut the specimen free from the package or from
the yarn to be discarded until after the yarn is secured in the
NOTE 2—The difference in twist between unwinding from the side and
clamps of the twist tester. When possible, take the specimen
over-end is 1/πd, where d is the diameter of the package. Thus, for a
from near the center of the traverse and not at the traverse
25-mm [1-in.] diameter package, the difference would be about 13 tpm or
about one third tpi.
reversals.
7.3.3 For woven fabric, take warp specimens from separate
5.7 When a yarn is taken from a more complex yarn
structure or from a fabric, the resultant twist should be ends, since each represents a separate package. Because the
fabric may have been woven on any of a variety of looms
which are random quilling, sequential quilling or shuttleless,
Woods, H. J., “The Kinematics ofTwist, I,The Definition ofTwist,” Journal of
Textile Science, JTBIA, vol 4, 1931, 33–36. take filling specimens at random through the whole laboratory
D1422/D1422M − 13 (2020)
Preliminary tensions in the range from 2.5 to 5.0 mN/tex [0.25 to 0.5
sample to obtain as representative data as possible. If a strip
gf/tex] may be tried.
about2m[2yd] long is used as a source of specimens.
7.3.4 For weft-knit fabric known to be multi-feed, take 9.3.1 End-Tensioning Procedure—Secure one end of the
specimensfromsuccessivecoursesinoneportionoflaboratory specimen in the nonrotatable clamp and insert the other end of
sample. For weft-knit fabric known to be single-feed or for the yarn through the rotatable clamp leaving it open temporar-
which the type of feed is not known, take specimens at random ily. Pull the yarn extending through the open clamp until the
from the whole sample. pointer attached to the nonrotatable clamp has reached the
7.3.5 For warp-knit fabrics, cut a walewise strip from which predetermined position for the required tension. Tighten the
specimens can be raveled for testing as needed (Note 3). Cut rotatable clamp securely while the pointer is in this position.
strips from which the test specimens can be raveled for testing Cutoffthelongendoftheyarn,leavinglessthan25mm[1in.]
as needed (Note 4). Cut these strips to provide yarn specimens protruding through the rotatable lamp. Revolve the rotatable
at least 75 mm [3 in.] longer than the specimen length and to clamp in the direction which untwists the specimen, releasing
contain more than the required number of specimens for test. If thetensionassoonasthespecimenstartstoelongate.Continue
several strips are cut, divide the number of specimens among the rotation in the same direction, removing the original twist
the strips as nearly equally as possible. Use care to avoid loss and imparting twist to the specimen in the direction opposite to
of twist prior to testing. the original twist. Reapply the tension when sufficient turns
have been reinserted to prevent slippage of the fibers. Continue
NOTE 3—In order to minimize changes in twist, specimens should not
to reinsert twist until the indicator has returned to its initial
be unraveled from the strips until they are to be placed in the twist tester.
position, when the specimen is assumed to have its original
7.4 Number of Specimens:
length and tension.
7.4.1 Spun Yarn Singles—Take 25 specimens from each
9.3.2 Standard Deflection Procedure—Position the single
laboratory sampling unit of spun yarn singles.
end twist attachment and adjust the upper base line before
starting. Secure one end of the specimen in the nonrotatable
8. Conditioning
clamp and insert the other end of the yarn through the open
8.1 Conditioning is not required for this test method.
rotatable clamp. Apply the selected tension (Note 5)tothe
approximatemidpointofthespecimen.Pullorslackentheyarn
9. Procedure
extendingthroughtheopenclampuntiltheyarnsagsadistance
of 3 mm [0.125 in.] from the horizontal at the point of
9.1 To Determine Twist:
applicationoftheload.Tightentherotatableclampandremove
9.1.1 Check the twist tester to be sure that the longitudinal
the applied load from the specimen. Cut off the long end of the
play and radial play of the clamp assemblies are small enough
yarn, leaving less than 25 mm [1 in.] protruding back of the
to secure the required precision.
rotatable clamp. Revolve the rotatable clamp in the direction
9.1.2 Determine the twist with the precision stated in the
which untwists the specimen, continuing the rotation in the
following table:
samedirectionbeyondthezerotwistreading.Whenasufficient
Turns of Twist in Test Specimen Precision, in
number of turns have been inserted to prevent slippage of the
(tpm or tpi) × Length (metres or inches) revolutions
fibers, reapply the tensioning load and continue twisting unti
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