ASTM D1422-99(2008)
(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
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 D 1423.
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.
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.
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 type and twist. In thi...
SCOPE
1.1 This test method 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 D 1423.
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 The values stated in either inch-pound or SI units are to be regarded separately as standard. Within the text, the SI units are shown in parentheses. The values stated in each system are not exact equivalents; therefore each system shall be used independently of the other. Combining values from the two systems may result in nonconformance within this test method.
1.4 This test method has been found satisfactory for use in determining twist in all single ring spun yarns and 100% cotton open-end yarns. For all open-end spun yarns that are not 100 % cotton this test method has not been found to be satisfactory for determining twist but may be used to measure deviation from an average value.
1.5 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 acceptable metric units or in other units shall be regarded separately as standard. The values expressed in each system may not be exact equivalents; therefore, each system must be used independently of the other, without combining in any way.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: D1422 − 99(Reapproved 2008)
Standard Test Method for
1
Twist in Single Spun Yarns by the Untwist-Retwist Method
This standard is issued under the fixed designation D1422; 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 and health practices and determine the applicability of regu-
2
latory limitations prior to use.
1.1 Thistestmethod describesthedeterminationoftwistin
single spun yarns when only an approximation of the true twist
2. Referenced Documents
is required.
3
2.1 ASTM Standards:
NOTE 1—For a more accurate method see Test Method D1423.
D123 Terminology Relating to Textiles
1.2 This test method is applicable to spun single yarns in
D1059 Test Method for Yarn Number Based on Short-
4
continuous lengths, and also to spun yarns raveled from
Length Specimens (Withdrawn 2010)
fabrics,providedspecimensatleast200mm(8in.)longcanbe
D1423 Test Method for Twist in Yarns by Direct-Counting
obtained.
3. Terminology
1.3 The values stated in either inch-pound or SI units are to
3.1 Definitions:
be regarded separately as standard.Within the text, the SI units
3.1.1 direction of twist, n—the right or left direction of the
are shown in parentheses. The values stated in each system are
helix formed in a twisted strand as indicated by superimposi-
not exact equivalents; therefore each system shall be used
tion of the capital letter “S” or “Z.”
independently of the other. Combining values from the two
3.1.1.1 Discussion—Yarn has S twist if, when the yarn is
systems may result in nonconformance within this test method.
held in a vertical position, the visible spirals or helices around
1.4 This test method has been found satisfactory for use in
its central axis conform in direction of slope to the central
determiningtwistinallsingleringspunyarnsand100%cotton
portion of the letter“ S,” and Z twist if the visible spirals or
open-endyarns.Forallopen-endspunyarnsthatarenot100 %
helices conform in direction of slope to the central portion of
cottonthistestmethodhasnotbeenfoundtobesatisfactoryfor
the letter “Z.” When two or more yarns, either single or plied,
determining twist but may be used to measure deviation from
are twisted together, the letters “S” and “Z” are used in a
an average value.
similar manner to indicate the direction of the last twist
1.5 This specification shows the values in both inch-pound
inserted.
units and SI units. The “inch-pound” units is the technically
3.1.2 single yarn, n—the simplest strand of textile material
correct name for the customary units used in the United States.
suitable for operations such as weaving, knitting, etc.
The “SI” units is the technically corrected name for the system
3.1.2.1 Discussion—A single yarn may be formed from
ofmetricunitsknownastheInternationalSystemofUnits.The
fibers with more or less twist; from filaments with or without
values stated in either acceptable metric units or in other units
twist; from narrow strips of materials such as paper,
shall be regarded separately as standard. The values expressed
cellophane,ormetalfoil;orfrommonofilaments.Ayarnwhich
in each system may not be exact equivalents; therefore, each
is either twistless or can be rendered twistless in a single
system must be used independently of the other, without
untwisting operation. When twist is present, it is usually all in
combining in any way.
the same direction.
1.6 This standard does not purport to address all of the
3.1.3 spun yarn, n—in a staple system, a continuous strand
safety concerns, if any, associated with its use. It is the
of fibers held together by some binding mechanism.
responsibility of this standard to establish appropriate safety
3.1.3.1 Discussion—The binding mechanism most com-
monly used in spun yarns is twist. Other useful mechanisms
1
This test method is under the jurisdiction ofASTM Committee D13 on Textiles
3
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 Aug. 1, 2008. Published October 2008. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1956. Last previous edition approved in 1999 as D1422 – 99. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D1422-99R08. the ASTM website.
2 4
This test method is commonly designated by the less precise term“ Untwist- The last approved version of this historical standard is referenced on
Twist Method.” www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Con
...
This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:D1422–99 Designation: D 1422 – 99 (Reapproved 2008)
Standard Test Method for
1
Twist in Single Spun Yarns by the Untwist-Retwist Method
This standard is issued under the fixed designation D 1422; 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
1.1 This test method 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 D 1423.
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 The values stated in either inch-pound or SI units are to be regarded separately as standard. Within the text, the SI units are
shown in parentheses. The values stated in each system are not exact equivalents; therefore each system shall be used
independently of the other. Combining values from the two systems may result in nonconformance within this test method.
1.4 This test method has been found satisfactory for use in determining twist in all single ring spun yarns and 100% cotton
open-end yarns. For all open-end spun yarns that are not 100 % cotton this test method has not been found to be satisfactory for
determining twist but may be used to measure deviation from an average value.
1.5 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 acceptable metric units or in other units shall be
regarded separately as standard. The values expressed in each system may not be exact equivalents; therefore, each system must
be used independently of the other, without combining in any way.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior
to use.
2. Referenced Documents
3
2.1 ASTM Standards:
D 123 Terminology Relating to Textiles
D 1059 Test Method for Yarn Number Based on Short-Length Specimens
3
D 1423Test Method for Twist in Yarns by the Direct-Counting Method
3
D2258Practice for Sampling Yarn for Testing Test Method for Twist in Yarns by Direct-Counting
3. Terminology
3.1 Definitions:
3.1.1 direction of twist, n—the right or left direction of the helix formed in a twisted strand as indicated by superimposition of
the capital letter “S” or “Z.”
3.1.1.1 Discussion—Yarn has S twist if, when the yarn is held in a vertical position, the visible spirals or helices around its
centralaxisconformindirectionofslopetothecentralportionoftheletter“S,”and Ztwistifthevisiblespiralsorhelicesconform
in direction of slope to the central portion of the letter “Z.” When two or more yarns, either single or plied, are twisted together,
the letters “S” and “Z” are used in a similar manner to indicate the direction of the last twist inserted.
3.1.2 single yarn, n—the simplest strand of textile material suitable for operations such as weaving, knitting, etc.
3.1.2.1 Discussion—Asingleyarnmaybeformedfromfiberswithmoreorlesstwist;fromfilamentswithorwithouttwist;from
1
This test method is under the jurisdiction ofASTM Committee D13 onTextiles, and is the direct responsibility of Subcommittee D13.58 onYarnTest Methods, General.
Current edition approved Nov. 10, 1999. Published January 2000. Originally published as D1422–56 T. Last previous edition D1422–92.
1
This test method is under the jurisdiction of ASTM Committee D13 on Textiles and is the direct responsibility of Subcommittee D13.58 on Yarns and Fibers.
Current edition approved Aug. 1, 2008. Published October 2008. Originally approved in 1956. Last previous edition approved in 1999 as D 1422 – 99.
2
This test method is commonly designated by the less precise term“ Untwist-Twist Method.”
3
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
, Vol 07.01.volume information, refer
...
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