ASTM D1423 D1423M-2016 Standard Test Method for Twist in Yarns by Direct-Counting《用直接计数法测定纱线捻度的标准试验方法》.pdf

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1、Designation: D1423/D1423M 16Standard Test Method forTwist in Yarns by Direct-Counting1This standard is issued under the fixed designation D1423/D1423M; the number immediately following the designation indicates theyear of original adoption or, in the case of revision, the year of last revision. A nu

2、mber in parentheses indicates the year of lastreapproval. 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. Scope1.1 This test method covers the determination of the am

3、ountand direction of twist at the completion of any stage of twistingin single (spun or filament), plied, cabled, or novelty (exclusiveof long-term repeat patterns) yarns. The procedures are de-signed primarily for yarns in packages, but, with specialprecautions, they are applicable to yarns taken f

4、rom fabrics.The procedure for spun yarn in 9.2 is also applicable torovings.1.2 For plied yarns, this test method covers the determina-tion of the twist of the plied yarns and the twist of the singleyarn before plying. For cabled yarns, the test method covers thedetermination of the cable or hawser

5、twist; the twist of theplied yarn after plying, but prior to the last twisting operation;and the twist of the single yarn before plying. Procedures arealso included for the determination of the twists of the singleand plied yarn components as they lie in the final structure.Also, directions are incl

6、uded for the determination of twist inplied yarn made with direct cabling technology.1.3 This test method is not intended for yarns that extendmore than 5.0 % when tension is increased from 2.5 to 7.5mN/tex 0.25 to 0.75 gf/tex. Following the procedures of thistest method for such yarns would be inde

7、pendent of the biasand precision determined for this test method. The report fromsuch testing should include the tension used for this testing.1.4 UnitsThe values stated in either SI units or inch-pound units are to be regarded separately as standard. Thevalues stated in each system may not be exact

8、 equivalents;therefore, each system shall be used independently of the other.Combining values from the two systems may result in non-conformance with the standard.NOTE 1For a more rapid but less accurate method of determiningtwist in single spun yarns, refer to Test Method D1422.NOTE 2This test meth

9、od has been evaluated for use in determiningtwist in open end yarns and is not recommended.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practi

10、ces and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D123 Terminology Relating to TextilesD1059 Test Method for Yarn Number Based on Short-Length Specimens (Withdrawn 2010)3D1422 Test Method for Twist in Single Spun Yarns by theUntwis

11、t-Retwist MethodD1776 Practice for Conditioning and Testing TextilesD1907 Test Method for Linear Density of Yarn (Yarn Num-ber) by the Skein MethodD3888 Terminology for Yarn Spinning SystemsD4849 Terminology Related to Yarns and Fibers3. Terminology3.1 Refer to Terminology D4849 for definitions of t

12、hefollowing terms used in this standard: direction of twist, singleyarn, spun yarn, twist, twist factor, twist multiplier, and yarn.3.2 Refer to Terminology D123 and Terminology D3888 fordefinitions of other terms used in this standard.4. Summary of Test Method4.1 A specified length of specimen is m

13、ounted in a twistdevice. One end is rotated until all the elements are free oftwist. The number of turns is counted and the turns per unitlength are calculated.4.2 The amount of twist in the component elements of aplied or cabled yarn is determined by either of two options.4.2.1 In the procedure for

14、 determining original twist, oneend of the yarn is fixed while the other end is rotated until the1This test method is under the jurisdiction of ASTM Committee D13 on Textilesand is the direct responsibility of Subcommittee D13.58 on Yarns and Fibers.Current edition approved July 1, 2016. Published O

15、ctober 2016. Originallyapproved in 1956. Last previous edition approved in 2008 as D142302(2008).DOI: 10.1520/D1423_D1423M-16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information,

16、 refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1structural components are parallel. A

17、ny one or all of thesecomponents may then be used as test specimens.4.2.2 In the procedure for determining final twist incomponents, both ends of one component of the yarn are heldfixed while all the other components are removed and dis-carded. The twist is then determined in the remaining compo-nen

18、t.5. Significance and Use5.1 Test Method D1423 for testing twist in yarns bydirect-counting is considered satisfactory for acceptance test-ing of commercial shipments because current estimates ofbetween-laboratory precision are acceptable and the methodhas been used extensively in the trade for acce

19、ptance testing.5.1.1 If there are differences of practical significance be-tween reported test results for two laboratories (or more),comparative tests should be performed to determine if there isa statistical bias between them, using competent statisticalassistance. As a minimum use the samples for

20、 such compara-tive tests as homogeneous as possible, drawn from the same lotof material that resulted in the disparate test results andrandomly in equal numbers to each laboratory. The test resultsfrom the laboratories involved should be compared using astatistical test for unpaired data, at a proba

21、bility level chosenprior to the testing series. If a bias is found, either its causemust be found and corrected, or future test results for thatmaterial must be adjusted in consideration of the known bias.5.2 The determination of twist in a straight section of a yarnis not the simple straightforward

22、 operation it appears to be, forthe test results may be greatly influenced by variations in testprocedures and techniques. In all manipulations, extreme careis necessary to prevent specimen rotation altering the twistlevel before testing begins.5.3 The twist in a yarn before it is packaged may bedif

23、ferent from that of the yarn after it has been withdrawn fromthe package because of changes in tension and the effect of themethod of withdrawal. If the yarn is withdrawn over-end, aslight increase or decrease in twist will take place, dependingupon the direction of the twist in the yarn, the direct

24、ion ofwinding on the package, and the length of the wrap on thepackage.5.4 When a yarn is incorporated into or removed from amore complex structure, alterations may occur as a result of theplying, untwisting, or raveling operation. For example, whendetermining the twist in plied yarn by the procedur

25、e fordetermining original twist, as the plied yarn is untwisted, acomparable amount of twist is reinserted in, or removed from,the single-yarn components.As a consequence, the single yarnshave approximately the original twist prior to the plyingoperation but not the twist they have when they are fun

26、ctioningas components of the plied yarn. The latter or final twist maybe estimated by adding the ply twist to (or subtracting it from)the single-yarn twist depending on the directions of the ply andsingles twist. For a more precise determination, the testprocedure must be modified. There are thus tw

27、o differentprocedures for preparing specimens of the component elementsof a plied or cabled yarn for twist determination. The procedurefor the original twist measures the twist in a component of acomplex strand after the components have been untwisted. Theprocedure for final twist measures the twist

28、 in a component asit lies in the complex strand. Although the original twistprocedure is most often used, selection of a particular proce-dure will depend on the type of information needed.NOTE 3The difference in twist between unwinding from the side andover-end is 1/d, where d is the diameter of th

29、e package.4Thus, for a25-mm 1-in. diameter package, the difference would be about 13 tpm orabout13 tpi.5.5 When a yarn is taken from a more complex yarnstructure or from a fabric, the resultant twist should beconsidered only an approximation of the original value becauseof alterations that may have

30、occurred as a result of the effectsof unwinding, handling, and mechanical strains met in process-ing.5.6 The optimum amount of twist depends upon the use forwhich the yarn is intended. The amount of twist affects both thestrength and elongation properties of the yarn with increasedtwist being associ

31、ated with increased elongation. The relation-ship between twist and strength is more complex.5.6.1 In filament yarns, some twist up to 280 tpm 7 tpi ora suitable sizing is required to facilitate textile operations. Asmall increase in twist results in a slight increase in strength,but a further incre

32、ase results in a loss in strength. However,higher twist in such yarns may be used to subdue luster orincrease elongation, or to secure other special effects, as increpe fabrics.5.6.2 In conventional ring spun yarns a certain minimumamount of twist is necessary to bind or hold the individualfibers to

33、gether to produce a useful yarn. A limited increase intwist will result in an increase in strength until the critical twistlevel for the particular yarn involved has been reached, butfurther increase in twist results in a loss in strength.5.7 The same amount of twist in yarns of different sizes(diam

34、eter) will produce yarns with different degrees ofcompactness, twist character, and twist angles. The twistmultiplier or twist factor is approximately proportional to thetangent of the angle that the surface fibers make with the axisof the yarn. Therefore, the greater the angle, the greater thetwist

35、 multiplier. A constant twist multiplier indicates compa-rable compactness and degree of liveliness in yarns of differentsizes and conversely a difference in twist multiplier indicates adifference in compactness in yarns of the same size. Yarnsintended for different uses are frequently made with dif

36、ferenttwist multipliers, for example, warp yarns and filling yarns.5.8 Different cabling processes will influence the calcula-tion of twist from single component twist measurement. Thelength of cabled yarn before untwisting is used for thecalculation of twist for single components using direct cabli

37、ngtechnology. In case of 2 or more step twist technology thelength of the cabled yarn after untwisting is used for calcula-tion of the twist level in the single yarn components.4Woods, H. J., “The Kinematics of Twist, I, The Definition of Twist,” Journal ofTextile Science, Vol 4, 1931, pp 3336.D1423

38、/D1423M 1625.9 Twist multiplier and twist factor are a measure of the“twist hardness” of spun yarn because they are approximatelyproportional to the tangent of the angle between fibers on theouter yarn surface and the axis of the spun yarn; the larger thisangle, the harder the twist. Furthermore, th

39、is angle is a functionof both the twist content (turns per unit length) and the numberof fibers per yarn cross section (yarn number). Hence, twistcontent alone cannot provide a measure of the twist hardness ofa yarn.6. Apparatus6.1 Twist Tester, consisting of a pair of clamps, one of whichis rotatab

40、le in either direction and positively connected to arevolution counter. The tester may be hand- or power-driven.The position of one clamp (or both clamps) shall be adjustableto accommodate specimens of the lengths specified in 9.2 and9.3 and to permit measuring the change in length duringuntwisting.

41、 Means shall be provided for applying the specifiedtensions to the specimen and for determining the specimenlength with an accuracy of 60.5 mm 0.02 in. The movablebut nonrotatable clamp shall be capable of being traversed withsubstantially no friction to permit determining the untwistedlength of the

42、 specimen under the specified tension. Thecounting device shall be resettable to zero count and shallindicate the total number of turns to the nearest 0.1 turn.6.2 Dissecting Needle or Stylus.6.3 Gauge or Calipers.6.4 Magnifying Glass with Stand.6.5 Equipment for Reeling Laboratory Sample Skeins, op

43、-tional.7. Sampling and Test Specimens7.1 Lot SampleSelect one or more shipping units taken atrandom to represent an acceptance sampling lot and used as asource of laboratory samples.7.2 Laboratory Sampling UnitFrom each primary sam-pling unit, take a laboratory sample as specified in 7.2.1 and7.2.2

44、7.2.1 For packaged yarns, take a minimum of five packages.7.2.2 For rolls, take a full width of sufficient length that willprovide the 25 yarn specimens described in 7.3 and 7.4.7.3 Test Specimens:7.3.1 Spun Yarn SinglesTake 25 specimens from eachlaboratory sampling unit of spun yarn singles.7.3.2 F

45、ilament Yarn SinglesTake eight specimens fromeach laboratory sampling unit of filament yarn singles contain-ing 100 tpm or 2.5 tpi or less, and five specimens per laboratorysampling unit of filament yarn singles containing more than100 tpm or 2.5 tpi.7.3.3 Plied and Cabled YarnsTake five specimens p

46、erlaboratory sampling unit of plied and cabled yarns for eachcomponent to be tested.7.4 Selection of Specimens:7.4.1 Take an approximate equal number of specimens fromeach package or unit of the laboratory sample. Take thespecimens from each package in a random manner to minimizethe effect of cyclic

47、 variations introduced during the manufac-turing processes. When preparing specimens, conditioningthem or inserting them in the tester, take care to avoid anychange in twist.7.4.2 For packaged yarns, remove and discard the first 25 m25 yd of yarn. Using a minimum of tension, take specimensat random

48、intervals greater than1m1ydalong the yarn.Withdraw the yarn from the package in the direction of normaluse, either from the side or over-end, if known. If the directionis not known withdraw the yarn from the side (Note 3). Whenmore than five specimens are taken from an individualpackage, take groups

49、 of five or less at intervals of severalyards. Do not cut the specimen free from the package or fromthe yarn to be discarded until after the yarn is secured in theclamps of the twist tester. When possible, take the specimenfrom near the center of the traverse and not at the traversereversals.7.4.3 For woven fabric, take warp specimens from separateends, since each represents a separate package. Because thefabric may have been woven on any of a variety of loomswhich are random quilling, sequential quilling or shuttleless,take filling specimens at random throu