ASTM D1423-2002 Standard Test Method for Twist in Yarns by Direct-Counting《直接计数法测定纱线捻数的标准试验方法》.pdf

1、Designation: D 1423 02Standard Test Method forTwist in Yarns by Direct-Counting1This standard is issued under the fixed designation D 1423; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in pare

2、ntheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This test method covers the determination of the amountand directio

3、n 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 from fabrics.The

4、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 twist; the twist

5、 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 included for the det

6、ermination 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 independent of the

7、 biasand precision determined for this test method. The report fromsuch testing should include the tension used for this testing.1.4 The values stated in either inch-pound or SI units are tobe regarded separately as standard. Within the text, the SI unitsare shown in parentheses. The values stated i

8、n each system arenot exact equivalents; therefore, each system shall be usedindependently of the other. Combining values from the twosystems may result in nonconformance within this test method.NOTE 1For a more rapid but less accurate method of determiningtwist in single spun yarns, refer to Test Me

9、thod D 1422.NOTE 2This test method 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

10、-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:D 123 Terminology Relating to Textiles2D 1059 Test Method for Yarn Number Based on Short-Length Specimens2D 1422 Test Method for Twist in Single Spun

11、Yarns by theUntwist-Retwist Method2D 1425 Test Method for Unevenness of Textile StrandsUsing Capacitance Testing Equipment2D 1776 Practice for Conditioning and Testing Textiles for2D 1907 Test Method for Yarn Number by the SkeinMethod2D 2258 Practice for Sampling Yarn for Testing2D 3888 Terminology

12、Relating to Open-End Spinning3D 4849 Terminology Relating to Fibers and Yarns33. Terminology3.1 Refer to Terminology D 4849 for definitions of thefollowing terms used in this standard: direction of twist, singleyarn, spun yarn, twist, twist factor, twist multiplier, and yarn.3.2 Refer to Terminology

13、 D 123 and Terminology D 3888for definitions of other terms used in this standard.4. Summary of Test Method4.1 A specified length of specimen is mounted 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 calcu

14、lated.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 determining original twist, oneend of the yarn is fixed while the other end is rotated until thestructural components are parallel. Any one or all of the

15、secomponents may then be used as test specimens.4.2.2 In the procedure for determining final twist in com-ponents, both ends of one component of the yarn are held fixed1This test method is under the jurisdiction of ASTM Committee D13 on Textiles,and is the direct responsibility of Subcommittee D13.5

16、8 on Yarn Test Methods,General.Current edition approved Sept. 10, 2002. Published November 2002. Originallypublished as D 1423 56 T. Last previous edition D 1423 99.2Annual Book of ASTM Standards, Vol 07.01.3Annual Book of ASTM Standards, Vol 07.02.1Copyright ASTM International, 100 Barr Harbor Driv

17、e, PO Box C700, West Conshohocken, PA 19428-2959, United States.while all the other components are removed and discarded. Thetwist is then determined in the remaining component.5. Significance and Use5.1 Test Method D 1423 for testing twist in yarns bydirect-counting is considered satisfactory for a

18、cceptance test-ing of commercial shipments because current estimates ofbetween-laboratory precision are acceptable and the methodhas been used extensively in the trade for acceptance testing.5.1.1 If there are differences of practical significance be-tween reported test results for two laboratories

19、(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 such compara-tive tests as homogeneous as possible, drawn from the same lotof material that resulted in the disparate test

20、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 probability level chosenprior to the testing series. If a bias is found, either its causemust be found and corrected, or future t

21、est 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 operation it appears to be, forthe test results may be greatly influenced by variations in testprocedures and techniques. I

22、n 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 bedifferent from that of the yarn after it has been withdrawn fromthe package because of changes in tension and the effect of the

23、method 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 direction ofwinding on the package, and the length of the wrap on thepackage.5.4 When a yarn is incorporated into or removed from

24、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 procedure fordetermining original twist, as the plied yarn is untwisted, acomparable amount of twist is reinserted in, or removed fr

25、om,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 functioningas components of the plied yarn. The latter or final twist maybe estimated by adding the ply twist to (or subtracti

26、ng 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 two differentprocedures for preparing specimens of the component elementsof a plied or cabled yarn for twist determination. T

27、he 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 in a component asit lies in the complex strand. Although the original twistprocedure is most often used, selection of a pa

28、rticular proce-dure will depend on the type of information needed.NOTE 3The difference in twist between unwinding from the side andover-end is 1/pd, where d is the diameter of the package.4Thus, for a25-mm (1-in.) diameter package, the difference would be about 13 tpm orabout13 tpi.5.5 When a yarn i

29、s 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 occurred as a result of the effectsof unwinding, handling, and mechanical strains met in process-ing.5.6 The optimum amo

30、unt 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 associated with increased elongation. The relation-ship between twist and strength is more complex.5.6.1 In filament yarns, so

31、me 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 increase results in a loss in strength. However,higher twist in such yarns may be used to subdue luster orincrease elongati

32、on, 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 together to produce a useful yarn. A limited increase intwist will result in an increase in strength until the critical

33、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(diameter) will produce yarns with different degrees of com-pactness, twist character, and twist angles. The twist multipli

34、eror twist factor is approximately proportional to the tangent ofthe angle that the surface fibers make with the axis of the yarn.Therefore, the greater the angle, the greater the twist multiplier.A constant twist multiplier indicates comparable compactnessand degree of liveliness in yarns of differ

35、ent sizes andconversely a difference in twist multiplier indicates a differencein compactness in yarns of the same size. Yarns intended fordifferent uses are frequently made with different twist multi-pliers, for example, warp yarns and filling yarns.5.8 Different cabling processes will influence th

36、e 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 cablingtechnology. In case of 2 or more step twist technology thelength of the cabled yarn after untwisting is used for c

37、alcula-tion of the twist level in the single yarn components.6. Apparatus6.1 Twist Tester, consisting of a pair of clamps, one of whichis rotatable 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)

38、shall be adjustableto accommodate specimens of the lengths specified in 9.2 and9.3 and to permit measuring the change in length during4Woods, H. J., “The Kinematics of Twist, I, The Definition of Twist,” Journal ofTextile Science, Vol 4, 1931, pp 3336.D1423022untwisting. Means shall be provided for

39、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 specimen under the specif

40、ied 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 Gage or Calipers.6.4 Magnifying Glass with Stand.6.5 Equipment for Reeling Laboratory Sample Skeins, op-tional.7. Sampling and Tes

41、t 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 and7.2.27.2.1 For packaged yarns, t

42、ake 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 Filament Yarn SinglesTake ei

43、ght 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 perlaboratory sampling unit

44、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 variations introduced duri

45、ng 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 m(25 yd) of yarn. Using a minimum of tension, take specimensat random intervals greater than1m(

46、1yd)along 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 individual pack-age, take groups of five or less at i

47、ntervals of several yards. Donot cut the specimen free from the package or from the yarn tobe discarded until after the yarn is secured in the clamps of thetwist tester. When possible, take the specimen from near thecenter of the traverse and not at the traverse reversals.7.4.3 For woven fabric, tak

48、e 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 through the whole laboratorysample to obtain as representativ

49、e data as possible. A stripabout2m(2yd)long is recommended as a source for fillingyarn specimens.7.4.4 For weft-knit fabric, known to be multi-feed, takespecimens from successive courses in one portion of laboratorysample. For weft-knit fabric known to be single-feed or forwhich the method of feed is not known take specimens atrandom from the whole laboratory sample.7.4.5 For warp-knit fabric, prepare specimens as directed inTest Method D 1059. Cut strips from which the test specimenscan be raveled for testing as needed (Note 4). Cut these stripsso as to provide yarn specime