ASTM D1423-2002(2008) 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

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1、Designation: D 1423 02 (Reapproved 2008)Standard 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

2、. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () 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 a

3、mountand 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

4、from 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 inc

6、luded 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 i

7、ndependent of the 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. Th

8、e values stated in 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,

9、 refer to Test Method 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 t

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

11、 in Single Spun Yarns by theUntwist-Retwist MethodD 1776 Practice for Conditioning and Testing TextilesD 1907 Test Method for Linear Density of Yarn (YarnNumber) by the Skein MethodD 3888 Terminology for Yarn Spinning SystemsD 4849 Terminology Related to Yarns and Fibers3. Terminology3.1 Refer to Te

12、rminology 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 D 123 and Terminology D 3888for definitions of other terms used in this standard.4. Summary of Test Method

13、4.1 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 calculated.4.2 The amount of twist in the component elements of aplied or cabled yarn is determined by either of

14、 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 thesecomponents may then be used as test specimens.4.2.2 In the procedure for determining final twist in com-p

15、onents, both ends of one component of the yarn are held fixedwhile all the other components are removed and discarded. Thetwist is then determined in the remaining component.1This test method is under the jurisdiction of ASTM Committee D13 on Textilesand is the direct responsibility of Subcommittee

16、D13.58 on Yarns and Fibers.Current edition approved July 1, 2008. Published August 2008. Originallyapproved in 1956. Last previous edition approved in 2002 as D 1423 02.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annua

17、l Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5. Significance and Use5.1 Test Method D 1423 for testing twist in yarns bydi

18、rect-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 acceptance testing.5.1.1 If there are differences of practical significance be-twe

19、en 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 such compara-tive tests as homogeneous as possible, drawn from the same lotof

20、 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 probability level chosenprior to the testing series. If a bias is found, either its

21、 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 operation it appears to be, forthe test results may be greatly influenced by

22、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 bedifferent from that of the yarn after it has been withdrawn fromthe package becau

23、se 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 direction ofwinding on the package, and the length of the wrap on thepackage.5.4 Whe

24、n 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 procedure fordetermining original twist, as the plied yarn is untwisted, acomparable a

25、mount 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 functioningas components of the plied yarn. The latter or final twist maybe estim

26、ated 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 two differentprocedures for preparing specimens of the component elementsof a pl

27、ied 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 in a component asit lies in the complex strand. Although the original twistpr

28、ocedure 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/pd, where d is the diameter of the package.3Thus, for a25-mm (1-in.) diameter package, the difference would be

29、 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 occurred as a result of the effectsof unwinding, handling, and mechanical s

30、trains 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 associated with increased elongation. The relation-ship between twist and strengt

31、h 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 increase results in a loss in strength. However,higher twist in such yarns may

32、 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 together to produce a useful yarn. A limited increase intwist will result i

33、n 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(diameter) will produce yarns with different degrees of com-pactness, twist ch

34、aracter, and twist angles. The twist multiplieror 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 compactne

35、ssand degree of liveliness in yarns of different 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

36、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 cablingtechnology. In case of 2 or more step twist technology thelength of t

37、he cabled yarn after untwisting is used for calcula-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-drive

38、n.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 during3Woods, H. J., “The Kinematics of Twist, I, The Definition of Twist,” Journal ofTextile Science, Vol 4, 1931, pp 3336.D 1

39、423 02 (2008)2untwisting. 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 determinin

40、g the untwistedlength of the 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 Gage or Calipers.6.4 Magnifying Glass with Stand.6.5 Equipment for Reeling L

41、aboratory Sample Skeins, op-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

42、specified in 7.2.1 and7.2.27.2.1 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 o

43、f spun yarn singles.7.3.2 Filament 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

44、 YarnsTake five specimens perlaboratory 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 m

45、inimizethe effect of cyclic 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 m(25 yd) of yarn. Using a minimum of tens

46、ion, take specimensat random intervals greater than1m(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

47、 individual pack-age, take groups of five or less at intervals 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

48、 at the traverse reversals.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 through

49、 the whole laboratorysample to obtain as representative 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