1、Designation: D2524 13Standard Test Method forBreaking Tenacity of Wool Fibers, Flat Bundle Method18-in. (3.2-mm) Gage Length1This standard is issued under the fixed designation D2524; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、 the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the break-ing tenacity of wool fibers as a flat bundle with
3、a18-in.(3.2-mm) clamp separation.1.2 This test method is especially adapted to the fiber bundleclamps and strength testing instruments specified, but may beused on other tensile testing machines when equipped withappropriate adapters to accommodate the prescribed clamps.1.3 This test method is appli
4、cable to wool in any formwhich can be hand-combed into small bundles of parallelizedfibers.NOTE 1Other test methods for measuring breaking tenacity of fiberbundles include Test Methods D1294, D1445, and D540.1.4 The values stated in inch-pound units are to be regardedas standard. The values given in
5、 parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.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
6、-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D123 Terminology Relating to TextilesD540 Methods of Testing Man-Made Staple Fibers; Re-placed by D 3660 (Withdrawn 1973)3D1294 Test Method for Tensi
7、le Strength and Breaking Te-nacity of Wool Fiber Bundles 1-in. (25.4-mm) GageLengthD1445 Test Method for Breaking Strength and Elongation ofCotton Fibers (Flat Bundle Method)D1776 Practice for Conditioning and Testing TextilesD4845 Terminology Relating to WoolD2525 Practice for Sampling Wool for Moi
8、sture3. Terminology3.1 For all terminology related to D13.13, Wool and Felt,see Terminology D4845.3.1.1 The following terms are relevant to this standard:breaking tenacity, constant-rate-of-extension (CRE) type ten-sile testing machine, constant-rate-of-loading (CRL) type ten-sile testing machine, c
9、onstant-rate-of-traverse (CRT) type ten-sile testing machine, gage length, tenacity, wool.3.2 For definitions of all other textile terms see TerminologyD123.4. Summary of Test Method4.1 A bundle of fibers is combed until parallel, placed undera uniform tension sufficient to remove as much crimp aspo
10、ssible without stretching the fibers, and secured in specialclamps. The fibers are then cut to a known length, broken in thetensile testing machine, removed from the clamps, andweighed. Breaking tenacity is calculated from the ratio ofbreaking force to bundle linear density. The length measuredunder
11、 the applied tension is the basis for computing lineardensity from bundle mass.5. Significance and Uses5.1 Test Method D2524 for testing wool fibers for tenacityis considered satisfactory for acceptance testing when theparticipating laboratories, using a reference wool, have shownacceptable between-
12、laboratory precision. It is recommendedthat any program of acceptance testing be preceded by aninterlaboratory check in the laboratory of the purchaser and thelaboratory of the seller on replicate specimens of samples ofthe material to be evaluated. In cases of dispute, the statisticalbias, if any,
13、between the laboratory of the purchaser and theseller should be determined with each comparison being basedon testing randomized specimens from one sample of materialof the type being evaluated.1This test method is under the jurisdiction of ASTM Committee D13 on Textilesand is the direct responsibil
14、ity of Subcommittee D13.13 on Wool and Felt.Current edition approved July 1, 2013. Published August 2013. Originallyapproved in 1966. Last previous edition approved in 2008 as D2524 95 (2008).DOI: 10.1520/D2524-13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM C
15、ustomer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, 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 C70
16、0, West Conshohocken, PA 19428-2959. United States15.2 Values obtained from flat bundle tenacity show a goodcorrelation with values obtained from single fiber tests andrequire much less time.5.3 The basic differences between the procedures describedin Test Method D2524 and those described in Test Me
17、thodD1294 lie in the manner of clamping the bundles and theshorter gage length employed. The special clamps used in thismethod allow quicker and easier bundle preparation; however,for Test Method D1294 no special clamps are required. Closeragreement with single fiber tenacity is also obtained with T
18、estMethod D2524 than when using the procedure in Test MethodD1294.5.4 As the observed tenacity of fibers depends in part on thetype of tensile testing machine used and the time required tobreak the specimen, results obtained with the different types ofmachines which may be used in this method will n
19、ot neces-sarily agree. The machines specifically designed for bundletesting are CRL testers which operate at a loading rate of 1kgf/s and therefore reach the breaking force at variable times inthe order of 5 s. CRE and CRT type machines would beexpected to produce somewhat different results not only
20、because of the inherent difference in operation but becauseCRE and CRT type machines are to be operated at a rate toachieve the breaking load in 20 s.6. Apparatus and Materials6.1 Tensile Testing Machine, having a capacity of at least 7kgf (70 N), equipped to accommodate the specified flat bundlecla
21、mps. For CRL testing machines,4the rate of loading isspecified as 1 kgf/s (10 N/s). For CRE and CRT machines,select a rate of operation which will reach the breaking force inan average time of 20 6 3s.6.1.1 In case the CRE or CRT testing machine is not capableof operating as specified in 6.1, select
22、 a rate so as to reach thebreaking force in an average time as close to 20 s as possibleand report the average time to break.NOTE 2There may be no overall correlation between the resultsobtained with the CRE, CRT or CRL type testing machines. Consequently,these three machines cannot be used intercha
23、ngeably.6.2 Balance, suitable for weighing 2 to 6 mg with asensitivity of 0.02 mg.6.3 Flat Bundle Clamps and Accessories, including thefollowing components:NOTE 3Pressley clamps and accessories have been found satisfactoryfor this purpose.5Adapters to fit the clamps to various tensile testinginstrum
24、ents are also available or can be fabricated.6.3.1 Clamps, having a total thickness of 0.465 6 0.001 in.(11.8 6 0.03 mm) and a 0.125 6 0.001-in. (3.2 6 0.03-mm)spacer.6.3.2 Clamp Vise, with a device to indicate approximately 8lbfin. (0.9 Nm) torque.6.3.3 Clamp Wrench.6.4 Coarse Comb, approximately 8
25、 teeth per in. (3 per 10mm).6.5 Fine Comb, approximately 50 teeth per in. (20 per 10mm).6.6 Black Paper, to hold bundles.6.7 Shearing Knife or Razor Blade.6.8 Tweezers.6.9 Torque Wrench or Friction Disk Wrench, to indicateapproximately 8 lbfin. (0.9 Nm) torque (optional).6.10 Standard Wool Top Sampl
26、e6, having an assigned break-ing tenacity of 11.4 gf/tex (112 mN/tex).NOTE 4The standard wool top sample, USDA Lot 58-27, has abreaking tenacity (based on single fiber tests) of 11.4 6 0.6 gf/tex, at the95 % probability level.7. Sampling7.1 Division into LotsTreat a single shipment of a singlefiber
27、type as a lot.7.2 Lot SampleAs a lot sample for acceptance testing, takeat random the number of shipment containers directed in anapplicable material specification or other agreement betweenthe purchaser and the supplier, such as an agreement to usePractice D2525. Consider shipping containers to be
28、the pri-mary sampling units.7.3 Laboratory SampleFor acceptance testing, take alaboratory sample from each shipping container in the lotsample as follows:7.3.1 For loose fiber, grease, and scoured wool, reduce themass of clean fiber submitted for testing to approximately 15 gby randomly selecting pi
29、eces throughout the mass. Form into aloose sliver by hand.7.3.2 For card sliver and top, cut a length of sliver about 20in. (500 mm) long from each ball submitted for testing.7.3.3 For roving, cut a length about 20 in. (500 mm) longfrom each spool submitted for testing and include all ends.7.4 Test
30、SpecimensScour or solvent-extract the laboratorysample until residual contamination is 1 % or less of thelaboratory mass, as established by further cleaning of a part ofthe laboratory sample. From each unit in the laboratory sample,prepare five test specimens as directed in 10.1.8. Preparation, Cali
31、bration, and Verification ofApparatus8.1 Tensile Testing MachineCheck the calibration of theinstrument according to the manufacturers instruction.4The sole source of supply for the Stelometer known to the committee at thistime is Special Instruments Laboratory, Inc., 312 W. Vine St., Knoxville, TN 3
32、7901.If you are aware of alternative suppliers, please provide this information to ASTMInternational Headquarters. Your comments will receive careful consideration at ameeting of the responsible technical committee,1which you may attend. TheClemson Tester (no longer available) have been found satisf
33、actory for this purpose.5The sole source of supply of the apparatus known to the committee at this timeis J. M. Doebrich and Co., P. O. Box 2789, Tucson, AZ 85702. If you are aware ofalternative suppliers, please provide this information to ASTM InternationalHeadquarters. Your comments will receive
34、careful consideration at a meeting of theresponsible technical committee,1which you may attend.6Available from the Wool and Mohair Laboratory, Livestock and Seed Division,AMS, U.S. Department of Agriculture, 711 “O” Street, Greeley, CO 80631.D2524 1328.2 BalanceCheck the zero reading and the sensiti
35、vity inthe range to be used.9. Preconditioning and Conditioning9.1 Bring the laboratory sample to moisture equilibrium fortesting in the standard atmosphere for testing as directed inPractice D1776.10. Preparation of Specimens10.1 Prepare each specimen by drawing small groups offibers from at least
36、five locations in a unit of the laboratorysample. Parallelize and combine them in a bundle which maybe held conveniently between the thumb and forefinger. De-pending on fiber entanglement, take a sufficient number offibers so that, after combining, an aligned specimen of 2 to 6mg is available for te
37、sting.10.2 Grasp the tuft about one-fourth the distance from theend of the tuft with the thumb and forefinger or a fiber handvise7and comb the protruding end with the coarse comb toremove loose fibers and foreign material and to secure partialparallelization of the fibers. Reverse the tuft and repea
38、t thecombing on the other end.10.3 Grasp the partially parallelized tuft at both ends usingthe fingers of one hand, thumb and ring finger holding one endand middle and index fingers holding the other end. Completethe parallelization of the fibers in the tuft by combing with thefine comb; with each p
39、ass of the comb release the end of thetuft toward which the comb is moving and grasp againimmediately after the comb passes the holding position. Toavoid moisture transfer from fingers to fibers, do not handle themiddle section of the tuft. If the specimen is estimated to be tooheavy, remove fibers
40、during the combing operation from eitherside with the tip of the comb to obtain the correct specimensize. The specimen is now ready to be placed in the clamps.11. Procedure11.1 Test the conditioned specimens in the standard atmo-sphere for testing.11.2 Inspect the leather faces of the clamps frequen
41、tly toensure that they are in good condition. Keep the inner edges ofthe leathers trimmed flush with the metal surfaces and replacethe leathers as soon as grooves become evident to the touch.11.3 Place the parallelized specimen (10.3) in the clamps inthe following manner: Using a Pressley type vise,
42、 lock theclamps with a18-in. (3.2-mm) spacer separating the clamps ofthe vise and open the jaws of the clamps. Hold both ends of thespecimen as directed in 10.3, keeping the specimen approxi-mately14 in. (6 mm) wide, and place it in the central part of theopen clamps. Maintain sufficient tension on
43、the specimen tohold the fibers straight while the jaws of the clamps arelowered and tightened in place by applying an 8 lbfin. (0.9Nm) torque. The torque may be controlled by either avise-mounted, torque-indicating instrument or by a frictiondisk wrench.11.4 Remove the clamps from the vise. Shear of
44、f theprotruding ends of the specimen with the shearing knife orrazor blade, cutting downward and away from the leather faceof the clamps and flush with the surface.11.5 Insert the loaded clamps in the tensile testing machineand break the test specimen in accordance with the manufac-turers instructio
45、ns. For other than the special instrumentsdesigned specifically for flat bundle testing, operate the testinstrument as directed in 6.1.11.6 After the specimen has been broken, record the break-ing force to the nearest scale or chart reading. Remove theclamps from the instrument and place the clamps
46、in the vise.Check to see that all fibers are broken. If all the fibers are notbroken, are broken irregularly indicating some slippage offibers in the clamps, or if the breaking force is less than therequired minimum for the instrument used, discard the speci-men and make a new test. If the break is
47、acceptable, open theclamps, collect all the broken fibers with tweezers, and weighto the nearest 0.02 mg (Note 5). To avoid gain in weight frommoisture pickup, do not touch the fibers with the fingers whilecollecting and weighing the specimen.NOTE 5If desired, the broken specimens may be stored temp
48、orarily inthe standard atmosphere for testing in folded black papers and weighedlater.11.7 Make a check test on a standard sample each daybefore making other tests and repeat the check after every tensamples to check the level of testing results. Calculate andrecord for each operator a correction fa
49、ctor based on resultssecured in tests made on the standard sample. Maintain aseparate record of each operators correction factors and use, asthe operators norm, the average of the last five factors tocorrect the next ten tests (Note 6). If a correction factor isobserved that differs by more than 5 % from the establishednorm, reject the factor and examine the instrument andtechnique carefully. Make any indicated adjustments to eitherthe instrument or the technique and make a new test on thestandard sample. If an abnormal factor is observed for thesecond time
