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1、INTERNATIONAL STANDARD INTERNATIONAL ORGANIZATION FOR STANDARDIZATION ORGANISATION INTERNATIONALE DE NORMALISATION MEXAYHAPOAHAR OPAHM3AYMR fl0 CTAHAAPTMSAYMM Textiles - Yarns from packages - Method of test for breaking strength of yarn by the skein method Textiles - Fils sur enroulements - Dtermina
2、tion de la rsistance de rupture dun fil par la mthode de lchevette IS0 6939 Second edition 1988-10-15 Reference number IS0 6939 : 1988 (E) Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04
3、/27/2007 04:50:32 MDTNo reproduction or networking permitted without license from IHS -,-,- - 6939-88 3 Li851703 0053706 O I- IS0 939 : 1988 (E) Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of p
4、reparing International Standards is normally carried out through IS0 technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, govern- mental and non-governmental
5、, in liaison with ISO, also take part in the work. IS0 collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval
6、before their acceptance as International Standards by the IS0 Council. They are approved in accordance with IS0 procedures requiring at least 75 % approval by the member bodies voting. International Standard IS0 6939 was prepared by Technical Committee ISO/TC 38, Text;les, This second edition cancel
7、s and replaces the first edition (IS0 939 : 19821, of which it constitutes a minor revision, Annex A forms an integral part of this International Standard. 0 International Organization for Standardization, 1588 Printed in Switzerland ii Copyright International Organization for Standardization Provid
8、ed by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 04:50:32 MDTNo reproduction or networking permitted without license from IHS -,-,- Introduction The skein method of testing yarn strength was developed very early in the history of textile test
9、ing. Within recent decades the skein method has been supplanted to a large extent by the single strand method, especially since the development of automatic single strand strength testing machines. However, the skein test is still widely used in some countries for some types of yarn. This method is
10、not intended to substitute for the measurement of breaking strength by the single strand method (IS0 2062). It is intended to provide an additional method for measurement of yarn strength since the single strand method is costly, time consuming and relatively difficult to control precisely in indust
11、rial situations. It is particulary important when yarn is received as raw material that breaking strength be determined quickly. This method provides a means of comparative measurement of yarn strength which can be very useful in plants which spin yarn and manufacture fabrics. This method is not rec
12、ommended as a reference test method. The skein method is essentially comparative when tests are made on similar yarns. It is useful in control programmes in which yarns made from the same fibre are tested periodically and it is important that test conditions are as near identical as possible. Result
13、s from tests between laboratories have shown that a correlation exists between the tenacity of yarn measured by the skein method and tenacity measured by the single strand method. It should be noted that the tenacity of a yarn measured in skein form is always less than tenacity obtained by the singl
14、e strand method. The average skein strength depends not only on the strength of individual yarns, but also on breaking elongation, coefficient of variation of breaking elongation, the initial modulus of each strand, and yarn-to-yarn cohesion. Details of a sampling procedure are given in annex A. Cop
15、yright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 04:50:32 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD IS0 6939 : 1988 (EI Textile
16、s - Yarns from packages - Method of test for breaking strength of yarn by the skein method 1 Scope This International Standard specifies a method for the deter- mination of the breaking strength of yarn by the skein method. It is applicable to spun single and folded yarns of any fibre or mixture of
17、fibres manufactured by any spinning system. It is not recommended for testing filament yarns; for testing glass yarns; for more complex structures such as cabled yarns or cords; for yarns that stretch more than 5 % when the ten- sion increases from 0,5 cN to 1,0 cN per unit of linear density of the
18、yarn in tex; nor is it applicable to those yarns having a diameter so great as to prevent the winding of the skein in two even layers. With suitable precautions as to skein circumference and the tension used in reeling, the skeins broken in this test may be used for the determination of linear densi
19、ty. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on
20、this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards listed below. Members of IEC and IS0 maintain registers of currently valid International Standards. IS0 139 : 1973, Textiles - Standard atmospheres for condi- tioning and t
21、esting. IS0 2060 : 1972, Textiles - Yarn from packages - Determina- tion of linear density (mass per unit length) - Skein method. IS0 2062 : 1972, Textiles - Yarn frompackages - Method for determination of breaking load and elongation at the breaking load of single strands ICRL, CRE and CRT testers)
22、. 3 Definitions For the purposes of this International Standard, the following definitions apply. 3.1 breaking strength: The maximum tensile force ob- served during a test in which the specimen is stretched until it breaks. 3.2 skein: A continuous strand of yarn in the form of a flexible coil having
23、 a large circumference in proportion to its thickness. 3.3 test skein: A small skein which has a prescribed length of yarn and is used in this International Standard for the deter- mination of linear density or breaking strength or both; also called a lea or numbering skein. 3.4 tenacity: The ratio
24、of the breaking strength to the linear density of the unstrained specimen, usually expressed in centinewtons per tex. 3.5 skein breaking tenacity: The maximum tensile stress developed in a test skein before rupture, expressed in force per unit linear density of the yarn; for example, centinewtons pe
25、r tex. 4 Principle A test skein is broken on a tensile testing machine and the breaking strength is observed. If the linear density is required for the calculation of skein breaking tenacity, the broken skein may be weighed and the linear density calculated according to IS0 2060. 5 Apparatus 5.1 Ree
26、l: a hand- or motor-driven reel, having a perimeter of 1 m. This reel shall be fitted with a traversing mechanism that will space the yarn evenly on the reel in not more than two layers, and an indicator of the length wound. A warning bell or an automatic cutoff that will operate at the specified nu
27、mber of turns is desirable. If linear density is to be determined from the same skeins, refer to IS0 2060 for additional reel specifications. NOTE - Existing reels with perimeters other than 1 m may be used, if mutually agreed and, if used, this should be reported. 5.2 Yarn package holders: vertical
28、 spindles for bobbins or cones (usually provided as an integral part of the reel); shafts on which tubes or flanged spools can turn freely; heavy sup- ports for beams. 5.3 Tensile testing machine: a constant-rate-of-travetse or constant-rate-of-extension testing machine of cuff icient capacity to br
29、eak the test skeins and capable of operating so that the 1 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 04:50:32 MDTNo reproduction or networking permitted without license fro
30、m IHS -,-,- -3 4853903 0053709 b r IS0 6939 : 1988 (E) moving clamp has a uniform speed of 300 mm/min I 10 mm/min, or is capable of operating at such a rate that the skein is broken in an average time of 20 s f 3 s from the start of application of load to the skein, The option selected shall be by a
31、greement of all parties and shall be stated in the report of test results. The indicated load shall be accurate to within f 1,O % in the range used for the tests. If an autographic load- recording device is used, its maximum pen speed shall be at least double the rate at which the load on the skein
32、increases at the steepest part of the curve. The machine shall be equipped with spoofs 26 mm to 32 mm in both diameter and length, so supported that at least one spool can turn freely on its axis. The distance between the spools shall be sufficient to permit placing the skeins on the spools in a wid
33、e, flat band. 5.4 Skein holder or skein rack, having parallel pegs or bars placed a Sufficient distance apart to hold the skeins extended to nearly their full length, without either stretching the yarn or allowing kinking which would cause entanglement. 6 Atmospheres for pre-conditioning, conditioni
34、ng and testing The atmospheres for pre-conditioning, conditioning and testing shall be those defined in IS0 139. 7 Sampling 7.1 Samples shall be taken in one of the following ways: a) according to directions, if any, given in the material specifications; b) according to procedures approved by IS0 fo
35、r textile products, if directions on sampling are not included in the material specification; cl according to the method given in annex A if neither a) nor b) is applicable. 7.2 The bulk sample shall be taken in such a manner that it is representative of the lot to be tested. The laboratory sample s
36、hall be selected from the bulk sample in a representative manner. 7,3 Reel one laboratory sample skein from each laboratory sample package, using the lowest tension practicable. The skeins shall be long enough to provide yarn for all tests required, 7,3.1 For yarns on bobbins, cops, cones, or simila
37、r packages where the yarn is normally unwound overend, draw the yarn off over the end of the package at a rotational frequency between 100 min-1 and 300 min-1 of the reel, 7.3,2 For yarns on flanged spools or other packages normally unwound from the side, mount the packages so as to turn freely, and
38、 draw the yarn from the side of the package at a rotational frequency of 20 min - 1 to 30 min - 1 of the reel. 7.3.3 When several ends are wound parallel on a single package, draw each end through a separate guide, and reel a skein from each end. 7.3.4 If the yarn is received in skein form, mount it
39、 on an umbrella reel or swift, and reel at a speed of 20 min-1 to 30 min-1. 7.3.5 When the yarn is on beams, prepare the yarn in the following manner: Place the beam containing the yarn to be tested on two bear- ings high enough so that the flanges of the beam clear the floor. Attach a crank arm to
40、one end of the beam shaft. Place the reel a convenient distance from the beam and in such a position that the yarn is not drawn sidewise at an angle of more than 20 degrees. Fasten the required number of ends from the beam to the reel, Let one operator turn the beam slowly to unwind the yarn while a
41、 second operator turns the reel fast enough to take up the yarn as it comes from the beam. NOTE - The single strand method of yarn strength testing given in IS0 2062 may be more appropriate and easier to employ for yarn on beams. 7.4 Condition the laboratory sample skeins as follows: 7.4.1 If linear
42、 density is to be determined, pre-condition the laboratory sample skeins by exposing them to freely moving air in the special atmosphere for pre-conditioning for a minimum of 4 h. 7.4.2 After pre-conditioning, or for yarns on which linear density is not to be measured, bring the skeins to moisture e
43、quilibrium for testing by exposing them to the appropriate standard atmosphere for testing for 24 h or until there is no progressive change in mass greater than Oll % in successive exposures of at least 30 min duration. 7.5 The number of specimens to be tested shall be as follows : 7.5.1 Test one sk
44、ein per yarn package. In the absence of other specifications or agreement, choose a number of yarn packages that will give a precision of the mean of 4 % at a probability level of 90 % (see the note). Calculate the number of test specimens according to the equation n = 0,17 Y where n is the number o
45、f specimens; Y is the coefficient of variation of individual test results determined from past records on similar material. NOTE - With a 90 % probability that the true mean of the lot is within f 4 % of the fest average, there is a 5 % probalility that it is outside these limits on the high side an
46、d 5 % that it is out on the low side. Thus, there is a 95 % probability that the true mean is not more than 4 % below the mean of the test results. 2 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for
47、 Resale, 04/27/2007 04:50:32 MDTNo reproduction or networking permitted without license from IHS -,-,- 7.5.2 If v is not known, test 10 skeins of yarns spun on the cotton or worsted system and 20 skeins of yarns spun on the woollen system. These numbers of tests are based on v = 7,5 % for yarns spun
48、 on the cotton and worsted systems and on v = 11 ,O % for woollen-system yarns. These values of v are somewhat higher than will usually be found in practice. Knowledge of the v actually applicable is therefore likely to permit making fewer tests than prescribed in this sub-clause. 7.5.3 Reel at leas
49、t two extra skeins for adjustment of time to break if this optional procedure is used. 8 Preparation of test skeins IS0 6939 : 1988 (E) 9.3 Transfer each skein separately to the testing machine without twisting the skein or allowing it to collapse. Mount the skein in such a manner that it lies as a flat ribbon on the spools mentioned in 5.3. Break the skein and record the breaking streng