1、BRITISH STANDARD BS ISO 6939:1988 Textiles Yarns from packages Method of test for breaking strength of yarn by the skein method ICS 59.080.20 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBS ISO 6939:1988 This British Standard, having been prepared under the direction of the
2、Materials and Chemicals Sector Policy and Strategy Committee, was published under the authority of the Standards Policy and Strategy Committee on 20 May 2002 BSI 20 May 2002 ISBN 0 580 39664 9 National foreword This British Standard reproduces verbatim ISO 6939:1988 and implements it as the UK natio
3、nal standard. It supersedes BS 6372:1983 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee TCI/24, Physical testing of textiles, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its sec
4、retary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standar
5、ds Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to
6、 understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document co
7、mprises a front cover, an inside front cover, ISO title page, pages ii and iii, a blank page, pages 1 to 4, an inside back cover and a back cover. The BSI copyright date displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date Comments
8、INTERNATIONAL STANDARD 6939 Second edition 1988-10-15 - ZE = = -ZZ = = = = = = = = E = :aiiE = E = - I 5 ZZ G = INTERNATIONAL ORGANIZATION FOR STANDARDIZATION ORGANISATION INTERNATIONALE DE NORMALISATION MEX,4YHAPOAHAR OPrAHM3AMR I-IO CTAHflAPTM3AqMM Textiles - Yarns from packages - Method of test f
9、or breaking strength of yarn by the skein method Textiles - Fils SW enroulemen ts - DtStermination de Ia rhsistance de rupture dun fil par Ia I rnh thode de lbchevette ISO Reference number ISO 6939 : 1988 (E) ISO 6939 : 1988 (El Foreword ISO (the International Organization for Standardization) is a
10、worldwide federation of national Standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Esch member body interested in a subject for which a technical committee has been established has the right to be represented
11、 on that committee. International organizations, govern- mental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards a
12、dopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the ISO Council. They are approved in accordance with ISO procedures requiring at least 75 % approval by the member bodies voting. International Standard ISO 6939
13、 was prepared by Technical Committee ISO/TC 38, Textiles. This second edition cancels and replaces the first edition (ISO 6939 : 1982), of which it constitutes a minor revision. Annex A forms an integral part of this International Standard. detnirP ni dnalreztiwS ii ISO 6939:1988 EI Introduction The
14、 skein method of testing yarn strength was developed very early in the history of textile testing. 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,
15、 the skein test is still widely used in some countries for some types of yarn. This method is not intended to Substitute for the measurement of breaking strength by the Single Strand method (ISO 2062). lt is intended to provide an additional method for measurement of yarn strength since the Single S
16、trand method is costly, time consuming and relatively difficult to control precisely in industrial situations. lt 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 whic
17、h tan be very useful in plants which spin yarn and manufacture fabrics. This method is not recommended as a reference test method. The skein method is essentially comparative when tests are made on similar yarns. lt is useful in control Programmes in which yarns made from the same fibre are tested p
18、eriodically and it is important that test conditions are as near identical as possible. Results 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. lt should be noted that th
19、e tenacity of a yarn measured in skein form is always less than tenacity obtained by the Single 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 eac
20、h Strand, and yarn-to-yarn cohesion. Details of a sampling procedure are given in annex A. This page intentionally left blank INTERNATIONAL STANDARD ISO 6939 : 1988 (E) Textiles - Yarns from packages - Method of test for breaking strength of yarn by the skein method 1 Scope This International Standa
21、rd specifies a method for the deter- mination of the breaking strength of yarn by the skein method. lt is applicable to spun Single and folded yarns of any fibre or mixture of fibres manufactured by any spinning System. lt is not recommended for testing filament yarns; for testing glass yarns; for m
22、ore 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 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 ev
23、en 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 density. 2 Normative references The following Standards contain provisions which, through reference in this text, constitute prov
24、isions 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 this International Standard are encouraged to investigate the possibility of applying the most recent editions of the Standa
25、rds listed below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 139 : 1973, Textiles - Standard atmospheres for condi- tioning and tes ting. ISO 2060 : 1972, Textiles - Yarn from packages - Determina- tion of linear density (mass per unit length) - Skein m
26、ethod. ISO 2062 : 1972, Textiles - Yarn from packages - Method for determination of breaking load and elongation at the breaking load of Single Strands (CRL, CRE and CRT testers). 3 Definitions For the purposes of this International Standard, the following definitions apply. 3.1 breaking strength: T
27、he maximum tensile forte 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 a large circumference in Proportion to its thickness. 3.3 test skein: A small skein which has a prescribed length of yarn
28、 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 of the breaking strength to the linear density of the unstrained specimen, usually expressed in centinewtons per tex. 3.5
29、 skein breaking tenacity: The maximum tensile stress developed in a test skein before rupture, expressed in forte per unit linear density of the yarn; for example, centinewtons per tex. 4 Principle A test skein is broken on a tensile testing machine and the breaking strength is observed. If the line
30、ar density is required for the calculation of skein breaking tenacity, the broken skein may be weighed and the linear density calculated according to ISO 2060. 5 Apparatus 5.1 Ree1 : a hand- or motor-driven reel, having a perimeter of 1 m. This reel shall be fitted with a traversing mechanism that w
31、ill 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 number of turns is desirable. If linear density is to be determined from the same skeins, refer to ISO 2060 for additional
32、 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 spindles for bobbins or cones (usually provided as an integral part of the reel); shafts on which tubes or flanged spoo
33、ls tan turn freely; heavy sup- ports for beams. 5.3 Tensile testing machine : a constant-rate-of-traverse or constant-rate-of-extension testing machine of suff icient capacity to break the test skeins and capable of operating so that the 1 ISO 6939 : 1988 (El moving clamp has a uniform Speed of 300
34、mm/min to directions, if any, given in the b) according to procedures approved by ISO for textile products, if directions on sampling are not included in the material specification ; c) according to the nor b) is applicable. method given in a nnex A if neither a) 7.2 The bulk Sample shall be taken i
35、n such a manner that it is representative of the lot to be tested. The laboratory Sample shall 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
36、to provide yarn for all tests required. 7.3.1 For yarns on bobbins, cops, cones, or similar 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 o
37、ther packages normally unwound from the side, mount the packages so as to turn freely, and 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 gu
38、ide, and reel a skein from each end. 7.3.4 If the yarn is received in skein form, mount it on an umbrella reel or swift, and reel at a Speed of 20 min -1 to 30 min-l. 7.3.5 When the yarn is on following manner: beams, prepare the yarn in the Place the beam containing the yarn to be tested on two bea
39、r- ings high enough so that the flanges of the beam clear the floor. Attach a trank arm to 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
40、from the beam to the reel. Let one Operator turn the beam slowly to unwind the yarn while a 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 ISO 2062 may be more appropriate and easier to emplo
41、y for yarn on beams. 7.4 Condition the laboratory Sample skeins as follows: 7.4.1 If linear 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,
42、 or for yarns on which linear density is not to be measured, bring the skeins to moisture equilibrium 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 0,l % in successive exposures of at least 30 min
43、 duration. 7.5 The follows : number of specimens to be be as 7.5.1 Test one skein 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
44、of test specimens according to the equation n = 0,17 v2 where n is the number of specimens; v is the coefficient of Variation of individual test determined from past records on similar material. NOTE - With a 90 % probability that the true mean of the lot is within + 4 % of the test average, there i
45、s a 5 % probalility that it is outside these limits on the high side and 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 ISO 6939 : 1988 (EI 7.5.2 lf v is not known, test 10 skeins of yarns spun on th
46、e 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 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. Knowl
47、edge of the v actually applicable is therefore likely to permit making fewer tests than prescribed in this sub-clause. 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 th
48、e spools mentioned in 5.3. Break the skein and record the breaking strength to the nearest 1 N if the breaking strength is under 500 N, or to the nearest 5 N if the breaking strength is 500 N or greater. Record the time to break, if required. NOTE - When using testing machines with autographic recor
49、ding equipment, the breaking strength and time to break may be read or calculated from the Chart. 7.5.3 Reel at least two extra skei ns for brea k if this optional procedure is used. adjustment of time to 9.4 If the skein breaking tenacity is to be calculated, determine the mass, in grams, of each broken skein. Calculate the yarn linear density in tex by multiplying the average mass by 10. 8 Preparation of test skeins NOTE - Additional information tan be found in ISO 2060. on the measu remen t of linear density 8.1 Mount each conditioned laboratory equipment to facili tate easy
