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1、BRITISH STANDARD BS ISO 16549:2004 Textiles Unevenness of textile strands Capacitance method ICS 59.060.01 ? Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 02:04:49 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS ISO 16549:2004 This British Standard was published under the authority of the Sta
2、ndards Policy and Strategy Committee on 9 February 2005 BSI 9 February 2005 ISBN 0 580 45397 9 National foreword This British Standard reproduces verbatim ISO 16549:2004 and implements it as the UK national standard. The UK participation in its preparation was entrusted to Technical Committee TCI/24
3、, Textiles Physical testing, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international publications referred to in this document may be found in the BSI Cata
4、logue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its co
5、rrect application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests i
6、nformed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the ISO title page, pages ii to v, a blank page, pages 1 to 10, an inside back cover and a back cover. The BSI copyright noti
7、ce displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. DateComments Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 02:04:49 GMT+00:00 2006, Uncontrolled Copy, (c) BSI INTERNATIONAL STANDARD ISO 16549 First edition 2004-06-01 Re
8、ference number ISO 16549:2004(E) Textiles Unevenness of textile strands Capacitance method Textiles Irrgularit des fils textiles Mthode capacitive BS ISO 16549:2004 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 02:04:49 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii id FDPscalimer ThFDP si f
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14、 Page 1Scope 1 2Normative references 1 3Terms and definitions 1 4Principle 2 5Apparatus . 3 6Atmosphere for conditioning and testing . 4 7Sampling . 4 8Procedure . 5 9Calculations and expression of results . 6 10Test report 6 Annex A (informative) Other methods for the determination of unevenness .
15、8 Bibliography . 10 BS ISO 16549:2004 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 02:04:49 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work o
16、f preparing International Standards is normally carried out through ISO 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, governmental and non-governmenta
17、l, 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. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main
18、 task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Atte
19、ntion is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 16549 was prepared by Technical Committee ISO/TC 38, Textiles, Subcommittee SC 23, Fibres and yarns.
20、This International Standard cancels and replaces ISO 2649 which is now obsolete. BS ISO 16549:2004 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 02:04:49 GMT+00:00 2006, Uncontrolled Copy, (c) BSI v Introduction In the 1960s the International Wool Textile Organization (IWTO) prepared an une
21、venness method destined for yarns and other strands made of wool. The method was adopted by ISO as ISO 2649:1974. It contains a discussion of the principles of unevenness testing and refers to the then-popular unevenness tester, the 1960s model of the Uster Evenness Tester, which was obsolete in mid
22、-2000 when the present International Standard was written. Later, the IWTO prepared a new method, IWTO-18-00, published in 2000. ISO 16549 has mostly new wording but includes some elements of ISO 2649 and of IWTO-18-00 with thanks to IWTO. BS ISO 16549:2004 Licensed Copy: sheffieldun sheffieldun, na
23、, Mon Nov 27 02:04:49 GMT+00:00 2006, Uncontrolled Copy, (c) BSI . iv Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 02:04:49 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ANRETNIITOTS LANDNADRAISO 45614002:9)E( 1 Textiles Unevenness of textile strands Capacitance method 1Scope This Internation
24、al Standard describes a method, using capacitance measuring equipment, for determining the unevenness of linear density along the length of textile strands. The method is applicable to tops, slivers, rovings, spun yarns and continuous filament yarns, made from either natural or man-made fibres, in t
25、he range of 4 tex () to 80 ktex () for staple-fibre strands and 1 tex () to 600 tex () for continuous-filament yarns. It is not applicable to fancy yarns or to strands composed fully or partly of conductive materials such as metals; the latter require an optical sensor (see A.4). The method describe
26、s the preparation of a variance-length curve, as well as the determination of periodicities of linear density. It covers also the counting of imperfections in the yarn, namely of neps and of thick and thin places. Irregularities in the distribution of additives such as sizes, in moisture content and
27、 in fibre blending may increase the measured unevenness above its true value. 2Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the refer
28、enced document (including any amendments) applies. ISO 139, Textiles Standard atmospheres for conditioning and testing 3Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 unevenness variation of linear density along the length of a continuous stra
29、nd or yarn NOTEThe term is also used occasionally for the variation of yarn diameter. 3.2 coefficient-of-variation unevenness value of unevenness (3.1) expressed as a coefficient of variation NOTE 1The coefficient-of-variation unevenness is expressed in percent, for example . NOTE 2See also 4.5 and
30、4.6. 3.3 mean-deviation unevenness value of unevenness (3.1) expressed as an average mean deviation NOTE 1The mean-deviation unevenness is expressed in percent, for example, . g/kmkg/km g/kmg/km CVu CVu=18,3 % Uu Uu=14,6 % BS ISO 16549:2004 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 02:0
31、4:49 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 2 NOTE 2See also 4.5 and 4.6. 3.4 capacitor length effective length of the capacitor in the direction of the specimen movement, usually to 3.5 length between length of the test specimen for which the instrument takes an individual reading of mass NOTE
32、1The unevenness value decreases as is increased. NOTE 2In the capacitance method, is normally the capacitor length but it can be increased electronically. NOTE 3 is sometimes referred to in the literature as . 3.6 length within length of the specimen for which an individual value of unevenness is de
33、termined and a reading is given NOTE 1The unevenness value increases as is increased. When is more than or so, then a further lengthening of increases (or ) only slightly. NOTE 2 is sometimes referred to in the literature as . 3.7 total measured length sum of all measured lengths 3.8 nep tightly tan
34、gled knot-like mass of unorganized fibres 3.9 package yarn wound to a shape, which may be supported (for example, bobbins, cones) or unsupported (for example, skeins, cakes), suitable for conditioning and testing 3.10 spectrogram attachment to unevenness testers for the calculation and presentation
35、of periodic variations in the strand 3.11 thick place yarn defect with linear density substantially (at least ) greater than that of the adjoining segments of the yarn and extending for at least 3.12 thin place yarn defect with linear density substantially (at least ) smaller than that of the adjoin
36、ing segments of the yarn and extending for at least 4Principle 4.1A specimen is passed between two plates of a capacitor causing changes in capacitance which are proportional to the changes of mass of the specimen. The instrument evaluates these changes and reports them as or . 8 mm20 mm Lb Lb Lb Lb
37、B Lw LwLw100 m LwCVuUu LwW Lw 50 % 5 mm 50 % 5 mm CVuUu BS ISO 16549:2004 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 02:04:49 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 3 4.2The fibre dielectric constant is also a factor determining the capacitance change. As long as the dielectric const
38、ant is unchanging (non-blended strands or perfectly uniform blending), the dielectric constant has no influence on the unevenness reading, which depends solely on the variation of mass. If the dielectric constant differs for the types of fibres in a blend and if, at the same time, the blend is irreg
39、ular, then the reading of unevenness is increased above its true value. The interpretation of results therefore requires caution. 4.3Several studies have been conducted over the years, see Reference 3 for example, comparing the true unevenness of a specimen, determined by cutting and weighing (see A
40、.3.1), with the reading from an unevenness tester. Good agreement was obtained, so the readings from the tester can be taken as being the true unevenness value. 4.4The value of unevenness has meaning only if both and are known and they should, in principle, always be reported, preferably as (, ). EX
41、AMPLE (, ). In practice, these two values are usually left unstated and are assumed to be those of the most commonly used unevenness tester, namely : for yarns, for rovings, for slivers and tops; : total length of yarn on the package. 4.5There are two possible expressions for unevenness, and . The i
42、s now obsolete and its use, while permitted, is discouraged. is the preferred expression. 4.6If mass is distributed near to “normal”, then the ratio of is approximately 1,25. This conversion factor must be used cautiously because, in case of departures from normality, the ratio can be considerably d
43、ifferent. The conversion factor may be used to convert a table of quality levels from to . 4.7When is plotted against , a “variance-length curve” is obtained which gives additional information on the materials unevenness. When the plot is made on log-log paper, then the curve is almost a straight li
44、ne and its slope gives information on the relationship between short-term and long-term unevenness. 4.8Unevenness testers usually contain a spectrogram, which analyses the data and provides information on periodic variations of linear density. This information is useful in finding faults in the proc
45、essing. The analysis uses an algorithm based on the Fourier transformation. 4.9Unevenness testers usually contain a counter for yarn imperfections, namely neps, and thick and thin places. The level beyond which the imperfections are counted can be adjusted. 4.10Unevenness is a fundamental feature of
46、 yarn construction. It influences the efficiency of processing as well as fabric appearance. Lower unevenness generally results in a better-looking fabric but the relation is not simple and interpretation requires special care. 5Apparatus 5.1Different types of apparatus are in use for measuring stra
47、nds made of staple fibres and filament yarns. 5.2The apparatus consists of the following elements: a)measuring device, featuring several measuring condensers, usually grouped into one unit, for strands of varying linear density, yarn guiding and pretensioning devices, an adjustable-speed motor to ad
48、vance the strand; LbLw CVuLbLw CVu10 mm 1 000 m Lb8 mm12 mm20 mm Lw CVuUuUu CVu CVu/Uu UuCVu CVuLb BS ISO 16549:2004 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 02:04:49 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 4 b)signal processing unit, which computes and indicates the values of or an
49、d may also calculate the variance-length curve and present a graph of the periodic variations of linear density, also counts the number of imperfections in most instruments. The unit shall be able to operate at the threshold level of , above which thick places are counted, and the level of , below which thin places are counted. reports a reading for neps which shall be a product of the length, expressed in millimetres, of the nep and the percent excess over the aver
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