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1、INTERNATIONAL STANDARD ISO 16549 First edition 2004-06-01 Reference number ISO 16549:2004(E) ISO 2004 Textiles Unevenness of textile strands Capacitance method Textiles Irrgularit des fils textiles Mthode capacitive Copyright International Organization for Standardization Provided by IHS under licen
2、se with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 03:46:17 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 16549:2004(E) ii ISO 2004 All rights reserved PDF disclaimer This PDF file may contain embedded typefaces. In accordance with A
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5、are has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. ISO 2004 All rights reserved. Unless otherwise specified, no part of this publication m
6、ay be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel
7、. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 03:46:17 MDTNo reproduc
8、tion or networking permitted without license from IHS -,-,- ISO 16549:2004(E) ISO 2004 All rights reserved iii Contents 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 a
9、nd expression of results . 6 10Test report 6 Annex A (informative) Other methods for the determination of unevenness . 8 Bibliography . 10 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04
10、/20/2007 03:46:17 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 16549:2004(E) iv ISO 2004 All rights reserved Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of prep
11、aring 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-governmental, in
12、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 task
13、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. Attention
14、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. This I
15、nternational Standard cancels and replaces ISO 2649 which is now obsolete. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 03:46:17 MDTNo reproduction or networking permitted wit
16、hout license from IHS -,-,- ISO 16549:2004(E) ISO 2004 All rights reserved v Introduction In the 1960s the International Wool Textile Organization (IWTO) prepared an unevenness method destined for yarns and other strands made of wool. The method was adopted by ISO as ISO 2649:1974. It contains a dis
17、cussion 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-2000 when the present International Standard was written. Later, the IWTO prepared a new method, IWTO-18-00, published in 2000. IS
18、O 16549 has mostly new wording but includes some elements of ISO 2649 and of IWTO-18-00 with thanks to IWTO. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 03:46:17 MDTNo reprod
19、uction or networking permitted without license from IHS -,-,- . vi Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 03:46:17 MDTNo reproduction or networking permitted without lic
20、ense from IHS -,-,- INTERNATIONAL STANDARDISO 16549:2004(E) ISO 2004 All rights reserved 1 Textiles Unevenness of textile strands Capacitance method 1Scope This International Standard describes a method, using capacitance measuring equipment, for determining the unevenness of linear density along th
21、e 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 the range of 4 tex () to 80 ktex () for staple-fibre strands and 1 tex () to 600 tex () for continuous-filament yarns. It is not
22、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 describes the preparation of a variance-length curve, as well as the determination of periodicities of linear density. It covers also th
23、e 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 in fibre blending may increase the measured unevenness above its true value. 2Normative references The following referenced doc
24、uments are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 139, Textiles Standard atmospheres for conditioning and testing 3Terms an
25、d 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 strand or yarn NOTEThe term is also used occasionally for the variation of yarn diameter. 3.2 coefficient-of-variation unevenness va
26、lue 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 4.6. 3.3 mean-deviation unevenness value of unevenness (3.1) expressed as an average mean deviation NOTE 1The mean-deviation une
27、venness is expressed in percent, for example, . g/kmkg/km g/kmg/km CVu CVu=18,3 % Uu Uu=14,6 % Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 03:46:17 MDTNo reproduction or netw
28、orking permitted without license from IHS -,-,- ISO 16549:2004(E) 2 ISO 2004 All rights reserved 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 instr
29、ument takes an individual reading of mass NOTE 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 fo
30、r which an individual value of unevenness is determined 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
31、sum of all measured lengths 3.8 nep tightly tangled 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 unevennes
32、s testers for the calculation and presentation 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 substantia
33、lly (at least ) smaller than that of the adjoining 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
34、 and reports them as or . 8 mm20 mm Lb Lb Lb LbB Lw LwLw100 m LwCVuUu LwW Lw 50 % 5 mm 50 % 5 mm CVuUu Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 03:46:17 MDTNo reproduction
35、 or networking permitted without license from IHS -,-,- ISO 16549:2004(E) ISO 2004 All rights reserved 3 4.2The fibre dielectric constant is also a factor determining the capacitance change. As long as the dielectric constant is unchanging (non-blended strands or perfectly uniform blending), the die
36、lectric 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 irregular, then the reading of unevenness is increased above its true value. The in
37、terpretation 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.3.1), with the reading from an unevenness tester. Good agreement was obtained
38、, 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 (, ). EXAMPLE (, ). In practice, these two values are usually left unstated and are as
39、sumed 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 is now obsolete and its use, while permitted, is discouraged. is the preferred
40、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 different. The conversion factor may be used to convert a table of quality leve
41、ls 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 line and its slope gives information on the relationship between short-term and
42、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 processing. The analysis uses an algorithm based on the Fourier transformation. 4.
43、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 yarn construction. It influences the efficiency of processing as well as fabr
44、ic 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 strands made of staple fibres and filament yarns. 5.2The apparatus consists of the
45、 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 advance the strand; LbLw CVuLbLw CVu10 mm 1 000 m Lb8 mm12 mm20 mm Lw CVuUuUu CV
46、u CVu/Uu UuCVu CVuLb Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 03:46:17 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 16549:2004(E) 4 ISO 20
47、04 All rights reserved b)signal processing unit, which computes and indicates the values of or and 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 ope
48、rate 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 average linear density of the yarn (for example, ). The level of , above which neps are counted, shall be available. other levels (for the three imperfection t