1、Designation:D1425/D1425M14(Reapproved 2020)Standard Test Method forEvenness of Textile Strands Using Capacitance TestingEquipment1This standard is issued under the fixed designation D1425/D1425M;the number immediately following the designation indicates theyear of original adoption or,in the case of
2、 revision,the year of last revision.A number in parentheses indicates the year of lastreapproval.A superscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the indirect measurement ofevenness(mass variation)of non-conductive textile
3、strands,including top,comber lap,sliver,roving,and yarn producedfrom staple fibers and continuous filament yarns,by means ofcapacitance testing equipment.1.2 Strands made from fiber blends can be tested using thistest method only if the different fibers are uniformly distributedthroughout the strand
4、.1.3 The test method provides numeric values for the mea-surement and evaluation of short-,mid-,and long-term massvariations of the tested strand in terms of frequently occurringfaults classified as thin places,thick places,and neps andgraphical representations of evenness values in the form ofdiagr
5、am charts,spectrograms,length variation curves,andhistograms.1.4 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard.The values stated ineach system may not be exact equivalents;therefore,eachsystem shall be used independently of the other.Combiningvalue
6、s from the two systems may result in non-conformancewith the 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-priate safety,health,and environmental practices and de
7、ter-mine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-menda
8、tions issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D123 Terminology Relating to TextilesD1776 Practice for Conditioning and Testing TextilesD2258 Practice for Sampling Yarn for TestingD4849 Terminology Related to Yarns and
9、FibersE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 Definitions:3.1.1 The following terms are relevant to this standard:electric constant;evenness;imperfections
10、;length between,Lb;length capacitance zone,Lc;mass variation;mean deviation ofevenness,U%;sample length Ls;strand;strand irregularity;and total imperfections.3.1.2 For definitions of other textile terms used in this testmethod,refer to Terminology D123 and Terminology D4849.4.Basic Principles of Tes
11、t Method4.1 Properties of strand irregularity measured along itslength are measured in terms of mass variation.4.2 The direct method of evenness testing utilizes thetechnique of cutting and weighing strand segments of length Lband is the reference method of determining evenness(massvariation).Utiliz
12、ation of the capacitance measurement tech-nique is an indirect testing method.The accuracy of an indirectmethod of testing can be judged by a comparison of evennessvalues between it and the direct method(cutting and weigh-ing).4.3 In capacitance testing,a high frequency electric field isgenerated in
13、 the space between a pair of capacitor plates(measuring slots).If the mass of a strand moving between theplates changes,the electrical field between the plates changes1This test method is under the jurisdiction ofASTM Committee D13 on Textilesand is the direct responsibility of Subcommittee D13.58 o
14、n Yarns and Fibers.Current edition approved Feb.1,2020.Published February 2020.Originallyapproved in 1956.Last previous edition approved in 2014 as D1425/D1425M-14.DOI:10.1520/D1425_D1425M-14R20.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at ser
15、viceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with in
16、ternationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.accordingly,and results in electrical signal output variationproportional to the mass variation of the strand.4.4 Evenness is always expressed as variation betweensuccessive lengths L and over a total length Ls.When the Lcevenness is measured,it cor