1、Designation: D 3882 99 (Reapproved 2006)Standard Test Method forBow and Skew in Woven and Knitted Fabrics1This standard is issued under the fixed designation D 3882; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of bow andskew of filling yarns in woven fabrics and the courses inknitted fabri
3、cs.1.2 This test method can also be used to measure the bowand skew of printed geometric designs such as plaids.1.3 The values stated in either SI units or inch-pound unitsare to be regarded separately as the standard. Within the text,the inch-pound units are shown in parentheses. The valuesstated i
4、n each system may not be exact equivalents; therefore,each system shall be used independently of the other. Combin-ing values from the two systems may result in nonconformancewith this test method.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its us
5、e. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 123 Terminology Relating to TextilesD 1776 Practice for Conditioning and
6、Testing TextilesD 2904 Practice for Interlaboratory Testing of a Textile TestMethod that Produces Normally Distributed DataD 2906 Practice for Statements on Precision and Bias forTextilesD 3990 Terminology Relating to Fabric Defects3. Terminology3.1 Definitions:3.1.1 bow, na fabric condition resulti
7、ng when filling yarnsor knitting courses are displaced from a line perpendicular tothe selvages and form one or more arcs across the width of thefabric. (See alsodouble bow .)3.1.2 double bow, ntwo fabric bows, arcing in the samedirection, as in a flattened M or W depending on the viewingangle. (See
8、 alsodouble bow .) (Compare double reverse bow.)3.1.2.1 DiscussionIn tubular knits, there may be differen-tial bowing between the top and bottom of the tube.3.1.3 double hooked bow, none hooked bow at each sideof the fabric that arc in opposite directions. (See alsohookedbow .)3.1.4 double reverse b
9、ow, ntwo fabric bows arcing inopposite directions. (See also bowdouble bow.) (Compare .)3.1.5 hooked bow, na fabric condition in which the fillingyarns or knitted courses are in the proper position for most ofthe fabric width but are pulled out of alignment at one side ofthe fabric. (See also double
10、 hooked bow.)3.1.6 knitted fabric, na structure produced by interloopingone or more ends of yarn or comparable materials.3.1.7 skew, na fabric condition resulting when fillingyarns or knitted courses are angularly displaced from a lineperpendicular to the edge or side of the fabric.3.1.7.1 Discussio
11、nKnitted courses or filling yarns usuallyappear as straight line at right angles to the edge or side of thefabric. When tubular knitted fabric is finished, differential skewmay occur on the top and bottom part of the tube.3.1.8 standard atmosphere for testing textiles,nlaboratory conditions for test
12、ing fibers, yarns, and fabrics inwhich air temperature and relative humidity are maintained atspecific levels with established tolerances.3.1.8.1 DiscussionTextile materials are used in a numberof specific end-use applications that frequently require differenttesting temperatures and relative humidi
13、ties. Specific condi-tioning and testing of textiles for end-product requirements canbe carried out using Table 1 in Practice D 1776.3.1.9 For definitions of fabric defect terms, refer to Termi-nology D 3990. For definitions of other textile terms used inthis test method, refer to Terminology D 123.
14、4. Summary of Test Method4.1 BowA straightedge is placed across the fabric be-tween two points at which a marked filling yarn, knittingcourse, designated printed line, or designated design meets the1This test method is under the jurisdiction of ASTM Committee D13 on Textilesand is the direct respons
15、ibility of Subcommittee D13.60 on Fabrics, Specific.Current edition approved Jan. 1, 2006. Published February 2006. Originallyapproved in 1980. Last previous edition approved in 1999 as D 3882 99.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at
16、 serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.two selvages or edges. The greatest distance betwe
17、en thestraightedge and the marked filling line, knitting course,designated printed line, or designated design is measuredparallel to the selvage.4.2 SkewThe straight-line distortion of a marked fillingyarn, knitting course, designated printed line, or designateddesign is measured from its normal per
18、pendicular to theselvage or edge.5. Significance and Use5.1 This test method is considered satisfactory for accep-tance testing of commercial shipments.5.1.1 If there are differences of practical significance be-tween reported test results for two laboratories (or more),comparative tests should be p
19、erformed to determine if there isa statistical bias between them, using competent statisticalassistance. As a minimum, the test samples to be used are ashomogeneous as possible, are drawn from the material fromwhich the disparate test results were obtained, and are ran-domly assigned in equal number
20、s to each laboratory for testing.Other fabrics with established test values may be used for thispurpose. The test results from the two laboratories should becompared using a statistical test for unpaired data, at aprobability level chosen prior to the testing series. If a bias isfound, either its ca
21、use must be found and corrected, or futuretest results must be adjusted in consideration of the knownbias.5.2 Individual rolls are normally accepted or rejected on thebasis of the maximum amount of bow or skew in a specific rollof fabric. The average bow or skew in a roll or lot or the rangeof bow o
22、r skew in a roll may be determined but are notnormally used in the trade for acceptance or rejection.5.3 Bow or skew can be induced during fabric manufactur-ing, dyeing, tentering, finishing, or other operations where apotential exists for uneven distribution of tensions across thefabric width. Bow
23、and skew are more visually displeasing incolored, patterned fabrics such as plaids and horizontal stripesrather than in solid colors because the contrast makes thedistortion more prominent. These defects may cause sewingproblems in such fabrics and draping problems in finishedproducts. In some cases
24、, a specified amount of skew is needed,for example, to prevent trouser leg twisting. Matching plaidsfrom distorted patterns may create serious problems for thegarment manufacturer or home sewer. Wavy or sharp breaks inthe bow line are more detrimental to the appearance of smallparts of a garment (su
25、ch as collars, pockets, and so forth) thana gradual slope from a straight line.6. Apparatus6.1 Measuring Stick or Steel Tape, graduated in 1-mm(116-in.) divisions and longer than the width of the fabric thatis to be measured.6.2 Rigid Straightedge, longer than the width of the fabricthat is to be me
26、asured.6.3 Flat Surface, of sufficient length to unroll or unfold thefabric (see 6.4).6.4 Fabric Inspection Table (Optional), to unroll and rollfabric rolls or unfold and fold fabric bolts with sufficientlighting that provides transmitted light from underneath thefabric to make the defect more clear
27、ly visible.7. Sampling and Test Specimens7.1 Primary Sampling UnitConsider rolls or bolts offabric or fabric components of fabricated systems to be theprimary sampling unit, as applicable.7.2 Laboratory Sampling UnitAs a laboratory samplingunit take the entire roll or bolt after removing a first 1-m
28、m(1-yd) length. For fabric components of fabricated systems, usethe entire system.7.3 Test SpecimensAs test specimens, select 3 test areasfrom each laboratory sampling unit. Exclude the first and lastfifth of the roll or bolt or piece length. Select test areas atrandom but no closer to one another t
29、han one fifth of the rollor bolt or piece length.8. Conditioning8.1 Condition the test specimens to moisture equilibrium fortesting in the standard atmosphere for testing textiles inaccordance with Practice D 1776 or, if applicable, in thespecified atmosphere in which the testing is to be performed.
30、8.1.1 When full rolls or bolts of fabric cannot be properlyconditioned in a reasonable time with available facilities,perform the test without conditioning and report the actualcondition prevailing at the time of the test. Such results maynot correspond with the results obtained when testing condi-t
31、ioned specimens at the standard atmosphere for testing tex-tiles.9. Procedure9.1 Test the test specimens in the standard atmosphere fortesting textiles in accordance with Section 8.9.2 Handle the test specimens carefully to avoid altering thenatural state of the material.9.3 Lay the fabric on a smoo
32、th, horizontal surface withouttension in any direction or use the optional fabric inspectiontable.9.4 Bow:9.4.1 Measure the bow in three places spaced as widely aspossible along the length of the fabric or along a minimum ofTABLE 1 Critical Differences, 95 % Probability Level, for Bowand Skew for th
33、e Conditions NotedProperty Number ofObservations inEach AverageCritical Differences for the Conditions NotedA,%Repeatability Reproducibility(Single-Operator)Precision(Within-Laboratory)Precision(Between-Laboratory)PrecisionBow 1 0.80 0.80 0.803 0.46 0.46 0.466 0.33 0.33 0.3312 0.23 0.23 0.2324 0.16
34、0.16 0.16Skew 1 2.99 2.99 3.183 1.73 1.73 2.046 1.22 1.22 1.6312 0.86 0.86 1.3824 0.61 0.61 1.24AThe critical differences for Table 1 were calculated using t = 1.960, which isbased on infinite degrees of freedom.D 3882 99 (2006)21 m (1 yd). If possible, make no measurement closer to theends of the r
35、oll or piece of fabric than 1 m.9.4.2 If evident, follow a distinctive color yarn or patternline across the width of the fabric. Otherwise, trace one fillingyarn, knitting course, or printed line across the full width of thefabric using a soft pencil or suitable marker.9.4.3 Place a rigid straighted
36、ge across the fabric connectingthe points at which the distinctive color yarn or pattern line, ormarked yarn meets the two selvages or edges.9.4.4 Measure the distance along the straightedge betweenthe two selvages or edges to the nearest 1 mm (116 in.) andrecord as the baseline distance (BL).9.4.4.
37、1 For certain end uses where several narrow panels aresewn in a garment, it will be necessary to measure the bowacross a narrower distance than the total width of the fabric, forexample, a width of 38 cm (15 in.). This distance is used as thefabric width when calculating the bow.9.4.5 Measure the gr
38、eatest distance parallel to the selvagesor edges between the straightedge and the distinctive color yarnor pattern line, or marked yarn to the nearest 1 mm (116 in.) andrecord as the bow distance (D) including the type. (See Fig. 1).9.4.5.1 If double bow is evident, measure and record bothdistances.
39、NOTE 1Fig. 1 represents typical examples of bows in a fabric that donot have any skew. Many variations in the shape or deepest portion of thearc can occur in actual fabrics. No provision is made to measure bow inthe presence of skew.9.5 Skew:9.5.1 Measure the skew in three places spaced as widely as
40、possible along the length of the fabric or along a minimum of1 m (1 yd). If possible, make no measurement closer to theends of the roll or piece of fabric than 1 m.9.5.2 If evident, follow a distinctive color yarn or patternline across the width of the fabric. Otherwise, trace one fillingyarn, knitt
41、ing course, or printed line across the full width of thefabric using a soft pencil or suitable marker (Line AC ifright-hand skew, Line AD if left-hand skew).9.5.3 Place a rigid straightedge across the fabric widthperpendicular to the selvage or edge such that it coincides withthe lower point on the
42、fabric at which the distinctive color yarnor pattern line, or marked yarn meets one of the selvages oredges (Line BC).9.5.4 Measure the distance along the straightedge betweenthe two selvages or edges (Line BC) to the nearest 1 mm (116in.) and record as the fabric width (W). (See Fig. 2.)9.5.5 Measu
43、re the distance parallel to the selvages or edgesbetween the straightedge and the distinctive color yarn orpattern line, or marked yarn to the nearest 1 mm (116 in.) (LineAD, or BD) and record including the skew direction, right-hand“ Z,” left hand “S,” and whether evident on the face orback of the
44、fabric. (See Fig. 2.)NOTE 2Fig. 2 represents a schematic drawing of typical skew;variations may occur in actual fabric. Examination of Fig. 2 will show thatthe skew in a fabric will be consistently categorized as left-hand (orright-hand) regardless whether the fabric is being fed from the top orbott
45、om roll of the viewing frame or whether the direction of skew ismeasured from the right or left selvage or side, provided either the face orback of the fabric is being viewed.10. Calculation10.1 Bow, Individual MeasurementsCalculate the maxi-mum bow of individual specimens to the nearest 0.1 % using
46、Eq 1.Bow, % 5 100D/BL! (1)where:D = maximum bow distance, mm (in.), (from 9.4.5), andBL = baseline distance, mm (in.), (from 9.4.4).10.1.1 If double bow is present, calculate the larger of thetwo bows.10.2 Skew, Individual MeasurementsCalculate the skewof individual specimens to the nearest 0.1 % us
47、ing Eq 2 or Eq3, as applicable.Skew, %, right2hand 5 100AB!/BC (2)Skew, %, left2hand 5 100BD!/BC (3)where:AB = skew distance, right hand, mm (in.), (from 9.5.5),BD = skew distance, left hand, mm (in.), (from 9.5.5), andBC = width of fabric, mm (in.), (from 9.5.4).11. Report11.1 Report that the skew
48、or bow were determined asdirected in Test Method D 3882. Describe the material orproduct sampled and the method of sampling used.11.2 Report the following information for each laboratorysampling unit:11.2.1 Bow:11.2.1.1 Individual bow in units of measurements andpercent,11.2.1.2 Maximum bow in units
49、 of measurements andpercent,11.2.1.3 Fabric width, and11.2.1.4 Type of bow observed, for example, double bow,double reverse bow, double hooked bow, hooked bow, or othervariation.11.2.2 Skew:FIG. 1 Typical Bow ConditionsD 3882 99 (2006)311.2.2.1 Individual skew in units of measurements andpercent,11.2.2.2 Maximum skew in units of measurements andpercent,11.2.2.3 Fabric width,11.2.2.4 Direction of skew, right-hand “Z,” left-hand “S”,and11.2.2.5 Side of fabric where skew was observed, face orback.12. Precision and Bias12.1 SummaryIn comparing two averages
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