ASTM_D_6242_-_98_2004.pdf

Designation:D 6242 98(Reapproved 2004)Standard Test Method forMass Unit Area of Nonwoven Fabrics1This standard is issued under the fixed designation D 6242;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last 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 mass/unitarea of all nonwoven fabrics.1.2 The values stated in SI units or inch-pound units shall beregarded separately as the standard.The values stated in eachsystem may not be exact equivalents;therefore,each systemmust be used independently of the other,without combiningvalues in any way.1.3 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 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 Textiles for TestingE 177 Practice for Use of the Terms Precisions and Bias inASTM Test MethodsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 Definitions:For definitions of other textile terms used inthis test method,refer to Terminology D 123.3.2 Definitions of Terms Specific to This Standard:3.2.1 nonwoven fabric,na textile structure produced bybonding or interlocking of fibers,or both,accomplished bymechanical,chemical,thermal,or solvent means or by acombination thereof.4.Summary of Test Method4.1 A specimen of specified area is weighed and themass/unit area calculated.5.Significance and Use5.1 This test method determines the ratio of mass/unit areaof any nonwoven fabric.Many properties of nonwovens,including strength,thickness,porosity,tearing strength,andothers are influenced by changes in mass/unit area.For thisreason,many nonwovens specifications include targets andlimits for this property,which may be verified using thisprocedure.Also,it is a useful procedure to use in controllingproduction of nonwovens and verifying the property of thematerial being delivered to the customer.5.2 The procedure in this test method may be used foracceptance testing of commercial shipments,but caution isadvised since information about between-laboratory precisionis incomplete.Comparative tests in accordance with 5.2.1 areadvisable.5.2.1 In case of a dispute arising from differences inreported test results when using the procedures in this testmethod for acceptance testing of commercial shipments,thepurchaser and the manufacturer should conduct comparativetests to determine if there is a statistical bias between theirlaboratories.Competent statistical assistance is recommendedfor the investigation of bias.As a minimum,the two partiesshould take a group of test specimens that are as homogeneousas possible and which are from a lot of material of the type inquestion.The test specimen then should be randomly assignedin equal numbers to each laboratory for testing.The averageresults from the two laboratories should be compared using theappropriate Students t-test and an acceptable probability levelchosen by the two parties before testing is begun.If a bias isfound,either its cause must be found and corrected or thepurchaser and the manufacturer must agree to interpret futuretest results with consideration to the known bias.6.Apparatus6.1 Balance,having a weighing accuracy of 6 0.0002 g.6.2 Steel Rule,at least 30 cm(12 in.)in length,withsubdivisions of 0.5 mm(0.02 in.).NOTE1The use of cutting dies of known dimensions is recommendedfor cutting the test specimens required in 7.3.1This test method is under the jurisdiction ofASTM Committee D 13 on Textilesand is the direct responsibility of Subcommittee D13.64 on Non-Woven FabricCurrent edition approved April 10,1998.Published September 1998.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandardsvolume 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.7.Sampling7.1 Lot SampleAs a lot sample for acceptance testing,take at random the number of rolls,or pieces,of nonwovenfabric directed in an applicable material specification or otheragreement between the purchaser and the supplies.Considerthe rolls,or pieces,of nonwoven fabric to be the primarysampling units.In the absence of such an agreement,take thenumber of nonwoven fabric rolls specified in Table 1.NOTE2An adequate specification or other agreement between thepurchaser and supplier requires taking into account the variability betweenrolls or pieces of fabric and b