ASTM_D_4846_-_96_2011.pdf

Designation:D484696(Reapproved 2011)Standard Test Method forResistance to Unsnapping of Snap Fasteners1This standard is issued under the fixed designation D4846;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()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the determination of the forcerequired to disengage snap fasteners by a pull perpendicular toand parallel with the plane of the snap fastener.1.2 This test method requires attachment of snaps to speci-mens using specifications provided by the producers of thesnaps.1.3 This test method is used to establish correlation to wearconditions and for comparing different brands and types ofsnap fasteners.1.4 The values stated in SI units are to be regarded as thestandard.The values stated in the parentheses are for informa-tion only.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 and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D76 Specification for Tensile Testing Machines for TextilesD123 Terminology Relating to TextilesD1776 Practice for Conditioning and Testing Textiles3.Definitions3.1 lateral holding strength,nthe force required to disen-gage a snap fastener resulting from a pull in the plane parallelto the material to which the snap fastener is attached.3.2 snap action,nthe force required to disengage a snapfastener resulting from a pull exerted perpendicular to the planeof material to which the snap fastener is attached.3.3 snap fastener,na device for attaching one material toanother consisting of matching male and female parts,each ofwhich is attached to a separate material so that the parts can bejoined by a low compressive force and separated by a lowperpendicular tensile force.3.4 For definitions of other textile terms used in this testmethod,refer to Terminology D123.4.Summary of Test Method4.1 Snap fasteners mounted on strips of material near theend are tested on standard tensile testing machines equippedfor testing the strength of textile fabrics and having sensitivityfor accurate low force levels.4.2 Tests are made on snap fasteners before laundering withthe option of testing again after a pre-determined number oflaunderings or other types of refurbishing.5.Significance and Use5.1 This test method may be used for acceptance testing ofcommercial shipments of snap fasteners,but caution is advisedsince information on between laboratory precision is incom-plete.Comparative tests as directed in 5.1.1 are advisable.5.1.1 In case of a dispute arising from differences inreported test results when using Test Method D4846 foracceptance testing of commercial shipments,the purchaser andseller should conduct comparative tests to determine if there isstatistical bias between their laboratories.Competent statisticalassistance is recommended for the investigation of bias.As aminimum,the two parties should take a group of test speci-mens that are as homogeneous as possible and that are from alot of material of the type in question.The test specimens thenshould be assigned randomly in equal numbers to eachlaboratory for testing.The average results from the twolaboratories should be compared using Students t-test forunpaired data and an acceptable probability level chosen by thetwo parties before testing is begun.If a bias is found,either itscause must be found and corrected or the purchaser and sellermust agree to interpret future test results in the light of theknown bias.6.Apparatus6.1 Tensile Testing MachineA constant rate of extension(CRE)type or constant rate of traverse(CRT)type testing1This test method is under the jurisdiction ofASTM Committee D13 on Textilesand is the direct responsibility of Subcommittee D13.54 on Subassemblies.Current edition approved Jan.1,2011.Published March 2011.Originallyapproved in 1988 as D4846 88.Last previous edition approved in 2004 asD4846 96(2004).DOI:10.1520/D4846-96R11.2For referenced ASTM standards,visist the ASTM wbsite,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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 machine conforming to Specification D76 with a rate oftraverse of 305 mm(12 in.)/min,or a rate agreed upon betweenpurchaser and seller,and a scale which will produce accurateresults at very low force levels.There may be no overallcorrelation between the results obtained with the CRE and CRTtensile testing machines.In the case of controversy,however,the CRE method shall preva