1、Designation: D 4846 96 (Reapproved 2004)Standard Test Method forResistance to Unsnapping of Snap Fasteners1This standard is issued under the fixed designation D 4846; 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 the forcerequired to disengage snap fasteners by a pull perpendicular toand
3、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 fastener
4、s.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 esta
5、blish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 76 Specification for Tensile Testing Machines for TextilesD 123 Terminology Relating to TextilesD 1776 Practice for Conditioning Textile
6、s for Testing3. 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
7、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 s
8、eparated by a lowperpendicular tensile force.3.4 For definitions of other textile terms used in this testmethod, refer to Terminology D 123.4. Summary of Test Method4.1 Snap fasteners mounted on strips of material near theend are tested on standard tensile testing machines equippedfor testing the st
9、rength 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
10、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
11、 D 4846 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
12、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
13、 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
14、Testing MachineA constant rate of extension(CRE) type or constant rate of traverse (CRT) type testingmachine conforming to Specification D 76 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 f
15、orce levels. There may be no overall1This test method is under the jurisdiction of ASTM Committee D13 on Textilesand is the direct responsibility of Subcommittee D13.54 on Subassemblies.Current edition approved Sept. 10, 1996. Published November 1996. Originallypublished as D 4846 88.2For referenced
16、 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Consh
17、ohocken, PA 19428-2959, United States.correlation between the results obtained with the CRE and CRTtensile testing machines. In the case of controversy, however,the CRE method shall prevail.6.2 JawsThe back jaws of the clamps on the tensiletesting machine should be at least the same width as the fro
18、ntjaws. The front jaws must be 25.4 mm (1 in.) wide.6.3 Aluminum PlateA plate is required measuring 50 by100by4mm(2by4by18 in.) with dowel pins inserted (seeFig. 1).6.4 Attaching MachineA hand operated, foot operated, orautomatic machine for attaching snap fastener parts conform-ing to specification
19、s of seller.7. Sampling7.1 Lot SampleAs a lot sample for acceptance testing,take at random the number of shipping cartons of snapfasteners or shipping cartons of garments directed in anapplicable material specification or other agreement betweenthe purchaser and the seller. Consider shipping cartons
20、 of snapfasteners or shipping cartons of garments to be the primarysampling units.NOTE 1An adequate specification or other agreement between thepurchaser and the seller requires taking into account the variabilitybetween shipping cartons, units within a shipping carton, and betweenspecimens from a u
21、nit within a shipping carton, to provide a sampling planwith a meaningful producers risk, consumers risk, acceptable qualitylevel, and limiting quality level.7.2 Laboratory SampleAs a laboratory sample for accep-tance testing, proceed as follows:7.2.1 Unattached Snap FastenersTake one box or card of
22、unattached snap fasteners at random from each shipping cartonin the lot sample. If the male and female parts are packedseparately, take one box of each from each shipping carton inthe lot sample.7.2.2 Attached Snap FastenersTake one garment fromeach shipping carton in the lot sample.7.3 Test Specime
23、ns:7.3.1 Unattached Snap FastenersFrom each box or cardin the laboratory sample, take five snap fasteners at random. Ifthe male and female parts are packed separately, for each pairof boxes from a shipping carton in the lot sample, take fivemale parts at random and match them with five female partst
24、aken at random.7.3.2 Attached Snap FastenersFrom each garment in thelaboratory sample, take five snap fasteners at random ongarments with more than five. If less than five, take all snapfasteners from each garment.8. Conditioning8.1 Condition the specimens by bringing them from the dryside to approx
25、imate moisture equilibrium for testing in thestandard atmosphere for testing textiles as directed in PracticeD 1776.9. Procedure9.1 Preparing Specimens:9.1.1 Attaching Loose Snap FastenersWhen snap fasten-ers are to be attached to a material typical to intendedproduction, the pinch setting and other
26、 conditions specified bythe seller must be used. Cut fabric specimens to dimensions of38 by 89 mm (1.5 by 3.5 in.) and attach male part to one fabricspecimen and female part to the other fabric specimen, bothapproximately 19 mm (34 in.) from the ends or edge of thefabric specimens (see Fig. 2).9.1.2
27、 Cutting Specimens From GarmentsCut specimenfrom garments so that the snap fasteners are approximately 19mm (34 in.) from the end of a specimen measuring 38 by 89mm (1.5 by 3.5 in.). Cut the specimen as close to thesedimensions as possible where snap fastener spacings limitspecimen size cut from gar
28、ments.9.1.3 Marking of SpecimensSnap the fastener parts to-gether, keeping the edges of the two pieces of material inalignment. From the center of the snap fastener measure 38mm (1.5 in.) in each direction and place marks across the twopieces of material to provide a 76 mm (3 in.) overall length and
29、visual reference.9.2 Determination of Snap ActionSet the distance be-tween the upper and lower clamps of the testing machine for 76FIG. 1 Aluminum Plate FIG. 2 Specimen and Snap Fastener Arrangement for TestingD 4846 96 (2004)2mm (3 in.). Clamp the aluminum plate loosely in the jaw of theupper clamp
30、 to prevent the specimen from twisting. Insert thefemale end of the specimen so that the lower edge of the jawin the upper clamp is even with the mark placed on the materialand tighten the clamp. Clamp the male end of the specimen inthe jaw of the lower clamp so that the two snapped halves arestraig
31、ht and the pull is perpendicular to the plane of the snapfastener and material (see Fig. 3). Apply the load until the snapfastener disengages. Remove the male end of the specimenfrom the lower clamp, reset the distance between clamps to 76mm (3 in.), snap the male specimen to the female specimen,ali
32、gn the pieces so that the fabric material edges are straightand tighten the lower clamp. Apply the load until the snapfastener disengages. Record the nature of the failure and theload at failure to the nearest 0.4 N (0.1 lbf). Repeat thisprocedure until the specimen has been tested three times.9.3 D
33、etermination of Lateral Holding StrengthUse thesame specimens prepared from snap action tests. Use the sameprocedure specified in 9.2 except that the male specimen isclamped in the upper clamp and the force is applied in a planeparallel to the material and snap fastener (see Fig. 4).10. Report10.1 S
34、tate that the tests were made as directed in TestMethod D 4846. Describe the material or product beingsampled and the method of sampling used. Describe thematerial and end product.10.2 Report the following information:10.2.1 Type of testing machine and load range used.10.2.2 Individual and average r
35、esults.10.2.3 Note any fabric or snap fastener failure beside resultswith F for fabric and S for snap fastener. Disregard fabricfailures.10.3 Report the units of force in newtons (N) or poundsforce (lbf).11. Precision and Bias311.1 Summary:11.1.1 In comparing two averages, the differences shouldnot
36、exceed the following critical differences in 95 cases out of100 when all of the observations are taken by the samewell-trained operator using the same piece of test equipmentand specimens randomly drawn from the same sample ofmaterial and tested on the same day.Snap action .61 lbs for averages of 4L
37、ateral holding strength 4.30 lbs for averages of 411.1.2 The size of the differences is likely to be affectedadversely by different circumstances. The true values of snapaction and lateral holding strength can be defined only in termsof specific test methods. Within this limitation, the proceduresin
38、 this test method for determining these properties have noknown bias.11.2 Interlaboratory Test DataAn interlaboratory test wasrun in 1996 in which randomly drawn samples of five materialswere tested in five laboratories. Each laboratory used twooperators, each of whom tested four specimens of eachma
39、terial. The components of variance expressed as standarddeviations were calculated to be the values listed in Table 1 and3Supporting data available from ASTM Headquarters. Request RR:D13-1080.FIG. 3 Specimen Clamping for Snap Action TestFIG. 4 Specimen Clamping for Lateral Holding StrengthTABLE 1 Cr
40、itical Differences Between Two Averages for Single-Material ComparisonsNames of thePropertiesNumber ofObservationsin AverageSingle-OperatorPrecisionWithin-LaboratoryPrecisionBetween-LaboratoryPrecisionSnap action 1 1.21 1.50 1.582 .85 1.24 1.335 .54 1.05 1.1510 .38 .98 1.08Lateral holding strength 1
41、 8.6 8.6 9.02 6.1 6.1 6.65 3.8 3.8 4.610 2.7 2.7 3.7D 4846 96 (2004)3Table 2.11.3 Critical DifferencesFor the components of variancelisted in Table 3 and Table 4, two averages of observed valuesshould be considered significantly different at the 95 % prob-ability level if the difference equals or ex
42、ceeds the criticaldifferences listed in Table 1 and Table 2.11.4 BiasThe procedures in Method D 4846 for measur-ing the properties listed in Tables 1-4 have no bias because thevalue of these properties can be defined only in terms of a testmethod.12. Keywords12.1 snap fasteners; strengthASTM Interna
43、tional takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely th
44、eir own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should
45、 be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standa
46、rds, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-83
47、2-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).TABLE 2 Critical Differences Between Two Averages for Multi-Material ComparisonsNames of thePropertiesNumber ofObservationsin AverageSingle-OperatorPrecisionWithin-LaboratoryPrecisionBetween-La
48、boratoryPrecisionSnap action 1 1.64 1.87 2.432 1.41 1.67 2.275 1.24 1.53 2.1710 1.18 1.48 2.14Lateral holding strength 1 11.5 11.5 12.52 9.8 9.8 10.95 8.6 8.6 9.910 8.1 8.1 9.5TABLE 3 Components of Variance as Standard Deviations forMulti-MaterialNames of the PropertiesSingle-OperatorComponentWithin
49、-LaboratoryComponentBetween-LaboratoryComponentSnap action .44 .32 .17Lateral holding strength 3.10 0 .91TABLE 4 Components of Variance as Standard Deviations forMulti-MaterialNames of the PropertiesSingle-OperatorComponentWithin-LaboratoryComponentBetween-LaboratoryComponentSnap action .84 .32 .56Lateral holding strength 5.87 0 1.75D 4846 96 (2004)4
