ASTM D7142-05(2021)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D7142 − 05 (Reapproved 2021)
Standard Test Method for
Holding Strength of Prong-Ring Attached Snap Fasteners
This standard is issued under the fixed designation D7142; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2.2 Federal Document:
16 CFR Parts 1500.48-1500.53 and 1501.4 Engineering Test
1.1 Thistestmethodcoversthedeterminationoftheholding
Manual for Children’s Toys
strength of a prong-ring to the socket or stud of a snap fastener
using a tensile testing machine (Option 1) or a manual test
3. Terminology
stand and force-measuring gage (Option 2).
3.1 Definitions:
1.2 This test method is applicable to prong-ring type snap
3.1.1 force, n—a physical influence exerted by one body on
fasteners in garments or to be attached to fabrics intended for
another which produces acceleration of bodies that are free to
use in apparel (see Annex A1).
move and deformation of bodies that are not free to move.
1.3 The values stated in either SI units or inch-pound units
3.1.2 holding strength, n—in snap fasteners, the force re-
are to be regarded separately as standard. Within the text, the
quired to separate the prong-ring from its attached mating part
inch-pound units are shown in parentheses. The values stated
(socket or stud).
in each system are not exact equivalents; therefore, each
3.1.2.1 Discussion—In this test method, a diametric force is
system shall be used independently of the other. Combining
applied which simulates the diametric biting or pinching of a
values from the two systems may result in non-conformance
child; however, in practice, the disengaging force used to
with the standard.
unsnap a snap fastener is usually applied at the edge of the
1.4 This standard does not purport to address all of the
fastener.
safety concerns, if any, associated with its use. It is the
3.1.3 prong-ring type fastener, n—generic name for snap
responsibility of the user of this standard to establish appro-
fasteners which use a multi-pronged ring to penetrate through
priate safety, health, and environmental practices and deter-
fabric to mechanically set a matching socket on one side of a
mine the applicability of regulatory limitations prior to use.
closure and to set a matching stud on the facing closure
1.5 This international standard was developed in accor-
allowing the outer and inner closure facings to be snapped
dance with internationally recognized principles on standard-
together. (See Fig. 1.)
ization established in the Decision on Principles for the
3.1.4 socket, n—insnapfasteners,thefemalefunctionalpart
Development of International Standards, Guides and Recom-
of the fastener which engages with the stud part of the fastener
mendations issued by the World Trade Organization Technical
to form the closure of two parts of the item on which the
Barriers to Trade (TBT) Committee.
fastener is used. (See Fig. 1.)
2. Referenced Documents
3.1.4.1 Discussion—Prong-ringattachedsocketorstudsnap
2 fasteners are designed to be mechanically attached to garments
2.1 ASTM Standards:
or other items through the deformation interaction of the
D76/D76M Specification for Tensile Testing Machines for
prong-ring with the socket or stud. Other forms of snap
Textiles
fasteners exist which may be attached to the foundation of the
D123 Terminology Relating to Textiles
garment or other item by means of sewn threads or adhesive
D1776/D1776M Practice for Conditioning and Testing Tex-
bonding.
tiles
3.1.5 strength, n—the property of a material that resists
deformation induced by external forces.
This test method is under the jurisdiction ofASTM Committee D13 on Textiles
3.1.5.1 Discussion—In this standard, the deformation is the
and is the direct responsibility of Subcommittee D13.54 on Subassemblies.
separation of the prong-ring from the socket or stud of a snap
Current edition approved July 1, 2021. Published August 2021. Originally
approved in 2005. Last previous edition approved in 2016 as D7142 – 05 (2016). fastener.
DOI: 10.1520/D7142-05R21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Available from Federal Register, Vol 44, No. 117, June 1979, Consumer
the ASTM website. Product Commission, 16 CFR Parts 1500 and 1501.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7142 − 05 (2021)
FIG. 1 Prong-ring Attached Fastener Parts
3.1.6 stud, n—in snap fasteners, the male functional part of mens that are as homogeneous as possible and that are from a
a snap fastener which engages with, or snaps into, the mouth of lot of material of the type in question. The test specimens
thesockettoformaclosureoftwopartsoftheitem,orgarment should then be randomly assigned in equal numbers to each
on which the fastener is used. (See Fig. 1.) laboratory for testing. The average results from the two
3.1.6.1 Discussion—See discussion for socket. laboratories should be compared using appropriate statistical
analysis and an acceptable probability level chosen by the
3.1.7 For definitions of other textile terms used in this
parties before testing is begun. If a bias is found, either the
standard, refer to Terminology D123.
cause must be determined and corrected, or the purchaser and
supplier must agree to interpret future test results with consid-
4. Summary of Test Method
eration to the known bias.
4.1 Option 1—A specimen, consisting of a fastener socket
or stud attached to fabric by a prong-ring, is mounted in a
5.2 Comparison of results from test equipment operating on
special test fixture on a tensile testing machine. A force is
different principles is not recommended. In cases of conflict
applied diametrically until the prong-ring separates from the
between the test results achieved with manual test equipment
socket or stud, or the fabric is torn. The force at separation is
(Option 2) and motorized CRE (constant rate of extension)
reported as the holding strength. If the fabric tears, the force at
tensile testing machine (Option 1), the results from the motor-
fabric failure is recorded and the data is reported and it is
ized equipment shall take precedence.
consideredasadifferentcategoryandisreportedseparatefrom
5.3 This test method may be used to determine the compat-
the holding strength of the fasteners.
ibility of prong-ring type snap fasteners and fabrics for use in
4.2 Option 2—A specimen, consisting of a fastener socket
apparel. In which case, the fasteners are attached to the fabric
or stud attached to fabric by a prong-ring, is mounted in a
in the manner in which they will be used and the combined
special test fixture on a manual pull test stand which is fitted
units tested. See Annex A1.
with a portable force gage. A force is applied until the
prong-ring separates from the socket or stud, or the fabric is
6. Apparatus
torn.Theforceatseparationisreportedastheholdingstrength.
6.1 For Option 1:
If the fabric tears, the force at fabric failure is recorded and the
data is reported and it is considered as a different category and
6.1.1 Tensile Testing Machine, CRE type, meeting Specifi-
is reported separate from the holding strength of the fasteners.
cation D76/D76M. (See Figs. 2 and 3.)
6.1.2 Upper Snap Fixture Attachment 4, Fig. 4, designed to
5. Significance and Use
diametrically attach to the socket or stud of the snap fastener,
5.1 Both test methods are considered satisfactory for accep-
which is attached to the fabric specimen or garment being
tance testing of commercial shipments of garments with
tested.
prong-ring type snap fasteners.
6.1.3 Lower Snap FixtureAttachment 4, Fig. 4, designed to
5.1.1 In case of dispute arising from differences in reported
secure the fabric and thereby the socket or stud attached to it in
test results when using this test method for acceptance of
a horizontal plane.
commercial shipment, the purchaser and the supplier should
6.2 For Option 2:
conduct comparative tests to determine if there is a statistical
bias between their laboratories. Competent statistical assis- 6.2.1 Force Measuring Gage 5, modified with an attachment
tance is recommended for the investigation of bias. As a tobefastenedontotheupperarmofateststandwiththeupper
minimum, the two parties should take a group of test speci- test fixture suspended from it. (See Fig. 3.)
D7142 − 05 (2021)
FIG. 2 CRE-Type Tensile Testing Machine Setup with Test FIG. 3 Closeup of CRE-Type Tensile Testing Machine Fixture
Fixtures For Option 1 Setup
of garments from each laboratory sampling unit to obtain the
6.2.2 Upper Snap Fixture Attachment 4, Fig. 4, designed to
ten snap fasteners. If garment has snaps attached to multiple
diametrically attach to the socket or stud of the snap fastener
locations; that is, collar, shoulder, placket, front, crotch, leg
which is attached to the fabric specimen or garment being
cuff, and the like, take appropriate number o
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