ASTM D7142-05(2016)

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it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
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Designation: D7142 − 05 (Reapproved 2011) D7142 − 05 (Reapproved 2016)
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
1.1 This test method covers the determination of the holding 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 stand and force-measuring gage (Option 2).
1.2 This test method is applicable to prong-ring type snap fasteners in garments or to be attached to fabrics intended for use
in apparel (see Annex A1).
1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text, the
inch-pound units are shown in parentheses. The values stated in each system are not exact equivalents; therefore, each system shall
be used independently of the other. Combining values from the two systems may result in non-conformance with the specification.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
D76 Specification for Tensile Testing Machines for Textiles
D123 Terminology Relating to Textiles
D1776 Practice for Conditioning and Testing Textiles
2.2 Federal Document:
16 CFR Parts 1500.48-1500.53 and 1501.4 Engineering Test Manual for Children’s Toys
3. Terminology
3.1 Definitions:
3.1.1 force, n—a physical influence exerted by one body on another which produces acceleration of bodies that are free to move
and deformation of bodies that are not free to move.
3.1.2 holding strength, n—in snap fasteners, the force required to separate the prong-ring from its attached mating part (socket
or stud).
This test method is under the jurisdiction of ASTM Committee D13 on Textiles and is the direct responsibility of Subcommittee D13.54 on Subassemblies.
Current edition approved Jan. 1, 2011Oct. 1, 2016. Published March 2011October 2016. Originally approved in 2005. Last previous edition approved in 20052011 as
D7142D7142 – 05 (2011). - 05. DOI: 10.1520/D7142-05R11.10.1520/D7142-05R16.
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 the ASTM website.
Available from Federal Register, Vol 44, No. 117, June 1979, Consumer Product Commission, 16 CFR Parts 1500 and 1501.
3.1.2.1 Discussion—
In this test method, a diametric force is applied which simulates the diametric biting or pinching of a child; however, in practice,
the disengaging force used to unsnap a snap fastener is usually applied at the edge of the fastener.
3.1.3 prong-ring type fastener, n—generic name for snap fasteners which use a multi-pronged ring to penetrate through fabric
to mechanically set a matching socket on one side of a closure and to set a matching stud on the facing closure allowing the outer
and inner closure facings to be snapped together. (See Fig. 1.)
3.1.4 socket, n—in snap fasteners, the female functional part of the fastener which engages with the stud part of the fastener
to form the closure of two parts of the item on which the fastener is used. (See Fig. 1.)
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D7142 − 05 (2016)
FIG. 1 Prong-ring Attached Fastener Parts
3.1.4.1 Discussion—
Prong-ring attached socket or stud snap fasteners are designed to be mechanically attached to garments or other items through the
deformation interaction of the prong-ring with the socket or stud. Other forms of snap fasteners exist which may be attached to
the foundation of the garment or other item by means of sewn threads or adhesive bonding.
3.1.5 strength, n—the property of a material that resists deformation induced by external forces.
3.1.5.1 Discussion—
In this standard, the deformation is the separation of the prong-ring from the socket or stud of a snap fastener.
3.1.6 stud, n—in snap fasteners, the male functional part of a snap fastener which engages with, or snaps into, the mouth of the
socket to form a closure of two parts of the item, or garment on which the fastener is used. (See Fig. 1.)
3.1.6.1 Discussion—
See discussion for socket.
3.1.7 For definitions of other textile terms used in this standard, refer to Terminology D123.
4. Summary of Test Method
4.1 Option 1—A specimen, consisting of a fastener socket or stud attached to fabric by a prong-ring, is mounted in a special
test fixture on a tensile testing machine. A force is applied diametrically until the prong-ring separates from the socket or stud, or
the fabric is torn. The force at separation is reported as the holding strength. 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 is reported separate from the holding strength of the
fasteners.
4.2 Option 2—A specimen, consisting of a fastener socket or stud attached to fabric by a prong-ring, is mounted in a special
test fixture on a manual pull test stand which is fitted with a portable force gage. A force is applied until the prong-ring separates
from the socket or stud, or the fabric is torn. The force at separation is reported as the holding strength. 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 is reported separate from the
holding strength of the fasteners.
5. Significance and Use
5.1 Both test methods are considered satisfactory for acceptance testing of commercial shipments of garments with prong-ring
type snap fasteners.
5.1.1 In case of dispute arising from differences in reported test results when using this test method for acceptance of
commercial shipment, the purchaser and the supplier should conduct comparative tests to determine if there is a statistical bias
between their laboratories. Competent statistical assistance is recommended for the investigation of bias. As a minimum, the two
parties should take a group of test specimens that are as homogeneous as possible and that are from a lot of material of the type
in question. The test specimens should then be randomly assigned in equal numbers to each laboratory for testing. The average
D7142 − 05 (2016)
results from the two laboratories should be compared using appropriate statistical analysis and an acceptable probability level
chosen by the parties before testing is begun. If a bias is found, either the cause must be determined and corrected, or the purchaser
and supplier must agree to interpret future test results with consideration to the known bias.
5.2 Comparison of results from test equipment operating on different principles is not recommended. In cases of conflict
between the test results achieved with manual test equipment (Option 2) and motorized CRE (constant rate of extension) tensile
testing machine (Option 1), the results from the motorized equipment shall take precedence.
5.3 This test method may be used to determine the compatibility of prong-ring type snap fasteners and fabrics for use in apparel.
In which case, the fasteners are attached to the fabric in the manner in which they will be used and the combined units tested. See
Annex A1.
6. Apparatus
6.1 For Option 1:
6.1.1 Tensile Testing Machine, CRE type, meeting Specification D76. (See Figs. 2 and 3.)
6.1.2 Upper Snap Fixture Attachment 4, Fig. 4, designed to diametrically attach to the socket or stud of the snap fastener which
is attached to the fabric specimen or garment being tested.
6.1.3 Lower Snap Fixture Attachment 4, Fig. 4, designed to secure the fabric and thereby the socket or stud attached to it in
a horizontal plane.
6.2 For Option 2:
6.2.1 Force Measuring Gage 5, modified with an attachment to be fastened on to the upper arm of a test stand with the upper
test fixture suspended from it. (See Fig. 3.)
6.2.2 Upper Snap Fixture Attachment 4, Fig. 4, designed to diametrically attach to the socket or stud of the snap fastener which
is attached to the fabric specimen or garment being tested.
6.2.3 Lower Snap Fixture Attachment 4, Fig. 4, designed to secure the fabric and thereby the socket or stud attached to it in
a horizontal plane.
6.2.4 Test Stand, see Fig. 5.
FIG. 2 CRE-Type Tensile Testing Machine setup With Test Fixtures For Option 1.
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FIG. 3 Closeup of CRE-Type Tensile Testing Machine Fixture Setup.
7. Sampling
7.1 Lot Sample:
7.1.1 For acceptance testing, randomly select the number of shipping car
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