ASTM D4846-96 (R2021) pdf free download.Standard Test Method for Resistance to Unsnapping of Snap Fasteners.
1.1 This test method covers the determination of the force required to disengage snap fasteners by a pull perpendicular to and parallel with the plane of the snap fastener.
I .2 This test method requires attachment of snaps to specimens using specifications provided by the producers of the snaps.
1.3 This test method is used to establish correlation to wear conditions and for comparing different brands and types of snap fasteners.
1.4 The values stated in SI units arc to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard.
3. Definitions
3. 1 lateral holding strength, n—the force required to disengage a snap fastener resulting from a pull in the plane parallel to the material to which the snap fastener is attached.
3.2 snap action, n—the force required to disengage a snap fastener resulting from a pull exerted perpendicular to the plane of material to which the snap fastener is attached.
3.3 snap fasienei; n—a device for attaching one material to another consisting of matching male and female parts, each of which is attached to a separate material so that the parts can be joined by a low compressive force and separated by a low perpendicular tensile force.
3.4 For definitions of other textile terms used in this test method, refer to Terminology Dl23.
4. Summary of rrt Method
4.1 Snap fasteners mounted on strips of material near the end are tested on standard tensile testing machines equipped for testing the strength of textile fabrics and having sensitivity for accurate low force levels.
4.2 Tests are made on snap fasteners before laundering with the option of testing again after a pre-determined number of launderings or other types of refurbishing.
5. Significance and Use
5.1 This test method may be used for acceptance testing of commercial shipments of snap fasteners, hut caution is advised since information on between laboratory precision is incomplete. Comparative tests as directed in 5.1.1 are advisable.
5.1.1 In case of a dispute arising from differences in reported test results when using Test Method D4846 for acceptance testing of commercial shipments, the purchaser and seller should conduct comparative tests to determine if there is 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 then should be assigned randomly in equal numbers to each laboratory for testing. ASTM D4846 pdf download.