ASTM D5170

ASTM D5170 – Standard Test Method for Peel Strength (“T” Method) of Hook and Loop Touch Fasteners

Description:

Significance and Use

3.1 This test method gives a measure of a key property of hook and loop touch fasteners which is of interest to users of such devices. This is a means of determining the resistance to separation when forces are applied normal to the line of separation of the fastener.

3.2 The force registered in a peel test is irregular, and as a consequence, empirical methods have had to be developed to obtain usable values related to peel strength. In spite of the empirical nature of the reported values, it is believed they reflect comparative performance of similar touch fasteners tested and measured in the same way.

3.3 Two optional methods of calculation are provided: integrator average and average of five highest peaks. These test methods are not equivalent. Generally, the integrator average will be lower than the average of the five highest peaks.

3.4 The highest peaks which reflect the force required to separate a hook and loop closure bear no simple relationship to the average force (integrator average). The average of the five highest peaks better reflect performance but the integrator results may be used to characterize a closure and for quality control purposes. The integrator average is relatively easy to calculate given the proper equipment.

3.5 In the case of a dispute arising from differences in reported test results when using this test method for acceptance testing of commercial shipments, 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 which are as homogenous as possible and which are from a lot of hook and loop of the type in question. The test specimens should then be randomly assigned in equal numbers to each laboratory for testing. The average results from the two laboratories should be compared using Student’s t-test and an acceptable probability level chosen by the two parties before the testing began. If a bias is found, either its cause must be found and corrected or the purchaser and the supplier must agree to interpret future test results in the light of the known bias.

Scope

1.1 This test method covers the measurement of the peel strength of hook and loop touch fasteners using a recording constant-rate-of-extension tensile testing machine (CRE).

1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.