Q: What does ASTM D2061 measure on a zipper assembly?
ASTM D2061 groups the mechanical strength tests used on zippers. It covers the force needed to pull the slider off the chain, the holding strength of the top and bottom stops, the crosswise strength of the closed chain, and the pull-off force of the pull from the slider body. Each test has its own fixture and its own way of gripping the specimen, so results from different methods are not interchangeable.
The tests run on a constant-rate tensile machine. Specimens are conditioned, mounted in the specified grips, and loaded until failure at the rate set in the method for that test, with the peak force recorded. Report the mode of failure as well as the number: a stop that pulls out of the tape and a stop that breaks are different findings for the supplier. Gauge length, grip type and speed are defined per test, so refer to the standard text.
Acceptance is by specification or by the agreed drawing, not by a general minimum. Test a defined number of specimens from each lot or colour and judge the lowest result, not the mean, when the risk is a single weak part.