Tensile tests are a fundamental aspect of quality assurance for threaded fasteners and are used to determine both breaking load and strain under axial loading. Available from Zwick is a flexible testing system for tests up to Fmax 600 kN.

Threaded fasteners are subject to strict safety requirements as defined in ISO 898-1 and ISO 3506-1. Key requirements for the testing system include secure clamping of the fastener, the ability to accommodate different thread sizes and measurement of strain under tensile loading. Zwick has supplied a standardized solution to one of Korea’s biggest manufacturers of threaded fasteners.

The testing system for tensile tests up to Fmax 600 kN is equipped with special specimen grips (also Fmax 600 kN) for threaded fasteners. Head inserts and threaded inserts for fasteners from M4 to M36 enable fast, secure insertion of the fasteners into the testing machine. As well as tests to determine the maximum breaking force (ISO 898-1), strain can be measured during the tensile test (ISO 3506-1) using a special extensometer. For this the extensometer measuring-transducer is attached to the ends of the fastener. The specimen grips are designed to allow precise, straightforward attachment of the extensometer.

Performance and evaluation of the test are via testXpert II testing software. Major selling points for the Koreans were ease of operation combined with Zwick’s wide-ranging expertise in testing metals and threaded fasteners.