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Table 1
Brief description of DIN 25201-4 B, ISO 16130, NASM 1312-7 and “tested-by-me” protocols.
Brève description des normes DIN 25201-4 B, ISO 16130, NASM 1312-7 et d’un protocole ≪ testé-par-moi ».
| DIN 25201-4 B The toughest conditions |
ISO 16130:2015 The standard for aerospace |
NASM1312-7 For impact testing |
Bespoke “tested-by-me” protocols |
|---|---|---|---|
| The DIN 25201-4 B, published in 2010, supersedes DIN 65151 and is significantly more rigorous. It introduces mandatory reference and verification tests, specifies quality tolerances on the fastener adaptors in the test fixture, requires the use of a test washer, sets a standardised clamp ratio, defines the initial preload level and sets out strict test reporting procedures. The DIN 25201-4 B also sets criteria for evaluating whether a locking element has adequate self-locking behaviour. |
The ISO 16130 is not as rigorous as DIN 25201-4 B but follows similar principles. It defines new tolerances on the test machine. It introduces torque measurements into a vibration test standard. Finally, ISO 16130 sets evaluation thresholds and specifies three quality levels for evaluating the self-locking behaviour of bolted joints. |
The “Fastener Test Methods 7 Vibration” was published by the Aerospace Industries Association of America in 1997 and is quite different from the Junker test. This test is an impact and shock test that involves securing the fasteners to be tested in cylinders mounted in slots within a reciprocating fixture. The fixture is vibrated at 30 Hz at an amplitude, peak to peak, of 0.45 inches (11.4 mm). A problem with using this test to assess the self-loosening of fasteners is that the bolt preload is not measured during testing. |
These protocols represent an important experimental approach to testing for the real world. Testing products to meet specific performance characteristics beyond the conditions specified in the formal standards requires innovative testing strategies designed to replicate the real service conditions. This is a common-place occurrence in the automotive and defence-aerospace sectors, and the practice is spreading into other sectors. ‘Tested-by-me’ product development strategies result in improved products over the long term and a competitive edge that can be sustained. |
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