FAQs

Testing bigHead fastener installations

• What do axial tests measure – are they testing the bigHead fastener itself?

  No. Axial tests measure the performance of the installed system – the fastener, substrate, and adhesive (where used) – not the standalone fastener.

• Why are there three axial test methods?

  Each method corresponds to a different installation configuration and axial loading direction.

  Depending on the configuration, the fastener, substrate, and adhesive (where used) contribute differently to the mechanical performance of the fastening system. Therefore, results cannot be compared between the three test methods.

• Why do axial test results vary between apparently similar samples?

  Small differences in substrate composition, adhesive coverage, cure quality, or installation alignment can significantly affect axial strength and failure mode.

• Why do loading arrangements differ between the test methods?

  To ensure the fastening system is loaded in a way that reflects real-world behaviour.

• Why must aperture and coupon sizes follow the specified dimensions?

  Correct sizing ensures the fixture properly supports polymer and polymer-composite substrates, and keeps results comparable across different bigHead Head types.