News & insight

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

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

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

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.

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

Improved tool accuracy and process control helps, but preload scatter cannot be eliminated. Critical joints should be validated through testing.

This is an industry convention for metal-to-metal joints and is not sufficient for composite or bonded structures. Use alternative governing criteria whenever fastened materials, interfaces, or performance requirements impose additional limits.

Because torque is only an indirect way of controlling clamp load, and clamp-force limits in composite and bonded structures are governed by the fastened materials and interfaces, not the bigHead fastener alone.

No. A given tightening torque will produce a range of preload values due to normal variations in friction and tool accuracy. This preload scatter is unavoidable and is influenced by surface condition, lubrication, materials, and the assembly method used.

It depends on what you need to protect or control. Use torque limits to protect the bigHead collar from thread strip, or the embedding/bonded interface from excessive torsional loading. Use preload limits to manage clamp load and compressive forces in the fastened materials, or comply with the axial load limits of the fasteners. In some applications, both limits apply. The…