The Fastenering is a technique of mechanical joining of materials more precisely performed through the use of “fastners”. This coupling method is still used in many mechanical joints, replacing metallic materials for the various coupling techniques by welding and non-metallic materials as a complement to the various coupling techniques such as adhesive, providing excellent mechanical strength and benefits on total weight. 

The fastener is a mechanical jointmomg  and above all no longer separable, is fully part of the “special processes”. because the removal can only take place by means of its destruction, and the verification of correct application only through destructive tests.

The fastener consists of a tube with a cylindrical shape that includes on one side the head of the fastner. Has in its interior a plug that TRACTION with proper equipment deforms the opposite end of the cylinder forming the tailstock.

The use of a mechanical splice fastner sheet metal must consider some fundamental aspects, mechanical, aesthetic and functional:

Compatibility of the materials used for the realization of the coupling, including the fastener;

The geometric shape of the joint (Available surfaces for the insertion of the fastener);

The thickness of the joint (thick coats do not provide structural strength of the joint);

The application of the fastener (processing and application of the fastner);

Structural strength of the coupling, using the fastner to a shear stress;

Accuracy in surface preparation application of the fastener (if used drilling and countersinking a fastner countersunk head);

Equipment suitable for the application;

Finish surface appearance.

The design of a mechanical joint by fastenering, is done by defining:

Materials subject to junction (type of material);

Main characteristics of mechanical resistance of the material including the breakdown voltages of the material.

Stress on the joint;

Performance requirements.

Type of fastner;

The choice of the fastener (material, shape, size) is subject to the structural calculations in consideration of the materials used, stress and performance.

Arrangement of the fastener on the coupling;

Incorrect disposal of the fastner prevents the transmission of loads between the various parts of the component, the various tensile concentrating only on some specific points.

Application of the fastener;

Simplicity in the application to guarantee high performance and increased productivity.

Qualification tests of the joint.

A series of tensile tests performed to verify performance requirements.

The test consists in breaking the joint by axial traction with increasing loads.

Are cited below are some regulations regarding:

EN ISO 3269 “Fasteners – Acceptance inspection”

BS EN 10045-1 “Metallic materials. Charpy impact test. Part 1: Test method (classification index: A 03-011).

BS EN 10002-2 “Metallic materials. Tensile testing. Part 2: verification of the force measuring system of the tensile testing machines (classification index: A 03-002). “