Fasteners: what are they, why are they used and how are they installed?

The application of fasteners is one of the crucial steps in light metalwork in the service of electronics. Also called ‘inserts’ or ‘fasteners’, fasteners have been used in industry for more than 80 years and are basically self-clinching mechanical devices that create solid connection points between even particularly thin sheets (0.8 mm to 4 mm).

They are called self-clinching systems because, by exploiting specific installation processes, they manage to become integral elements with the laminate in which they are inserted. In fact, the use of presses equipped with specially designed punches and dies makes it possible to apply the correct pressure on the fastening point and obtain the desired result: the special profile of the head, through the use of undercuts, allows the metal of the laminate to deform and firmly embrace the fastener.

Why were fasteners invented and where are they used?

The origin of fasteners can be found in the automotive industry and is the result of the need to find viable alternatives to welding and gluing, especially when handling thinner laminates. Over time, the efficiency of fasteners has allowed these particular fasteners to find application in many different areas.

Thanks to their versatility, today they are also widely used in the electronic devices sector. Here, they act as robust support and attachment elements, but also serve to provide correct distances to electronic elements that require a thin laminate case.

There are many different types of fasteners, each with a specific use depending on its purpose. For the management of its production processes, elmec has chosen to refer to the PEM catalogue, a leading brand of fasteners and installation systems dedicated to sheet metal, PCBs (Printed Circuit Boards) and plastics.

Fastener installation

If the choice of the most reliable fasteners is crucial to the success of operations, the same can be said of the way fasteners are installed. The application of fasteners is simple, but at the same time extremely delicate and requires both a good deal of experience and the use of state-of-the-art machinery.

For the installation of fasteners on your mechanical devices, the elmec team uses pneumatic presses capable of providing the correct pressure between the die and the punch, so that the fasteners are engaged. How does the procedure work? First of all we prepare a hole with a specific tolerance on the sheet metal, at the point where the desired insert will be inserted. At this point it will be the job of the punch to press the insert onto the sheet metal, causing the crown of the insert to sink into the thickness of the sheet metal and self-latch solidly onto it.

To make the application of fasteners effective and efficient, it is indispensable to always maintain a correct distance from the sheet edge, but also to carry out a specific tolerance on the diameter of the preparation hole and choose the most suitable punch according to the type of insert. Finally, it is crucial to set the correct pressure parameters on the machine, in relation to the thickness of the laminate and the type of fastener selected.

Customisation comes first: is it possible to make customised fasteners?

If your project requires the use of non-standard fasteners (e.g. if you need specific heights or unusual diameters), then it is possible to create a customised insert for your needs.

We can make customised fasteners with the help of automatic lathes, using materials other than the usual ones, such as AVP, INOX 303 and brass. Obviously, each technology used has specific peculiarities, which must be respected during machining and which may concern different details, such as measurements or production volumes.

Do you have questions regarding fasteners and their possible use within your mechanical projects? Contact us to see how we can create, together, a truly high-performance result.