Fasteners and Sealing
Fig. 1. Supercar Carbon Fibre Diffuser Panel, with inset photo showing a close up of the bigHead Bonding Fastener.
Bonding fasteners suitable for composite panels
Bonding fasteners require no depth of material to provide a very strong and reliable fastening. Matthew Stevens reports.
M 44
www.engineerlive.com
anufacturers everywhere, from the makers of cars, trains, boats and buses to the construction industry are increasingly using composite panels. The desire to reduce weight while maintaining strength continues
to drive demand. However, users of composite panels are often faced with the problem of how to fasten or fix these panels in place.
Steel, stone and concrete
Fastening solutions that worked for solid panels of steel, wood, stone or concrete are often ineffective with composite panels made with thin sheets of carbon fibre, aluminium or plastic. Traditional fastening methods such as rivets, spot welds,
inserts, screws and bolts are sometimes no good. For a panel with skins only 3mm thick, an insert requiring solid 15mm material thickness is no use. For a lightweight cladding tile of 15mm depth, an anchor bolt designed for 75mm is useless. Bonding fasteners are increasingly seen as the answer. When surface bonded with adhesive, bonding fasteners require no depth of material to provide a very strong and reliable fastening.
When embedded in the panel, bonding fasteners with heads as thin as 1.5mm need very little panel depth to provide a very strong and reliable fastening. Bonding fasteners are also discrete and highly versatile. The automotive sector contains many good examples for
the use of bonding fasteners. One example is a supercar manufacturer’s use of bonding
fasteners to attach a carbon fibre diffuser panel. Twelve bigHead Bonding Fasteners are surface mounted to the 2-3mm thick carbon fibre plate with adhesive. The fastener provides simple threaded screw fixings with which the plate is securely bolted to the car structure. Fig. 1. shows how the adhesive flows through the holes in the bonding fastener head to secure the bonding fastener in position.
Building renovation
An interesting example from the construction sector is the renovation of an old building in central London. The project included the cladding of an interior atrium with stone panels. Due to the age of the building lightweight thin panels
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