Aluminium Design and Construction John Dwight

else of ingenious ‘proprietary’ design. In the late 1940s, large aluminium
rivets came into use (up to 25 mm diameter), and some notable structures
were built with them. High forces were needed to close these rivets and
special squeeze-riveters were developed for the purpose. All this
disappeared with the arrival of gas-shielded arc welding in the 1950s,
combined with the fact that riveting had become a lost art generally in
the fabricating industry. But one wonders whether the rush to weld
aluminium has not been somewhat Gadarene.
Non-heat-treatable solid aluminium rivets come in 5xxx-series alloy.
For the best shear strength, they should be supplied in a work-hardened
condition (typically quarter-hard) and driven cold. To facilitate closing
(i.e. for larger rivets), they can instead be used in the annealed Ocondition,
with a slight strength penalty. In this case, they can if necessary
be driven hot, the required temperature being about 350°C. Table 11.1,
based on BS.8118, covers two typical rivet materials of this kind, 5154A
and 5056A. The latter, which is the stronger, is not recommended for
tropical environments because of possible corrosion.
The alternative is to employ rivets in heat-treatable material. These
are driven cold, normally in the solution-treated T4 condition. For the
greatest ease of closing, they should be used within two hours of
quenching, or up to four or five days if held in a refrigerator (at -6 to
-10°C). Rivets of this kind would normally be in the stronger kind of
6xxx-series alloy, such as 6082, for which strength data are included in
Table 11.1. The British Standard also includes data for rivets in the T6
condition.
Aluminium rivets should always be used in reamed holes, as they
will not tolerate a bad hole in the way that hot-driven steel rivets used
to. Because they are driven cold, or at a fairly modest temperature, they
exert negligible clamping action between the plates. On the other hand,
after driving, they fill the hole well. Aluminium rivets should not be
used in situations where they have to carry tensile loading.
The above information refers to conventional solid rivets, In the
attachment of sheet metal panels much use is made of proprietary
fasteners, which are easy to use and which are suitable for blind riveting
(access to only side of the joint). Examples of these are the well-known
‘pop’ and ‘chobert’ rivets, both of tubular form. Pop-rivets come in
diameters up to about 5 mm. They can exert a limited clamping action,
provided care is taken with plate fit-up during closing, but they do not
fill the hole so well as a cold-driven solid rivet. In contrast, the chobert
rivet, which is available in larger sizes, fills the hole well but has negligible
clamping action. A wide range of other proprietary fasteners is available,
generally more expensive, mostly for use in the aero-industry. In the
USA such fasteners, which are a cross between a bolt and a rivet, are
also popular in non-aeronautical construction.
Copyright 1999 by Taylor & Francis Group. All Rights Reserved.