Aluminium Design and Construction John Dwight

y the welding tool. This calls for the design of special FS welding
machines, either with the job moving past a fixed welding head, or else
with the job stationary and the welding head moving, the latter
arrangement being necessary for making very long welds. (Early
experiments made use of a suitably modified milling machine, the travel
on which limited the possible length of weld.)
Another snag is that a hole remains at the end of each weld run,
formed when the tool is withdrawn. This has to be filled in somehow,
an available method being friction taper plug welding. As with arc welds,
run-on and run-off plates are generally necessary, unless it is possible
to cut off the end material.
3.4.4 Applications
A major role for the FS process is likely to be in the manufacture of
large areas of stiffened plating, by welding together long lengths of
extruded planking. Such a product is attractive in truck bodies, ships,
offshore modules and bridges. The equipment can also be installed in
extrusion plants, where it provides an economic means of supplying
wide sections by welding together narrower ones, thus avoiding the
high capital cost of a very large press. Such a technique can be employed
for making double-skin stiffened plating, by welding together plank sections
of rectangular hollow profile, using an FS weld on either surface.
3.5 OTHER WELDING PROCESSES
Resistance welds are readily made in aluminium, generally with a higher
energy input than with steel. Spot welding of car bodies is standard,
latterly in conjunction with adhesive bonding. But flash-butt welding
of window frames has entirely given way to mechanical joints. Other
forms of friction welding (beside friction-stir) are also available.
3.6 ADHESIVE BONDING
3.6.1 Use of bonding
As a connection technique for aluminium, adhesive bonding has features
that often make it a valid alternative to bolting, riveting or welding
(Section 11.4.1). But its successful use is critically dependent on good
practice by the fabricator, especially as regards preparation of the surfaces.
Adhesives used with aluminium are usually epoxy materials, two
main types being available: the two-component and the one-component.
None are covered by official standards in the way that metal products
Copyright 1999 by Taylor & Francis Group. All Rights Reserved.