Page 60 - Welding of Aluminium and its Alloys

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Preparation for welding

4.1 Introduction
The need for degreasing and oxide removal has been covered in Chapter
2.This chapter will review both the handling and storage of aluminium and
the options available for cutting, machining and pickling and cleaning of
the alloys prior to welding. There are a number of thermal processes avail-
able to the fabricator for either cutting or weld preparing, as discussed in
this chapter. One process that is not available for the cutting of aluminium,
however, is the oxy-gas process used so widely to cut the carbon and
low-alloy steels. Instead, arc or power beam processes or machining must
be used to provide the correct edge preparations for welding.
Correct and accurate edge preparations are essential for the production
of sound, defect-free welds in aluminium. Edge preparations are required
to achieve full penetration to the root of the joint, to enable the correct
analysis of weld metal to be achieved, to assist the welder to produce defect-
free joints and to do this at an acceptable cost. The design of edge prepa-
rations for specific welding processes will be dealt with in the chapters
dealing with the individual processes.

4.2 Storage and handling

Good handling practices are required if aluminium components are to be
supplied to the customer in an unmarked condition. Aluminium is a rela-
tively soft material and is easily scored or dented by clumsy handling or the
use of inappropriate lifting equipment. Over-centre edge clamps, commonly
used on steels, can score plate edges and steel chains can produce scratches
and dents. A solution to marking by clamps is to face the jaws with a soft
material – wood or polythene blocks are excellent as packing materials.
Lifting should be carried out with nylon ropes or webbing straps. Remem-
ber that these softer materials are far more easily damaged than steel and
more regular maintenance of any lifting equipment will be necessary. Hard

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