Page 61 - Welding of Aluminium and its Alloys

52 The welding of aluminium and its alloys

particles can also become embedded in the packing or lifting strops, result-
ing in marking of the components.
Storage is important if the surface condition of the aluminium is not to
suffer. Ideally, items should be stored indoors in a dry, clean and well-
ventilated storage area. Storing plates flat may give rise to water staining
from condensation collecting on the surface. This can be particularly dam-
aging if the plates are stacked directly one on top of another, when a thick
layer of hydrated oxide can rapidly form at the interface. Plates should
always be separated in storage and ideally stacked on edge to provide good
air circulation. This reduces the risk of accumulating water and dirt on the
flat surfaces and prevents other items being stored on top. It also assists in
reducing the risk of scratches from dragging plates off the stack.

4.3 Plasma-arc cutting

Plasma-arc may be used for either cutting or welding and is the most
widely used thermal process for cutting of aluminium alloys in manual,
mechanised or fully automated modes (Fig. 4.1). In the latter case cuts of
excellent quality can be achieved in material of up to 250mm thickness
at high cutting speeds.

4.1 Fully programmable CNC plasma-jet cutting system. Courtesy of
Messer Griesheim.