Sheet Metal Work

While the majority of metals can be rolled into sheet form, consideration is confined to the working with sheets of the light alloys, which are encountered on aircraft and in particular, those formed from aluminium alloy ingots. The sheets of aluminium alloy have comparatively thin cross-section. And they not only pose a health hazard through cuts, but also prone to buckling and creasing if handled carelessly.

Large sheets of aluminium alloys are, usually stored upright on their longest edge and supported in a wooden framework so they are protected from damage and corrosion. Care must be taken when removing a large sheet from its storage rack – a task which normally involves at least two persons. And good communication between the carriers is important so that the task is completed in a safe manner and no damage is done to the sheet metal.

Some sheets are covered on one or both surfaces, with a thin protective plastic membrane. If possible, it may be beneficial to leave at least the underneath protection in place while the marking out is done, to minimise the possibility of the surface sustaining undesirable scratch marks. If no protective membrane is applied to the sheet, then care must be taken over the condition of the surface of the table or workbench, upon which the sheet is to be laid for the marking out procedures.

Other factors, which should be considered (as with all work) concern the requirements to ensure that:

• Material wastage is kept to a minimum
• The task is done correctly for the first time, so that valuable time is not wasted.

The first point is usually obvious, due to the cost of the materials involved, but the second point quite often gets forgotten, when work is being done, but the actual labour costs far outweigh the material costs on a high percentage of tasks.

Repair or modification drawings must be studied very carefully, to ensure there is no doubt about the data and dimensions provided, so that the marking out is correctly done and the approved metal is shaped in exactly the manner that the designer of the drawing intended.