Aircraft Manufacturing

How thin metal sheets are made depend largely on the alloy, but most compressible and stretchable metals are thinned in a similar fashion. One example of an odd case is aluminum. Pure aluminum is soft and a bit fragile, but it can be made stronger or more flexible depending on a variety of additives. Turning aluminum into a construction material has always been big business, and Sheet Metal Fabrication is a modern marvel.

More information on Sheet Metal Fabrication

The case of aluminum is important because of its use in aircraft and vehicles to replace heavier steel parts. Aluminum is much cheaper than titanium, and it can be made stronger in several ways. Some alloys of aluminum can be rolled as thin as foil while other alloys form large crystals that tend to fracture when bent.

Most metal sheets are formed by rolling a thicker stock into thin sheets. This does not happen all at once, but instead a stock must run through many different presses to achieve the desired thickness. The first pass always applies the most pressure, but as the sheet becomes thinner, a larger roller is used that applies less pressure. As the sheet becomes longer, different conveyor belts are needed to support it.

Some metals become more malleable as they heat up, and rolling metal does create a lot of heat. This can be good news for iron and steel, which have historically been worked hot, but it is bad news for metals whose working properties become less reliable as they heat up. Rolling metal thinner also alters its properties, as crystals become smashed and stretched. The resulting sheets can be more flexible than otherwise possible, as cast aluminum is rigid while aluminum foil is very pliable.

Sheet metal fabrication is very important to building airplanes. The entire machine must be able to withstand the pressure of high wind speed and uplift on the wings but must also be lightweight. Without a light build, aircraft wings would not be able to hold the craft and would break if harsh pressures were applied.

To make a lightweight aircraft, a strategic skeleton is used. Much of it is steel bars that are shaped in such a way that the greatest strength is achieved with the least amount of metal. An example is using an I-shaped beam in skyscrapers because this shape is nearly as strong as a solid steel beam. Aircraft go further by inserting odd shapes and holes into the steel bars. Many joints are made of cast aluminum rather than steel.

An ideal aircraft would be made largely of titanium, but titanium is so expensive that it is only used where absolutely necessary. Certain parts of the plane have to deal with high temperatures or endure much stress. Titanium is used for specific joints and surfaces, and cheaper metal is used for the rest.

Titanium sheet metal is used for the skin in some aircraft, although aluminum is used where demands are less intense. It is more common to see titanium used for the skin in fighter craft and aluminum used for commercial aircraft. Engineering is as important as the material used, and composite construction is used to achieve the perfect balance between strength and cost efficiency.