February 25, 2021
Aluminum apex of Washington Monument showing inscriptions on its east and north faces (source)
From planes and trains to the cellphone in your hand and the versatile roll of foil in your pantry, aluminum is omnipresent in today’s fabricated world. Which should come as no surprise, considering it is the most abundant metal in Earth’s crust. Yet, it is hard to imagine that aluminum was once prized more than gold! In fact, despite its abundance, aluminum was valued so highly in the 19th century because it was so difficult to obtain. It was so special, indeed, that in 1884 this rare “metal of kings” earned a prestigious perch atop the Washington monument in the shape of a cast pyramid.
Once scientists devised a feasible technique to extract large quantities of aluminum from bauxite (aluminum ore), the metal lost its scarcity-induced glory. However, its remarkable properties and abundant supply gradually made aluminum all-pervasive in commercial and residential environments.
Alloyed, as needed, with other metals, it is as light as it is strong, easy to shape, and it is reflective. Aluminum is also one hundred percent recyclable, non-toxic, and non-corrosive—all favorable qualities in an age when industrial waste poses a grave threat to our ecosystem. Thus aluminum is becoming, more and more, the material of choice in construction, transportation, common-use kitchen implements, and even in aluminum-based art installations around the world.
But it is one thing to extract aluminum from rocks; once you have the pure stuff at hand, however, now what do you do with it? Well, that depends on the end-use. Most aluminum products today are actually aluminum alloys, each one chemically designed to enhance the natural properties of pure aluminum.
But once the alloy has been formulated, it can undergo a number of processes to give it the desired shape for its intended purpose. Processing methods include forming, cutting, welding, extrusion, casting, and forging, among others.
Forming involves the use of force to bend and stretch aluminum sheets using techniques like spinning, deep-drawing, stretch forming, bending, and roll-forming.
Shearing and non-shearing methods are used to separate and cut large sheets of aluminum of various thicknesses into templated shapes. Shearing involves blanking and punching to cut sheet metal, while non-shearing techniques employ water jets, plasma, or lasers to get the job done.
Fabricators employ several methods to bond and assemble pieces of aluminum into a particular product. The last stage is painting or using abrasive blasting to provide the smooth finishing touches.
Extrusion is a widely used process that facilitates versatile possibilities in product design. The extrusion process involves channeling the product through a shaped die. This is a relatively inexpensive and quick method that allows manufacturers to create and test various prototypes in a short span of time. This, in turn, facilitates a quick production cycle for manufacturers.
T-slot extrusions are game-changers in that they permit easy design alterations without welding. Think Lego blocks with the ends shaped like the letter T. T-slot extrusions are lightweight, rust-resistant, and sturdy in any weather (aluminum gets stronger as the mercury drops!). You can shuffle the pieces using angle connectors to create easy-to-assemble aluminum solutions such as shelves, workbenches, tradeshow booths, aquarium stands, etc.
Casting is an inexpensive method of forming aluminum into a variety of shapes using sand molds. It is commonly used for large-scale projects like car engines. The aforementioned pyramidal cap atop the Washington Monument was made by casting.
This process involves the use of intense pressure to squeeze, press, and pummel metal. The three most common types of forging include open-die (for large components), closed-die (for intricate designs), and ring-rolled (for ring-shaped, high-strength uses). The end products are durable, lightweight parts commonly used in arenas that involve speed and energy efficiency.
Pigments and Powder
From sunscreen to solar panels to rocket fuel, aluminum powder has myriad applications. The powder is produced by melting the metal and spraying it under high pressure into powder form.
Rod and Bar
In this process, molten aluminum is elongated into circular or bar-shaped segments, usually through extrusion, rolling, coiling, or drawn directly from molten aluminum. Rod and bar are used to manufacture products like nuts and bolts, chain link fences, wires, and zippers. The colorful twist ties used for arts and crafts have pliant aluminum spines.
Sheet and Plate
Aircraft skins, food cans, and building façades (such as the Belfast Titanic Museum exterior shown at the top of this article) all begin as sheets and plates. The technique for making aluminum thinner and longer, like pasta sheets for lasagna, entails rolling the meatal under pressure.
With so many ways to process aluminum, is it any wonder that human ingenuity has found so many uses for this versatile metal? Our website features many practical and affordable examples!