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Aluminum fabrication is the process of shaping aluminum into a finished product, such as a solar panel part or an outdoor enclosure. Fabrication of aluminum spans a wide field of processes, including welding, stamping, bending, extruding, and shearing, just to name a few. In this article, we're giving a basic overview of aluminum fabrication, from properties to fabrication techniques to industries and applications.
Aluminum has been used in mass production only for the last hundred or so years. Before that it was as rare and valuable as gold, since the highly malleable metal was extremely rare in its free (metal) form. Aluminum’s mass production can be attributed to the Hall-Héroult process for extracting aluminum, patented in 1886, which is still used today.
The aluminum manufacturing process starts with the mining of bauxite, with every four pounds of bauxite being refined into two pounds of alumina. The two pounds of alumina then must be further refined into a single pound of aluminum. To do this, alumina must be dissolved into a bath of molten cryolite, and an electric current passed through the bath using anodes. This draws oxygen atoms out of the alumina, leaving molten aluminum at the bottom of the pot. The refined aluminum is then siphoned out and put in a holding furnace, from which it can be cast into an ingot and sent to be formed into bar, wire, sheet, or other forms. The electrolytic process, however, is still far more expensive than recycling, which requires only a fraction of the energy. This is one of the main reasons aluminum recycling is so useful and important.
In general, aluminum as a fabrication material is quick and easy to shape, thanks to its softness and lightness. Its properties can change, however, depending on how it is combined with other metals to create alloys.
Aluminum is a popular material for its unique combination of properties. At a third the weight of stainless steel, it’s a lightweight metal with a higher strength-to-weight ratio. Aluminum is also an easy metal to work with thanks to its comparative softness, corrosion resistance, and recyclability. Its non-toxicity has made it a popular choice for food preparation machinery, and its reflective and non-combustive properties have also cemented its place in lighting.
At the same time, this softness and weakness compared to stainless steel can make for less sturdy end products. Thanks to its thermal conductivity, many types of aluminum can also be difficult to weld for the inexperienced because it can easily be melted through. Certain stresses can also cause aluminum to break, as it can be brittle in some ways from manufacturing processes.
Extrusions put the least stress on aluminum. Extrusion forces a piece of aluminum through or around a die, which can be open or closed. This forces the metal to conform to the size and shape of the die. Extrusions can be done either hot (where the metal is heated) or cold (where the metal is room temperature).
Drawing pulls metal through a tapered die to stretch it, with deep drawing referring to a resulting product with a greater or equal depth than its width. Aluminum is often drawn into wire and products like cans, thanks to its ductility. This is especially useful for the 3003, 5005, and 5052 alloys.
Forming, including bending, stamping, and rolling, suits aluminum’s flexibility and softness. The 3003 alloy is especially good for this, as well as the 5052 and 6061 varieties, but most alloys in the 1xxx, 2xxx, 4xxx, 5xxx, and 8xxx alloy families can be formed. Forming involves pressing part or all of a sheet or plate to shape it into the desired end product.
Castings are made when liquid metal is poured into a mold or die. They’re best made from 4xxx and 5xxx alloys, which are known for their strength and wear resistance.
Forging, when metal is beaten or compressed into shape, is best for applications where the end results must be incredibly durable (such as for stress bearing parts).
Machining, including turning and milling, is best accomplished with 1100, 2011, 3001, and 6061 aluminum. Machining is a subtractive cutting process that sculpts by removing metal. With aluminum, it’s important to use special tools and lubricant, since the metal has specific thermal properties that make it difficult to use general equipment.
Waterjet cutting, the high pressure spraying of water with abrasives, does not use heat. In this way it avoids altering aluminum’s properties the way laser cutting could. However, aluminum can still also be cut by saw blade, laser, or plasma cutting.
MIG and TIG welding, which involve melting a metal thread to bind two pieces of aluminum together, are best performed on the 1xxx and 3xxx-6xxx aluminum alloys. Friction welding can also help when attaching aluminum to another metal.
Adhesive bonding is also a common method of assembling aluminum, as certain adhesives bond to the outer layer of aluminum oxide.
Aluminum’s properties make it ideal for uses that vary widely across industrial, commercial, and consumer applications, including:
Aerospace, which uses aluminum’s weight-to-strength ratio and corrosion resistance for wings, fuselages, and parts.
Packaging, including cans and foil, which rely on aluminum’s easy workability, softness, and durability.
Automotive applications, which use aluminum to absorb crash forces. It is also used to make car bodies and components lighter and therefore more fuel efficient.
Construction, where aluminum acts both as decoration and as structural material thanks to its energy efficiency and sustainability.
Electronics and electrical applications. Power grids use aluminum wiring and conductors in power grids. Consumer electronics like refrigerators and laptops use the metal thanks to its thermal abilities, light weight, and structural strength.
