Aluminum
General Characteristics
Aluminium is a relatively soft, durable, lightweight, ductile and malleable metal with appearance ranging from silvery to dull gray, depending on the surface roughness. It is nonmagnetic and does not easily ignite. Aluminium has about one-third the density and stiffness of steel. It is easily machined, cast, drawn and extruded. Aluminium is a good thermal and electrical conductor, having 59% the conductivity of copper, both thermal and electrical, while having only 30% of copper's density. Aluminium is capable of being a superconductor.
Corrosion resistance can be excellent due to a thin surface layer of aluminium oxide that forms when the metal is exposed to air, effectively preventing further oxidation. The strongest aluminium alloys are less corrosion resistant due to galvanic reactions with alloyed copper. This corrosion resistance is also often greatly reduced by aqueous salts, particularly in the presence of dissimilar metals.
Aluminum is often referred to as a “miracle metal” and for good reason. Its long list of inherent properties—lightweight, corrosion resistant, easily formed, highly conductive, highly reflective, non-toxic, durable and recyclable—gives manufacturers and designers a wide range of options for product innovation and process improvements. By virtue of its strength and beauty, aluminum is also the backbone and facade of noteworthy buildings worldwide.
The use of aluminum lowers energy costs and carbon emissions in dozens of applications. Recycled and lightweight aluminum packaging reduces shipping costs and emissions while an aluminum-intensive vehicle can achieve a 32 percent reduction in energy consumption over its lifetime.
Aluminum plays an ever-increasing role in bringing the world closer together. The transportation industry has long relied on aluminum’s light weight and durability to improve safety and increase fuel efficiency. Air and space travel would not be possible without aluminum, as even the Wright Brothers knew when selecting an aluminum engine for the first flight. And now the digital world is realizing the benefits of aluminum for both product design and manufacturing efficiency. The ubiquitous laptops, smart phones and tablets seen today are the latest showcase for the modern metal.
Aluminum’s recyclable and lightweight qualities are attracting new markets as well, such as consumer electronics.
There are basically two methods for producing aluminum. Primary production involves mining bauxite deposits from the earth and performing electrometallurgical processing to ultimately form aluminum. Secondary production makes new aluminum from recycled scrap product. From there, different processing methods and alloys are used to form aluminum into its desired shape, strength and density.
Casting, or pouring molten aluminum into a mold, is used for high-volume parts requiring minimal machining, such as automotive parts. Sheet rolling is used to make long flat pieces of aluminum often used in transportation applications such as cars, planes and trains and also in consumer packaging for cans and foil. When strength and precision are needed, aluminum can be forged using compressions and dies to produce parts such as racecar wheels. Extrusion is used to form longer, thinner pieces of aluminum called rod, bar or wire, often used in the building industry.
Uses and applications
For heavy industrial markets, aluminum brings a durable, strong, corrosion-resistant material that is also lightweight and easily formed. Transportation and aerospace companies can create innovative products without sacrificing safety or performance. In consumer applications, manufacturers value aluminum’s lightweight properties for reducing transportation costs and its visual appearance for creating appealing designs. Across all industries, aluminum’s infinite recyclability supports sustainable manufacturing and makes a positive contribution to the nation’s environmental goals.
Aluminum main applications are:
Automotive Industry and Transportation
When it comes to preferred materials for the manufacturing of new cars and trucks, an accelerated transition to strong, affordable and infinitely recyclable aluminum is well underway. That’s because the high strength, low weight metal can be designed to create passenger and commercial vehicles that are lighter – not necessarily smaller – so they go farther while using less fuel or battery power.
With increasing consumer, regulatory and environmental pressures, automakers are reimagining the automobile from the wheels up to take a more holistic approach to integrate innovative designs, next gen engines and power sources, cleaner fuels and advanced materials.
Aluminum is the rising material of choice, offering the fastest, safest, most environmentally-friendly and cost-effective way to boost fuel economy and cut total carbon emissions.
Aircraft & Aerospace
The advancement of aircraft and rocket technology is directly tied to the advancement and production of aluminum alloys. From the Wright brothers’ use of aluminum in the engine of their first biplane to NASA’s use of an aluminum-lithium alloy in the new Orion spacecraft-aluminum has created the potential for mankind to fly both around the Earth and into space.
The airframe of a typical modern commercial transport aircraft is 80 percent aluminum by weight. Aluminum alloys are the overwhelming choice for the fuselage, wing, and supporting structures of commercial airliners and military cargo/transport aircraft. Structural components of current United States Navy aircraft are made of fabricated wrought aluminum (forged, machined and assembled parts). Attention is now focused toward aluminum casting technology, which offers lower manufacturing costs, the ability to form complex shapes and the flexibility to incorporate innovative design concepts.
Ever since the launch of Sputnik a half-century ago, aluminum has been the material of choice for space structures of all types. Chosen for its light weight and its ability to withstand the stresses that occur during launch and operation in space, aluminum has been used on Apollo spacecraft, the Skylab, the space shuttles and the International Space Station. Aluminum alloys consistently exceed other metals in such areas as mechanical stability, dampening, thermal management and reduced weight.
Construction
Aluminum was first used in quantity for building and construction in the 1920s. The applications were primarily oriented toward decorative detailing and art deco structures.
Architects can design light structures with greater design flexibility. Aluminum's durability means it can serve its function in a building for many decades to reduce maintenance costs.
The breakthrough came in 1930, when major structures within the Empire State Building were built with aluminum (including interior structures and the famous spire). Aluminum's exceptionally high strenght-to-weight ratio makes it specially useful as a structural material, weighing up to 65% less than steel.
Today, aluminum is recognized as one of the most energy efficient and sustainable construction materials. Coated aluminum roofs can reflect up to 95% of sunlight, dramatically lowering energy consumption. The estimated recycled content of aluminum building materials used today is between 50 and 85 percent.
Aluminum's contributions to energy savings during the life cycle of buildings is equivalent to hundreds of millions of barrels of crude oil usage annualy.
Aluminum Cans
Since the firts uses of aluminum cans in 1959, there has been a steady growth in sodas, energy drinks, sparkling waters and increasingly, craft brew beers. Aluminum cans are the most sustainable beverage package and are infinitely recyclable. They chill quickly, provide a superior metal canvas to print on and, perhaps most importantly, protect the flavor and integrity of our favorite beverages.
As the most valuable package in the bin, aluminum cans are, by far, the most recycled beverage container. The average can contains 70 percent recycled metal.
Aluminum cans are lightweight and easily stacked. This provides storage and shipping efficiencies and limits overall transportation carbon emissions through logistics and supply chains.
On average, a recycled aluminum can becomes a new can in less than 60 days. Beverage containers can be infinitely recycled in a continuous closed loop.
Aluminum cans provide long-term food quality preservation benefits. Aluminum cans deliver 100 percent protection against oxygen, light, moisture and other contaminants. They do not rust, are resistant to corrosion and provide one of the longest shelf lives of any type of packaging. Aluminum-based food canning has an unparalleled safety record. Tamper-resistant and tamper-evident packaging provides consumers with peace of mind that their products have been safely prepared and delivered. A vast variety of products are packaged using aluminum in addition to food and beverages: aerosol products, paint and thousands of other items in the consumer products market.
Foil & Packaging
Aluminum foil is produced by rolling sheet ingots cast from molten billet aluminum, then re-rolling the sheets to the desired thickness. To maintain a constant thickness, beta radiation is passed through the foil. Sensors on the far side sense the radiation levels and adjust the rollers to apply more or less pressure. Foil can also be produced by continuously casting and cold rolling. Aluminum foil provides a complete barrier to light, oxygen, moisture and bacteria. For this reason, foil is used extensively in food and pharmaceutical packaging. It is also used to make aseptic packaging that enables storage of perishable goods without refrigeration.
Packaging foil is now divided into three major categories: household/institutional foil, semi-rigid foil containers and flexible packaging. For decades, the use of foil has grown steadily in each of these categories:
Food Preparation: Aluminum foil is “dual-ovenable” and can be used in both convection and fan-assisted ovens. A popular use of foil is to cover thinner sections of poultry and meat to prevent overcooking.
Insulation: Aluminum foil is 88 percent reflective and is widely used for thermal insulation, heat exchanges and cable liners. Foil-backed building insulation not only reflects heat, aluminum sheet also provides a protective vapor barrier.
Electronics: Foil in electrical capacitors provides compact storage for electric charges. If the foil surface is treated, the oxide coating works as an insulator. Aluminum foil capacitors are commonly found in electrical equipment, including television sets and computers.
Geochemical Sampling: Aluminum foil is used by geochemists to protect rock samples. Foil provides a seal from organic solvents and does not taint the samples as they are transported from the field to the lab.
Art and Decoration: Anodizing aluminum foil creates an oxide layer on the aluminum surface that can accept colored dyes or metallic salts. Through this technique, aluminum is used to create inexpensive, brightly colored foils.
Recycling
Aluminum producers and recyclers in the aluminum industry work with individuals, communities and businesses to enable both curbside and industrial recycling programs. UBC (used beverage container) recycling is the most readily recognized of the recycling programs. Aluminum is also recycled at the end of life from products such as cars and building parts. Window frames, wire, tubing and electronics are additional examples of aluminum that is recycled at the end of life.
Infinitely recyclable and highly durable, nearly 75 percent of all aluminum ever produced is still in use today. Aluminum is 100 percent recyclable and retains its properties indefinitely.
Demand for aluminum continues to skyrocket and recycling aluminum saves more than 90 percent of the energy required versus producing new metal.
Aluminum creates competitive advantages for the companies that use the world’s most sustainable metal. For example, in the packaging industry, aluminum cans attract consumer goodwill. Their ease of use, safety, convenience, light weight, and durability make them a favorite in homes across the country. Curbside and community recycling programs highlight the metal’s value in the recycling bin. Aluminum cans provide a printable surface that effectively accepts coatings and paint—a key advantage for brand identification and attractiveness of packaging. The benefits of aluminum work in both directions—both consumers and industry win.
Once the scrap is collected and sorted, it is placed into a melting furnace and turned into molten aluminum at temperatures ranging from 1300 to 1400 degrees Fahrenheit. This molten aluminum may be kept in its liquid state or cast into large slabs called ingots or billets. In some cases, alloying elements are added to the liquid aluminum in order to produce the desired metal for a specific product type. Aluminum ingots may be rolled back into a sheet product (like can or auto body sheet) while billets can be extruded into a shaped product, such as window frames or a computer case.
High performing products such as building materials or automotive parts can be recycled from other high quality aluminum products, such as aircraft components. And since aluminum never loses its performance or strength during the recycling process, the same piece of aluminum can enter the secondary production process time and time again, multiplying the cost savings and environmental benefits.
