Primer on Aluminium
So what is aluminium?
Aluminium in colour is a silvery white to dull gray, (depending on the surface roughness) ductile member of the poor metal group of chemical elements and has the symbol Al. It is a soft, lightweight and malleable metal that is nontoxic, nonmagnetic, and nonsparking. It is also insoluble in alcohol, though it can be soluble in water only in certain forms. It is not soluble in water under normal circumstances and its atomic number is 13. Aluminium is the most abundant metal in the Earth's crust, and the third most abundant element overall, after oxygen and silicon. It makes up about 8% by weight of the Earth's solid surface but is too reactive chemically to occur in nature as the free metal. Instead, it is found combined in over 270 different minerals including clay, bauxite, mica, feldspar, alum, cryolite, and the several forms of aluminium oxide (alumina) such as emery, corundum, sapphire, and ruby. Aluminium is remarkable for its ability to resist corrosion (due to the phenomenon of passivation) and it is light weight. The yield strength of pure aluminium is 7-11 MPa, while aluminium alloys have yield strengths ranging from 200 MPa to 600 MPa. Aluminium has about one-third the density and stiffness of steel yet it is ductile, and easily machined, cast, and importantly in this piece is easily extruded. The chief source of aluminium is bauxite ore. Structural components made from aluminium and its alloys are vital to the aerospace industry and as we will find out are very important in other areas of transportation and building.
Aluminium is easily extruded but what is Extrusion and how was it invented?
Extrusion is a manufacturing process used to create long profiles, shapes, of a fixed cross-sectional profile. A material, often in the form of a cylindrical billet, is pushed and/or drawn through a die of the desired profile shape. Hollow sections are usually extruded by placing a pin or piercing mandrel inside of the die and in some cases positive pressure is applied to the internal cavities through the pin. Some materials are hot drawn while others may be cold drawn and extrusion may be continuous (producing indefinitely long material) or semi-continuous (producing many short pieces.)
The feedstock may be forced through the die by various methods. A single or twin screw auger, powered by an electric motor, or a ram, driven by hydraulic pressure (for steel alloys and titanium alloys for example), oil pressure (for aluminium) or in other specialized processes such as rollers inside a perforated drum for the production of many simultaneous streams of material. Extrusion simulation tools help to understand the extrusion process and to optimize development of tools and products. Extrusion is also the first step in the process of extrusion and spheronization, a commonly used process in the pharmaceutical industry. Commonly extruded materials include metals, (such as aluminium) polymers, ceramics, and foodstuffs and metal extrusion are used by industry for various purposes such as: copper pipe for plumbing and aluminium extrusion profiles for tracks, frames, rails, and mullions.
Commonly seen as the inventors or founders of aluminum extrusion, were the Cowles brothers of Ohio. They owned the Electric Smelting and Aluminum Company, founded as Cowles Electric Smelting and Aluminum Company, and Cowles Syndicate Company, Limited in the United States and England during the mid-1880s to extract and supply valuable metals. The Cowles companies are remembered for producing alloys in quantity sufficient for commerce. Their furnaces were electric arc smelters, one of the first viable methods for extracting metals.
Present day extruded tube is used for trusses that link together the International Space Station (ISS). A wonder of science and aerospace engineering, this vast ISS program is truly thriving thanks to the diversity aluminium extrusions afford. Since the stations launch in 1998 12 major components have been built in space with Boeing Company engineers working with extrusions on an enormous scale during construction and assembly of the most up-to-date extruded truss sections. Aluminium extruded tubing is used in much of the truss structures, including a dozen outboard and inboard truss sections designed by Boeing engineering teams in Canoga Park and Huntington Beach, California. These extruded aluminium outboard truss sections house the U.S. power generation and distribution system. Four outboard truss sections house power generation modules, with two sections providing power from the superstructure's port side, and two from the starboard side. The concluding ISS integrated truss configuration will measure 361 feet end-to-end, with its solar arrays feeding the station's electrical power generation system. This comprises roughly one acre of solar collection, providing more than 80 kw of power. ISS construction is slated for completion in 2010. Boeings Karl Wefers sums up, "aluminium extrusions will always be considered for future structures in space, because the extruded aluminium's mechanical and optical properties are so ideally suited to space applications." Aluminium extrusion is also being used innovatively much closer to home.
The introduction of the Ford GT concept car at Ford's centennial celebration in 2003, was followed by its production line debut as Ford's flagship brand in 2004. But why is this interesting to us? Well, Ford design engineers have raised aluminium technologies to a new threshold. Ford's design team, working closely with extrusions, have developed an all-new extruded aluminum space frame as the foundation of its legendary redesigned and re-engineered 2005 Ford GT. The supercharged MOD 5.4-liter V-8 engine produces 550 horsepower and 500 foot-pounds of torque. Ford's "dream team" of designers and engineers are pioneering advanced technology for the GT program. The new GT, though it has every bit of its namesake's smooth, racy look, features an aluminum extruded space frame. The aluminium chassis, unheard of in the GT's heyday in the 1960s, uses extrusions to connect four corner castings to one behind the passenger compartment, creating a rigid, strong and lightweight welded frame. To meet performance targets for static and dynamic body stiffness, the team created new joining and assembling technologies, and developed an industry-first aluminum shim-nut system to attach and locate body panels in proper position relative to the extruded space frame.
The aluminum space frame chassis includes: 35 extrusions, 30 of which were developed for Ford; multiple stamped aluminum panels; five complex castings; and four semi-solid formed castings, which anchor the corners and serve as mounting points for a double wishbone suspension. The chassis features unequal-length extruded control arms and coil-over spring-damper units to accommodate its low profile. In addition, bolt-on extrusions structurally support the engine compartment and are integrated into the bumper assembly. The rear sport bar is also extruded aluminum. Huibert Mees, Ford GT Chassis Systems Supervisor points out the key role aluminum extrusions play in bringing the GT phenomenon back to the road: "Extrusions are easily integrated into the vehicle's visual design. Many of the extrusions are designed with visual details that enhance the car's aggressive appearance. Many of the aluminum extrusions are seen in the passenger compartment and through the rear deck."
This use of aluminum extrusions is now widespread throughout the automotive industry with Audi, Honda, BMW and Mercedes all incorporating the outstanding weight to strength ratio aluminum provides, combined with the flexibility that extrusion offers in design terms.
Simmal are a leading UK supplier of aluminium extrusions and the informed choice of many major manufacturing, engineering and building companies throughout the world. Simmal aluminum extrusion solutions are implemented throughout every market sector, from consumer goods to engineering, every aspect of your life will come in to contact with a Simmal product. Our unrivalled expertise and proven pedigree in aluminum extrusions stretches back over four decades and currently amounts to over 500 years of accumulated knowledge across 50 plus employees. This passion and commitment for staying at the forefront of aluminum extrusion technology is why so many of our customers don't just make Simmal their first choice, but their only choice. Examples of this range from Medical - from simple aluminum trunking systems to critical applications in intensive care. Office furniture - from the design of turnkey aluminum extruded solutions to the manufacture, supply kitting and assembly of workstations and screening systems. Automotive - from safety critical aluminum extrusions for braking applications to high tech, high spec, high visibility dashboard components. Building - toilet cubicles, roofing systems, partitioning, showers and retail. Last but not least is Leisure - from TV legs to tent pegs and street signs to Venetian blinds, our foot print is all around.
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