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The qualities inherent in extruded aluminum profiles
offer freedom, versatility, and reliability to designers and engineers
in all market sectors, from building and construction to transportation
to engineered products, such as consumer goods. Numerous features
and benefits that satisfy a range of performance criteria are unmatched
by other materials and processes, including time- and cost-efficiencies
and process repeatability. See a materials
comparison chart showing properties of extruded aluminum and
how it performs against competing materials.
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Aluminum's Material Advantages
Corrosion-Resistant
Cryogenically Strong
Durable
Electrically Conductive
Formable
High Strength-to-Weight Ratio
Lightweight
Noncombustible
Nonmagnetic
Nonsparking
Nontoxic
Recyclable
Reflective
Resilient
Strong
Thermally Conductive
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Aluminum Extrusion's
Process Advantages
Attractive
Complex Integral Shapes
Cost-Effective
Design Flexibility
Ease of Fastening and Assembly
Ease of Fabrication
Low Tooling Costs
Machinable
Precision Tolerances Available
Rapid Prototyping
Short Lead Times
Versatility in Joining
Virtually Seamless
Wide Range of Finishes |
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The aluminum extrusion process really begins
with the design process, for it is the design of the product--based
on its intended use--that determines many of the ultimate production
parameters. Questions regarding machinability, finishing, and environment
of use will lead to the choice of alloy to be extruded. The function
of the profile will determine the design of its form and, hence,
the design of the die that shapes it.
Once the design questions have been answered, the
actual extrusion process begins with billet, the aluminum
material from which profiles are extruded. The billet must be softened
by heat prior to extrusion. The heated billet is placed into the
extrusion press, a powerful hydraulic device wherein a ram pushes
a dummy block that forces the softened metal through a precision
opening, known as a die, to produce the desired shape.
That is a simplified description of the process known
as direct extrusion, which is the most common method in use today.
Indirect extrusion is a similar process, but with some important
differences. In the direct extrusion process, the die is stationary
and the ram forces the alloy through the opening in the die. In
the indirect process, the die is contained within the hollow ram,
which moves into the stationary billet from one end, forcing the
metal to flow into the ram, acquiring the shape of the die as it
does so.
The extrusion process has been likened to squeezing
toothpaste out of a tube. When pressure is applied at the closed
end, the paste is forced to flow through the open end, accepting
the round shape of the opening as it emerges. If the opening is
flattened, the paste will emerge as a flat ribbon. Complex shapes
can be produced by complex openings. Bakers, for example, use a
collection of shaped nozzles to decorate cakes with fancy bands
of icing. They’re producing extruded shapes.
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