What is
Rapid Prototyping?
(expanded)
The term Rapid Prototyping (RP) refers to a class
of technologies that can automatically construct
physical models from Computer-Aided Design (CAD)
data. These "three dimensional printers"
allow designers to quickly create tangible prototypes
of their designs, rather than just two-dimensional
pictures. Such models have numerous uses. They
make excellent visual aids for communicating ideas
with co-workers or customers. In addition, prototypes
can be used for design testing. For example, an
aerospace engineer might mount a model airfoil
in a wind tunnel to measure lift and drag forces.
Designers have always utilized prototypes; RP
allows them to be made faster and less expensively.
In addition to prototypes,
RP techniques can also be used to make tooling
(referred to as rapid tooling) and even production-quality
parts (rapid manufacturing). For small production
runs and complicated objects, rapid prototyping
is often the best manufacturing process available.
Of course, "rapid" is a relative term.
Most prototypes require from three to seventy-two
hours to build, depending on the size and complexity
of the object. This may seem slow, but it is
much faster than the weeks or months required
to make a prototype by traditional means such
as machining. These dramatic time savings allow
manufacturers to bring products to market faster
and more cheaply. In 1994, Pratt & Whitney
achieved "an order of magnitude [cost]
reduction [and] . . . time savings of 70 to
90 percent" by incorporating rapid prototyping
into their investment casting process.
At least six different rapid prototyping techniques
are commercially available, each with unique
strengths. Because RP technologies are being
increasingly used in non-prototyping applications,
the techniques are often collectively referred
to as solid free-form fabrication, computer
automated manufacturing, or layered manufacturing.
The latter term is particularly descriptive
of the manufacturing process used by all commercial
techniques.
A software package "slices" the CAD
model into a number of thin (~0.1 mm) layers,
which are then built up one atop another. Rapid
prototyping is an "additive" process,
combining layers of paper, wax, or plastic to
create a solid object. In contrast, most machining
processes (milling, drilling, grinding, etc.)
are "subtractive" processes that remove
material from a solid block. RP’s additive
nature allows it to create objects with complicated
internal features that cannot be manufactured
by other means.
Of course, rapid prototyping is not perfect.
Part volume is generally limited to 0.125 cubic
meters or less, depending on the RP machine.
Metal prototypes are difficult to make, though
this should change in the near future. For metal
parts, large production runs, or simple objects,
conventional manufacturing techniques are usually
more economical. These limitations aside, rapid
prototyping is a remarkable technology that
is revolutionizing the manufacturing process.
|
The term | Simple
