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Since the dawn of civilization, mankind has been engaged in the
conception and manufacture of discrete products to serve the
functional needs of local customers and the tools (technology)
needed by other craftsmen. In fact, much of the progress in
civilization can be attributed to progress in discrete product
manufacture. The functionality of a discrete object depends on two
entities: form, and material composition. For instance, the
aesthetic appearance of a sculpture depends upon its form whereas
its durability depends upon the material composition. An ideal
manufacturing process is one that is able to automatically generate
any form (freeform) in any material. However, unfortunately, most
traditional manufacturing processes are severely constrained on all
these counts. There are three basic ways of creating form:
conservative, subtractive, and additive. In the first approach, we
take a material and apply the needed forces to deform it to the
required shape, without either adding or removing material, i. e. ,
we conserve material. Many industrial processes such as forging,
casting, sheet metal forming and extrusion emulate this approach. A
problem with many of these approaches is that they focus on form
generation without explicitly providing any means for controlling
material composition. In fact, even form is not created directly.
They merely duplicate the external form embedded in external
tooling such as dies and molds and the internal form embedded in
cores, etc. Till recently, we have had to resort to the
'subtractive' approach to create the form of the tooling.
Owing to the development and rapid spread of communication
technologies including the Internet, the world is indeed turning
into a global village. The rate of introduction of new products and
technologies is steadily rising. At the same time, pressures to
reduce time-to-market are mounting. Only companies that are able to
realize products rapidly are able to survive today.
From a technological viewpoint, rapid product realization involves
rapid design, rapid prototyping, and rapid tooling. Fortunately, a
class of technologies, also collectively called rapid prototyping
(RP) technologies, has emerged in the last two decades or so to
meet these requirements. Early technologies merely aimed to produce
single part look-alikes. However, intense R&D efforts are
taking place around the world to go beyond mere look alike' single
part prototyping, into functional, multi-part assemblies.
RP technologies are different from other modern manufacturing
technologies in many ways. In RP, material is usually added
incrementally in a layered manner and, occasionally, subtracted.
Some technologies depend upon layers of resin cured under the
influence of one or more CNC controlled laser beams. Others use
lasers to selectively sinter layers of powdered metal. There are
also RP technologies that do not use lasers at all. Indeed, RP is
turning out to be a potent arena for technological creativity.
This book provides an updated overview of RP technologies at a
level of detail that university engineering students taking courses
on RP as well R&D and operating professionals from industry
interested in RP are likely to find attractive. While the emphasis
is on laser-based technologies, other processesare also discussed.
With respect to each important RP process, the part/assembly
modeling techniques, the materials used, process itself, advantages
and disadvantages, accuracy and finish issues as well as
application potential are discussed.
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