Rapid prototyping is a technique used to quickly fabricate a scale model of a physical part or assembly using 3D computer-aided design (CAD) data and 3D printing technology. It originated in the late 1980s and allows for the production of models and prototype parts to test designs. Reverse engineering involves analyzing an existing system to recreate its components, while reengineering is a radical redesign not constrained by previous solutions. Concurrent engineering is an approach where design, manufacturing, and other functions integrate tasks concurrently to reduce time to market for new products.

1. RAPID PROTOTYPING:
Rapid Prototyping is a group of techniques used to quickly fabricate a scale model of a physical part
or assembly using three-dimensional computer aided design (CAD) data. Construction of the part or
assembly is usually done using 3D printing technology. The first techniques for rapid prototyping
became available in the late 1980s and were used to produce models and prototype parts.
History:
One such report was the 1997 Rapid Prototyping in Europe and Japan Panel Report
[2]
in which
Joseph J. Beaman
[5]
founder of DTM Corporation [DTM RapidTool pictured] provides a historical
perspective : The roots of rapid prototyping technology can be traced to practices in topography and
photosculpture. Within TOPOGRAPHY Blanther (1892) suggested a layered method for making a
mold for raised relief paper topographical maps .The process involved cutting the contour lines on a
series of plates which were then stacked. Matsubara (1974) of Mitsubishi proposed a topographical
process with a photo-hardening photopolymer resin to form thin layers stacked to make a casting
mold. PHOTOSCULPTURE was a 19th-century technique to create exact three-dimensional replicas
of objects. Most famously Francois Willeme (1860) placed 24 cameras in a circular array and
simultaneously photographed an object.The silhouette of each photograph was then used to carve a
replica. Morioka (1935, 1944) developed a hybrid photosculpture and topographic process using
structured light to photographically create contour lines of an object.The lines could then be
developed into sheets and cut and stacked, or projected onto stock material for carving. The
Munz(1956) Process reproduced a three-dimensional image of an object by selectively exposing,
layer by layer, a photo emulsion on a lowering piston. After fixing, a solid transparent cylinder contains
an image of the object.
The technologies referred to as Solid Freeform Fabrication are what we recognize today as Rapid
Prototyping, 3D Printing or Additive Manufacturing : Swainson (1977), Schwerzel (1984) Worked on
polymerization of a photosensitive polymer at the intersection of two computer controlled laser beams.
Ciraud (1972)Considered magnetostatic or electrostatic deposition with electron beam, laser or
plasma for sintered surface cladding. These were all proposed but it is unknown if working machines
were built. Hideo Kodama of Nagoya Municipal Industrial Research Institute was the first to publish an
account of a solid model fabricated using a photopolymer rapid prototyping system (1981).
[2]
Even at
that early date the technology was seen as having a place in manufacturing practice. A low resolution,
low strength output had value in design verification, mould making, production jigs and other areas.
Applications: http://www.slideshare.net/malikusman/rapid-prototyping-and-its-applications

2. Advantages:
The Prototype gives the user a fair idea about the final look of the product.
Rapid prototyping can enhance the early visibility.
It is easier to find the design flaws in the early developmental stages.
Active participation among the users and producer is encouraged by rapid
prototyping.
As the development costs are reduced, Rapid prototyping proves to be cost
effective.
The user can get a higher output.
The deficiencies in the earlier prototypes can be detected and rectified in time.
The speed of system development is increased. It is possible to get immediate
feedback from the user.
There is better communication between the user and designer as the requirements
and expectations are expressed in the beginning itself.
High quality product is easily delivered by way of Rapid prototyping.
Rapid prototyping enables development time and costs.
There are many innovative ways in which Rapid prototyping can be used.
DISADVANTAGES:
Some people are of the opinion that rapid prototyping is not effective because, in
actual, it fails in replication of the real product or system.
It could so happen that some important developmental steps could be omitted to
get a quick and cheap working model. This can be one of the greatest
disadvantages of rapid prototyping.
Another disadvantage of rapid prototyping is one in which many problems are
overlooked resulting in endless rectifications and revisions.
One more disadvantage of rapid prototyping is that it may not be suitable for large
sized applications.
Reverse and Re-Engineering
Reverse Engineering:
A method of recreating software system components for which the source code is missing,
out of date, or is otherwise not in agreement with existing components. Disassembles and
decompilers are examples of Reverse engineering tools.
.www.users.qwest.net/~dssecor/y2k_glos.html
The process of analyzing an existing system to identify its components and their inter
relations interrelationships, and to create representations of the system in another form or at a
higher level of abstraction .

3. Advantages:
* High degree of Precision for wide range of surfaces as compared
to manual measurements
* Quicker turnaround time as compared to conventional methods
* Reproduce existing machine part or object efficiently & cost-
effectively
* Faster time-to-market for your products
Re-Engineering:
Reanalysis and radical redesign that is not bound by previous obsolete solutions. (Contrast
TQM - incremental improvement)
Coined by management guru Michael Hammer, it's a quality improvement tool: start from
scratch, question assumptions, and radically redesign what people do and how they work.
Reengineering Benefits
Lower costs. Evidence from a number of US projects suggests that reengineering an
existing system costs significantly less than new system development. Ulrich, for example
reports on a reengineering project that cost $12 million, compared to estimated
redevelopment costs of $50 million.
Lower risks. Reengineering is based on incremental improvement of systems, rather than
radical system replacement. The risk of losing critical business knowledge, which may be
embedded in a legacy system, or of producing a system that does not meet its users’ real
needs, is drastically reduced.
Better use of existing staff. Existing staff expertise can be maintained, and extended
accommodate new skills during reengineering. The incremental nature of reengineering
means that existing staff skills can evolve as the system evolves. The approach carries less
risk and expense which is associated with hiring new staff.
Revelation of business rules. As a system is reengineered, business rules that are
embedded in the system are rediscovered. This is particularly true where the rules govern
exceptional situations.
Incremental development. Reengineering can be carried out in stages, as budget and
resources are available. The operational organisation always has a working system, and end
users are able to gradually adapt to the reengineered as it is delivered in increments.
www.trillium.org/glos_med.html

4. Concurrent engineering
Concurrent engineering is a work methodology based on the parallelization of tasks (i.e.
performing tasks concurrently). It refers to an approach used in product development in
which functions of design engineering, manufacturing engineering and other functions are
integrated to reduce the elapsed time required to bring a new product to the market.
Concurrent Engineering (CE) is a systematic approach to integrated product development that
emphasizes the response to customer expectations. It embodies team values of co-operation,
trust and sharing in such a manner that decision making is by consensus, involving all
perspectives in parallel, from the beginning of the product life cycle
Advantages:
Manufacturing Personnel are able to identify production capabilities and capacities .They have thus the
opportunity to inform the design group about the suitability of certain materials on the flipsides the
designer would know the suitability of certain designs in aiding in cost reduction and quality improvement
in production/assembly process.
Early opportunities for design or procurement of critical tooling, some of which might have long lead
times. early consideration of the Technical Feasibility of a particular design or a portion
of a design. Again this can avoid serious problems during production.
Disadvantages of concurrent design[edit]
Concurrent design creates its own issues, such as the implementation of early design reviews, the
dependency on efficient communication between engineers and teams, software compatibility, and
opening up the design process.[9]
A concurrent design process usually requires that computer models
(computer aided design, finite element analysis) are exchanged efficiently, something that can be
difficult in practice. If such issues are not addressed properly, concurrent design may not work
effectively.