Rapid Prototyping - A Fast Track to
(as published in the Times of India dated 28 Feb.1997)
In a changing scenario of the
Indian industry, with multinationals bringing in their manufacturing
and R&D bases, technology that assists in development
of innovative products faster is a boon for the progressive
companies. Fastest time-to-market, quality and individual
customer satisfaction are the keys to successful market leadership.
Traditionally a prototype
is made for the purpose of verifying the form, fit and functional
aspects of the part or an assembly. This enables the designer
to be sufficiently confident of his design even before manufacturing
costly tools and also undertaking regular production. To develop
tooling for prototypes or regular production is a costly and
time consuming proposition. Besides, changes in the basic
design lead to re-working and at times scrapping of the entire
effort / material put in the development process.
Rapid Prototyping has reduced
this time-cycle drastically and added the element of accuracy
to it. Prototype samples generated by this process are also
useful in developing toolings by various casting and forming
processes. This on the whole has evolved the concept of Rapid
Over the period of time, companies
from various industrial sectors have taken great advantage
of this technology. Automotive, aerospace, medical implants
& instruments, toys, electronic goods, electrical switch
gear, consumer durables, furniture, packaging etc. are a few
of the segments thus covered.
General Motors, Chrysler, Ford,
Fiat, 3M, Kodak, Motorola, Apple Computers, Unilever, Gillette,
GE etc. are some of the beneficiaries around the world. In
India too, a few companies also been reported to have successfully
adopted this technology.
Rapid Manufacturing involves
3D CAD modelling, Rapid Prototyping, Rapid Tooling and Production.
3D CAD models can be generated using standard CAD softwares.
Almost all of these give an output in the form of a .STL file
which forms the input for the Rapid Prototyping system. Here
the data is sliced into multiple layers and then the model
is built layer-by-layer. It can be considered as a "3D
Rapid Prototyping concept was
first introduced as Stereolithography in the US around early
or mid-1980s. Since then, Fused Deposition Modelling, Laminated
Object Manufacturing, Selective Laser Sintering, Solid Ground
Curing, Direct Shell Production Casting, Inkjet Principle
etc. are some of the technologies on which different vendors
have developed their machines.
Prototypes built from most
of these technologies, are used for developing tools by way
of Investment Casting, Epoxy Molding, Silicone Rubber Molding,
Spray Metal Casting etc. These tools, if necessary, may also
be finished before being used for production. Variety of plastics
or metals can be produced depending upon the process followed
e.g. Injection Molding, Press / Vacuum Forming, Sand Casting,
Copy Milling, Spark Erosion, etc. Quantities upto a few thousand
pieces have been produced through some of these techniques.
Depending upon the stages chosen,
typical investments of the set-up range from 200,000 to 800,000
US Dollars. Service Bureaus charge somewhere in the range
of 40 to 100 US Dollars per hour of machine time. Around,
the world, the service bureaus have been used more widely
rather than captive facilities.
The seemingly higher cost can
easily be justified from the fact that the products which
used to take about six to eight months for development can
now be achieved within four to eight weeks with a possibility
of trying more alternatives. The intermediate Rapid Tools
can also be used for low volume production runs, which can
be useful for test marketing. Thus giving enough breathing
gap for manufacturing more durable conventional tools.
As in any other technology, Rapid
Prototyping also has its own limitations. Very fine intricate
details are difficult to obtain. Parts of very large sizes
have to be split into smaller pieces. Although parts of about
24 inches cube may be possible through this technology, 6
to 8 inch cube is considered to be the ideal size limit.
Considering all the factors,
rapid prototyping for the complex areas of the product and
conventional methods for the simpler areas should be judiciously
combined to achieve the optimum results.