Using Rapid Prototyping.
S. J. Bakshi, Protosys Technologies Pvt. Ltd., Mumbai, India.
As presented at
"Competitive Design Management" module on "Achieving
Competitive Excellence" management programme conducted
by Warwick Manufacturing Group (U.K.) & Confederation
of Indian Industry (CII) Mumbai.
To highlight the use of Rapid
Prototyping techniques in the Design Validation process for
In the modern times when
technology developments are the key to success and survival
of any business, design is gaining more emphasis than ever
before. It has been a traditionally known fact that "a
product can only be as good as its design". It is also
worth noting, "a design can only be as good as its specifications".
Design Validation is a process that enables us to confirm
that the design is in accordance with its specifications.
As the specifications vary from product-to-product and application-to-application,
processes too vary vastly e.g. Validation process for Mechanical,
Civil, Electrical, Electronic or software product will differ
from each other; similarly, the specifications of a building
in Mumbai will differ from that in the Gulf or the Arctic
region. Thus Design Validation is a very generic term used
to ensure the conformance of the design for its end purpose.
Mechanical Product Design
The validation of designs of mechanical
products can be broadly classified into the Form, Fit &
Function categories. These have to be applied to each individual
component that goes into the product and also to the product
as a whole. As these processes have to be undertaken before
the production stage, they need a model. Traditionally, the
models were physical, sketched or mathematical.
Then, the early 1980's saw the
evolution of Information Technology (IT) era and thus computational
intensive techniques like Finite Elements, Kinematics and
Tolerance Charting became easy to implement. Further advancements
in the IT arena saw development of Computer-Aided-Design softwares.
These evolved from simple 2D drafting to 3D modeling to assembly
modeling to parametric & feature based modeling. These
eased out many of the validation processes e.g. visualization,
interference checking, dimensional inter-relations etc.
All these digital methods
of validation enabled more alternatives to be tried for the
same concept and thus have proven their worth. However, the
physical world still has its own advantages in terms of the
feel-of-the design. If a picture is worth a thousand words,
then a prototype is worth a thousand sketches. Hence, the
importance of physical model was always maintained.
Cost incurred on a product development
project increase drastically once the prototype stage is completed
and the product is taken for production. The cost involved
in implementing a change at a stage thereafter is also goes
on increasing steeply. A study conducted by Mckinsey &
Co shows that the cost overrun by 50% only affects the profitability
by 3.5% whereas a delay in the launch of the product affects
it by nearly 33%.
Thus it is important that the product
development has to be fast and at the same time ensuring it
is in conformance with the original specifications. It may
be worth spending more during this stage than having to spend
many folds higher later.
Until early 1980s, the IT developments
had already speeded up most of the other stages of the product
development cycle. However, the conventional methods of making
a physical prototype were either manual or by machining. These
are either not accurate or take a long time.
In 1982, the technology of Rapid
Prototyping (RP) was first established in the US and process
for speeding up the prototype making was patented and commercialized
in 1985. It was called Stereo-lithography. The basic concept
of this technology is to build the part layer-by-layer. Over
the next decade, many other processes got patented all over
the world e.g. Fused Deposition Modeling, Laminated Object
Manufacturing, Selective Laser Sintering etc.
Growth in RP also saw the use of
RP parts being used as patterns for various casting applications
which give fully solid parts in materials that are equivalent
various engineering plastics or at times, even metals. Any
tooling process that uses RP at any of its stages is known
as Rapid Tooling process and similarly Rapid Manufacturing.
With a physical prototype in hand
visual validation becomes extremely easy. It also facilitates
the fitment checking in many cases and limited functional
trials can also be conducted with most of the parts that are
made using Rapid Prototyping, Tooling and Manufacturing processes.
These techniques are extremely
fast and the equipment is so versatile that it has almost
zero setup time for change of parts. Smaller parts having
high complexity in terms of shape and orientation of features
are very economical by these processes when compared to conventional
literature and case
studies highlight the benefits of Rapid
Prototyped parts for validating various aspects of mechanical