|
Seminar Presentations
Rapid Prototype Tooling
Indian Industry's Need of the Hour
(As presented at International Seminar
on World Class Tooling held in conjunction with DieMould India
'98 Exhibition organised by TAGMA.)
S. J. Bakshi, Protosys Technologies
Pvt. Ltd., Mumbai, India.
Abstract
We have to be innovative to
survive in today's competitive world. Innovations are expected
in every aspect of business viz. Finance, Production, HRD,
Technology etc. Product Development requires the essence of
innovation the most. A new product can help us to the same
old things differently and more effectively.
Most of the time, innovative
products have to be tried and tested to ascertain the desired
functionality and/or aesthetics. For this purpose, a prototype
is made. Today, the Rapid Prototyping technology permits us
to make a sample fast and easy. However quite often the prototypes
are required in limited quantities viz. 5 to 10. Also, at
times the material limitation of the Rapid Prototyping Technologies
necessitates converting the sample into another material.
In such cases, Rapid Tooling
fir Prototypes is used. Traditionally, plaster moulds were
used for obtaining the negative impression of the part and
then the available materials were cast in them. The type of
parts that can be made had severe limitations. With the advancement
of various processing and material technologies when applied
in combination with Rapid Prototyping can not only overcome
these limitations but also give tools for limited production
in a very short time.
Various aspects of such techniques
with respect of the Indian Industry in general and the mold
and die industry in particular are discussed.
Why
Prototype ?
Advances in the field of Computer
Aided Design and Analysis have not reduced the importance
of a prototype. In fact, they have only eased the process
of making it. Visual verification / presentation, assembly
testing and functional testing with the help of a prototype
are still necessary before investing in production.
The overall business scenario
has resulted in lower margins and demand for variety in the
shortest possible time. Loss of business due to delay in time-to-market
is much higher than that due to cost over-run. Also it is
a well-established fact that the cost of change in the initial
stages is much lower than at any later stage. This necessitates
innovative designs and more investment at the early stages
so that overall profitability is higher at a later stage.
Need for prototype is different
in different situations. Hence the technique to develop it
should be considered accordingly. Various options are available
for building prototypes. They range from hand-made to more
sophisticated techniques that use computer based equipments.
In recent years, development
of layered manufacturing technology called Rapid Prototyping
(RP) has resulted in prototypes being made more easy and faster
than ever before and thus increased their demand as well.
Besides, being an additive process, it also eases out the
manufacturing of complex parts vis-à-vis the traditional
material removal processes.
When compared with the machining
process, the present state of this technology has a few limitations
on the parts that can be manufactured. The major ones being
size, material, finish and cost per piece. However, the greatest
advantage this technology offers is the translation of an
idea into a physical model in a very short time.
To overcome the material limitations
of RP, there are a number of secondary operations wherein
the dies or molds are made quickly. Such processes are called
Rapid Prototype Tooling (RPT). In some cases the RP part is
used as a master pattern and in some, the RP process builds
the tool.
Prototype
Tooling Options
A variety of methods for development
of cast tools quickly are traditionally available. Plaster
& Rubber Molding are an example. Of late, Silicone Rubber
Molding, Investment Casting from RP parts, Direct tool building
from RP parts etc., have also been developed. These techniques
provide make development of tools for smaller components very
easy.
Silicone Rubber Molds being
flexible reduce the requirement of inserts and other moving
parts, whereas other techniques can give similar tools in
shorter time and reduced machining requirements.
The table below shows a broad
comparison of various tooling options available :
 |
| |
Lead
Time
|
Expected Quantity
|
Total
Cost
|
Cost Per Piece
|
Functional usability
|
Tolerances Achievable
|
 |
| RP
Models * |
A
|
E
|
B
|
B
|
C to E
|
B to E
|
|
| Rubber/Epoxy Tools |
B
|
D
|
A
|
D
|
C to E
|
C to E
|
|
| Spray Metal Tools |
C
|
C
|
C
|
C
|
B to D
|
B to D
|
|
| Direct Tool from RP |
B to C
|
B to C
|
B to C
|
B to C
|
A to B
|
B to C
|
|
| Cast Metal Tools |
B to C
|
C to D
|
B to C
|
B to C
|
A to B
|
A to B
|
|
| Low Cost Tools |
D
|
B
|
D
|
B
|
A to B
|
A to B
|
|
| Machining |
E
|
A
|
E
|
A
|
A
|
A
|
|
Rating A to E represent most
to least desirable property respectively.
Part
Selection
Selection of the right part
for the right process is also an important aspect in economic
justification of the RPT. A part that is fairly simple in
its shape and does not have too many features on it may prove
out to be economical by conventional process. Selection of
such parts can give misleading conclusions of the new technology.
If the right type of the part
is selected, it can even reduce the development time by more
than 30% and at cost approximately half the conventional methods.
The more complex the part, the more economical it could be.
The complexity could be in terms of number of features on
a part or its profile definition.
Technology
Trends
Direct Tooling from RP is also
fast developing and all RP system developers are working towards
improving accuracies, finish and material varieties. Epoxy
and Silicone Rubber manufacturers are improving on material
properties so that the tools can withstand the operating conditions
and yield a larger parts-per-tool ratio. Urethane manufacturers
are coming with properties equivalent to production materials.
High Speed Machining is considered
as an alternative to Rapid Prototyping and Tooling. However,
the economics are yet to be established. Besides the inherent
limitations of materials removal process will still remain.
Hence RPT for prototype manufacturing
appears to being useful and economical for the next five to
ten years. A combination of some of the RPT Options with the
High Speed machining could complement each other resulting
in better and faster tool.
Market
Trends
With increased competition and
fast paced developments, the only thing that is constant is
change. Everyone demands more for less in such situations,
the ones with better, cheaper and more variety can only survive.
Today, everyone talks about innovation. We also have example
of various countries/companies that have survived and grown
only because of their investments in R & D and innovation.
It is a proven fact that economics
turn favourable only on large production volumes. However,
it must also be noted that every innovation will have to be
tried ad tested critically before it is commercialised or
launched. Hence, on the other hand the industry will also
have to adapt to such low volume production for promoting
innovative product developments.
Indian manufacturing industry has
so far been thriving on production of already proven designs.
But we cannot remain followers forever and of late, a new
trend of local developments has been initiated. Hence, RPT
will be one of the key tools to quickly verify innovative
ideas.
World over, the prime industry
indicator used to be the automotive market. But now, it is
shifting to the consumer electronic & white goods. The
product life being shorter, the need for variety in this segment
is much larger. A big growth in this industry has also been
projected in the Indian market. The parts of such items being
smaller, RPT is an ideal fit for this segment too.
Implications
on the Mold & Die Industry
Some of the RPT processes reduce
the requirements of intricate inserts moving cores etc. but
still the basic concept of tool design has to be followed.
However, in the majority of RPT Options, the conventional
techniques of tool designing have to be followed. The conventional
tool sets are also required by these techniques.
RPT only offers an additional option
for quickly manufacturing of the main element of a tool. It
should also be considered that it gives time at the cost of
finish & accuracy as compared to the finish machining
processes.
Hence RPT is not a substitute for
conventional tool making process but a supplement to it and
should boost the interests of the tool - maker as well.
|
