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These
are primarily used to create multiple prototypes.
Rapid prototyping techniques are not economical
when more than one prototype needs to built
for the same component. In these cases different
rapid tooling techniques have been developed
to manufacture 25-30 prototypes, few hundred
to a few thousand prototypes and prototypes
in excess of 50000 pieces.
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| TECHNIQUES |
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| VACCUM
CASTING |
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In
this process moulds are made of silicon
rubber material. The process involves
making of the master pattern using
any available rapid prototyping techniques.
This pattern is then finished to the
quality in which final parts are required.
It is then suspended in an enclosed
box and liquid silicone rubber is
poured all around it. This sets with
time and becomes a solid rubbery mass
with the pattern inside. Now the mould
is cut along its parting line and
the pattern is removed from within.
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This
results in formation of the core and
cavity. Because the material is flexible,
undercut release is not a problem.
These
moulds are good enough for 25-30 pieces
in materials replicating properties
of thermoplastics.
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| EPOXY
TOOLING |
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This
process is similar to that of vacuum
casting. The only difference being
that instead if silicone rubber, the
material used is aluminum filled epoxy.
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Once
the mould is made from this material,
it can be put on a moulding machine
and components can be moulded in actual
material of choice. The mould life
normally is upto 200 pieces.
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| HYBRID
TOOLING |
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Tooling
is also made of different materials such
as ZAMAG which is an aluminum and zinc alloy.
Using this material in the above process
we can get components moulded in actual
material. The mould life is close to 1200
pieces.
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Depending
on the complexity, size and requirement
of the component, the right process has
to be chosen to arrive at a solution. Many
times, one particular process may not be
the solution, and several processes together
with conventional tooling methods are used
to arrive at a workable solution. This is
called Hybrid Tooling. We also make tools
by conventional tooling methods using aluminum
material for short run production.
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| DIRECT
METAL LASER SINTERING |
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In
this process, the material used is
an alloy of Nickel and Bronze. A Laser
beam is used to sinter the material
selectively to manufacture the core
and cavity inserts directly from CAD
data. This technique is a layer additive
technique for making the inserts.
These inserts after they have been
made on the machine can be directly
put on the moulding machine after
desired level of polishing.
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The
basic principle is that initially
the CAD data is sliced by the RP software
and then each slice layer is sintered
by the laser beam being deflected
in X-Y direction. After one layer
is complete, the build platform moves
down by a pre determined layer thickness
(usually 0.1mm) and then the second
layer is cured over it. This way the
entire prototype is built up by subsequent
joining of layers.
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The
advantage of this process is that it eliminates
the use of conventional CNC machining, EDM
and wire cut work from the process of manufacturing
complicated inserts. This process saves
time drastically over conventional techniques.
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The
tool life obtained from this technique is
comfortably 50000 pieces in ABS material.
All other thermoplastics can be processed
with the tool life depending on the abrasive
nature of the plastics material.
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