Materials are Used to Make Silicone Vacuum Casting by Binashree

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Materials are Used to Make Silicone Vacuum
Casting by Binashree
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The process of silicone vacuum casting starts
with preparation of a model based on a drawing
with the use of stereolithography or CNC
machining. Once this model is ready then several
coats of silicone RTV resin of the right grade
are applied to create the mould. It is then cut
into two, the model extracted and the silicone
shell used for silicone vacuum casting processes.
Vacuum casting ensures that there are no air
bubbles that can show up as pinholes and defects.
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Polyurethane is one of the best choices for
engineering grade components that can be made
with silicone vacuum process. Polyurethane is
available in various grades and types with
specific properties. Most polyurethanes are cured
at high temperature. Then there are variants of
polyurethane. Polyurethane resin mixes used in
this process commonly have properties similar to
ABS. These have various properties such as
exceptional mechanical strength, heat deflection
and flexural resistance as well as impact
resistance.
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Rubber elastomers can also be used with silicone
moulds in the vacuum casting process. Most such
compounds include silicone itself with various
properties, urethane rubber and other elastomers
to create seals and gaskets at a low
cost. Polycarbonates may also be used with
silicone moulds for vacuum casting where high
shock resistance and strength are desirable or
where high transparency is required.
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There are dozens of PU modified ABS/PC/PP/PMMA
resins available to suit various parameters of
the finished components as well as cost.
Binashree technical experts are quite familiar
with these resins. Choice of resin from which
part is going to be moulded plays a role in
influencing mould design and choice of the
silicone compound from which the mould is to be
made as regards hardness, flexibility and
durability. All these factors are taken into
consideration when a client expresses a desire to
get a part developed through vacuum casting.
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