Injection molding of liquid silicone
rubber (LSR) is a process to produce
pliable, durable parts in high volume.
Liquid silicone rubber is a high purity
platinum cured silicone with low compression
set, great stability and ability to resist
extreme temperatures of heat and cold
ideally suitable for production of parts,
where high quality is a must. Due to the
thermosetting nature of the material, liquid
silicone injection molding requires special
treatment, such as intensive distributive
mixing, while maintaining the material at a
low temperature before it is pushed into the
heated cavity and vulcanized.
Chemically, silicone rubber is a family
of thermoset elastomers that have a backbone
of alternating silicone and oxygen atoms and
methyl or vinyl side groups. Silicone
rubbers constitute about 30% of the silicone
family, making them the largest group of
that family. Silicone rubbers maintain their
mechanical properties over a wide range of
temperatures and the presence of
methyl-groups in silicone rubbers makes
these materials extremely hydrophobic.
Typical applications for liquid silicone
rubber are products that require high
precision such as seals, sealing membranes,
electric connectors, multi-pin connectors,
infant products where smooth surfaces are
desired, such as bottle nipples, medical
applications as well kitchen goods such as
baking pans, spatulas, etc. Often, silicone
rubber is overmolded onto other parts made
of different plastics. For example, a
silicone button face might be overmolded
onto an ABS housing.