Injection molding of liquid silicone rubber

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, good stability and ability to resist extreme temperatures of heat and cold ideally suitable for production of parts, where high quality is required. 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 silicon 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, making them suitable for electrical surface insulations.

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 as 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 a Nylon 6,6 housing.