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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 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. 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 an Nylon 6,6 housing. ==Equipment== In order for the liquid injection molding process to fully occur, several mechanical components must be in place. Typically, a molding machine requires a metered pumping device in conjunction with an injection unit—a dynamic or static mixer is attached. An integrated system can aid in precision and process efficiency. The critical components of a liquid injection molding machine include:〔(Liquid Injection Molding )〕 Injectors. An injecting device is responsible for pressurizing the liquid silicone to aid in the injection of the material into the pumping section of the machine. Pressure and injection rate can be adjusted at the operator’s discretion. Metering Units. Metering units pump the two primary liquid materials, the catalyst and the base forming silicone, ensuring that the two materials maintain a constant ratio while being simultaneously released. Supply Drums. Supply drums, also called plungers, serve as the primary containers for mixing materials. Both the supply drums and a container of pigment connect to the main pumping system. Mixers. A static or dynamic mixer combines materials after they exit the metering units. Once combined, pressure is used to drive the mixture into a designated mold. Nozzle. To facilitate the deposition of the mixture into the mold, a nozzle is used. Often, the nozzle features an automatic shut-off valve to help prevent leaking and overfilling the mold. Mold Clamp. A mold clamp secures the mold during the injection molding process, and opens the mold upon completion. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Injection molding of liquid silicone rubber」の詳細全文を読む スポンサード リンク
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