Liquid silicone rubber injection molding is a thermoset process that cools the material delivery system, while heating the mold tool to cure silicone material into parts. The liquid injection molding process is highly automated with short cycle times to reduce the silicone part price.
Silicone rubber injection machine parts are elastic with a high degree of chemical, electrical and thermal resistance. In addition, the parts are biocompatible and can be subjected to sterilization without issue.
Silicone Rubber Injection Machine 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:
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.
Regardless of the industry, the liquid injection molding process allows for the fabrication of rubber parts or components that must withstand extreme conditions and make your products more effective. Industries and applications include:
Medical /Healthcare — Liquid silicone molding has made tremendous inroads into the medical industry because of its excellent physical properties and superior chemical and heat resistance. In addition, LSR offers numerous advantages, such as biocompatibility, easy sterilization and transparency.
The material feels soft on the skin, which makes it an obvious choice for devices that contact the body. The product also meets strict FDA standards. SIMTEC produces numerous products for the medical industry, including produced flow control valves, syringe stoppers and other components.
Automotive — LSR has durability, tensile strength, high thermal stability, fatigue and tear-resistance and other properties, which make it an excellent choice for components used under the hood of vehicles. Many OEMs and 1st and 2nd tier automotive suppliers prefer injection molding liquid silicone rubber to create a wide variety of standalone parts, including O-rings, buttons, components, gaskets and wiring harness components. LSR can also be molded directly onto plastic or metal parts.
Consumer products — The numerous properties found in liquid silicone rubber provide the raw material diversification required to manufacture a broad array of consumer products. These products range from kitchen bake ware and plastic showerheads to electronic gadgets and bottle dispensers.
Silicone Rubber Injection Machine Specialty applications — The numerous types and grades of liquid silicone rubber makes the material suitable for a wide range of other uses, including:
Valves and gauges
Membranes and seal rings
Irrigation and filtration parts
Pressure exit, check and one-way valves
Lighted panel buttons