Liquid silicone rubber (LSR) is a versatile material that can be molded into pliable, durable parts for a range of different industries and applications. Injection molding of LSR is a relatively simple process that allows manufacturers to produce high-quality parts with fast cycle times and low cost. However, there are a few key things that manufacturing engineers need to know about this type of liquid elastomer to get the most out of it.
LSR is a shear-thinning fluid, which means it has the ability to decrease in viscosity as force is applied to it. This is what makes it easy to flow into a mold when it is being injection molded. This property also helps LSR to conform to the shape of a part as it is being injected into a mold, which makes for very smooth surfaces in molded products.
The primary ingredients in an LSR compound are a base silicone oil and a platinum catalyst, which must be mixed together and pumped into an injection machine’s metering pumps. These pumps then deliver the two components of an LSR formulation into a hot injection mold to be cured. The resulting molded product will have superior physical properties, including resistance to water, oils and other chemicals, good electrical insulation, and high flexibility and elasticity.
These unique material properties make LSR the ideal choice for a wide variety of industry and consumer product applications, including items for cooking, baking and food storage, medical devices like baby bottle nipples, and many more. Because of its chemical resistance, molded LSR can be sterilized via steam autoclaving, ethylene oxide, gamma radiation and e-beam techniques. This is important because it ensures the safety of the people who will use the molded product.
Another advantage of molded LSR is its extreme temperature endurance. Unlike thermoplastic rubbers, which can melt or lose their elasticity at high temperatures, molded LSR maintains its physical properties at a variety of low and high temperatures. This makes it a great candidate for gaskets and seals that will be used in automobiles, data acquisition instruments and other ruggedized electronic devices where the molded product may be exposed to harsh weather conditions.
The ability of molded silicone to withstand high temperatures is what also makes it a good choice for automotive application, particularly in areas close to the engine where other elastomers would melt or degrade. It is also fire retardant, which makes it an excellent choice for a range of automotive interior components. Liquid silicone rubber is also an excellent choice for a variety of outdoor applications, as it can resist UV and ozone degradation and is resistant to tearing and weather damage.
The performance characteristics of a molded silicone can be further enhanced by the addition of metal particles, which makes the resulting materials electrically conductive. The presence of these particles can also help to make the molded material abrasion resistant, which is helpful for mechanical and chemical protection in high-stress areas of a component.