Manufacturing and Molding
The production process of Liquid Silicone Rubber (LSR) involves several steps: material preparation, mixing, degassing, injection molding, curing, demolding, and quality inspection. Here is a detailed description of the process:
The first step in producing LSR is preparing the materials. LSR typically consists of two components: Part A and Part B. Part A mainly contains the silicone rubber base polymer and additives such as plasticizers, fillers, and pigments; Part B mainly contains the cross-linking agent (usually a platinum catalyst) and other additives. These two parts must be precisely weighed according to the formulation to ensure the final product's performance and quality.
Part A and Part B are mixed together in the specified ratio. Mixing can be done manually or using specialized mechanical equipment. Mechanical mixers often come with static or dynamic mixers to ensure uniform mixing of the two components. Care must be taken to avoid introducing air bubbles and contaminants during the mixing process.
The mixed LSR compound may contain air bubbles, which can affect the appearance and performance of the final product. Therefore, degassing is necessary. Degassing is usually performed under vacuum conditions. The mixture is placed in a vacuum chamber where the pressure is lowered to allow air bubbles to rise and escape until the mixture is bubble-free.
The degassed LSR compound is injected into a mold using an injection molding machine. The machine consists of a material reservoir, an injection unit, and a mold. The material reservoir heats the LSR compound to enhance its flowability; the injection unit injects the compound into the mold cavity under high pressure; the mold is designed according to the shape and dimensions of the final product.
The LSR injected into the mold needs to be cured at a certain temperature. The curing process is usually carried out under heated conditions, with temperature ranges typically between 120°C and 180°C, depending on the material formulation and product requirements. During curing, the silicone rubber molecules form a three-dimensional network structure through the cross-linking agent, giving the silicone rubber excellent mechanical properties and stability.
Once curing is complete, the mold is opened, and the molded silicone rubber product is carefully removed. Depending on the product, some post-processing steps may be required, such as trimming excess material, finishing, and surface treatment. For certain special applications, secondary curing may be needed to further enhance product performance.
The finished LSR products undergo rigorous quality inspection. Inspection items include visual inspection, dimensional measurement, physical performance tests (such as hardness, tensile strength, and elongation at break), and special performance tests (such as high and low-temperature resistance, chemical resistance, etc.). Only products that pass these inspections are allowed to be shipped and sold.
Summary
The production process of Liquid Silicone Rubber involves material preparation, mixing, degassing, injection molding, curing, demolding, and quality inspection. Each step requires strict control to ensure the high quality and stability of the final product. Proper implementation of these steps not only ensures the performance of LSR products but also meets the demands of various applications.
