Injection point
When molding LSR, a cold runner system is used. It can maximize the advantages of this adhesive material and improve production efficiency to the maximum extent. By processing the product in this way, there is no need to remove the glue injection channel, which avoids increasing the labor intensity of the operation and sometimes also avoids a large amount of material waste. In many cases, the structure without injection channels can also shorten the operation time.

The rubber injection nozzle is controlled by a needle valve for forward flow. Currently, many manufacturers can provide injection nozzles with pneumatic switches as standard equipment and can set them in various parts of the mold. Some mold manufacturers have specifically developed an open cold runner system, which has a very small volume, requiring multiple injection points to be set up within an extremely limited mold space (thereby filling the entire mold cavity). This technology makes it possible to produce high-quality silicone rubber products in large quantities without the need to separate the injection port.

If a cold runner system is used, it is important to establish an effective temperature gap between the hot mold cavity and the cold runner. If the runner is too hot, the rubber material may start vulcanizing before injection. But if it cools too quickly, it will absorb too much heat from the gate area of the mold, resulting in incomplete vulcanization.

For products injected using conventional sprues (such as submerged sprues and conical sprues), it is suitable to use small diameter injection ports for pouring (the diameter of the injection port is usually 0.2mm-0.5mm). Low viscosity LSR rubber, like thermoplastic rubber, requires a balanced flow channel system to ensure that all mold cavities are evenly filled with the rubber. By using simulation software for designing flow channel systems, the development process of molds can be greatly simplified, and its effectiveness can be proven through mold filling experiments.