Because Liquid Silicone Rubber(LSR) is a kind of non-toxic, heat-resistant, highly resilient transparent thermosetting organ material. Its sulfur change behavior is mainly included: low viscosity, rapid curing, shear thinning, and high thermal expansion coefficient. Two-component Liquid Silicone Rubber with high transparency, high strength, and tear resistance, is suitable for Silicone Injection Molding.

Liquid Silicone Injection Molding is a thermosetting molding process that injects mixed Component A containing a platinum catalyst and Component B containing methyl hydrogen siloxane into a mold cavity by the ratio of 1:1. Under the action of high temperature and high pressure rapid crosslinking reaction, the two-component liquid silicone rubber will be solidified into silicone component or product.

How does liquid silicone injection molding work? There are complete steps.

• The uncured liquid silicone rubber was in two separate containers, type A and type B, which are linked to a pumping system. Type A contains a platinum catalyst, while Type B contains methyl hydrogen siloxane. The metering system will automatically release the two types of components at the ratio of 1:1 and properly add any pigment.

• The molder can design and customize the injection molding machines to make sure of the precise shot size for the project. According to different requirements, the platens and pistons can be set at different temperatures, injection rates, and cycle periods.

• After the complete setup, the injection molding machine will heat the mold to a suitable temperature and actively adjust the clamping force. Then the mold is closed, cooperating with the pump, and the injector to inject the liquid silicone rubber into the mold cavity.

• Heating and stressing work should maintain during the course of injection molding until the material is solidified. The cycle can be repeated until finishing the bulk manufacturing.

• After removing the components from the mold, de-flashing, quality control, testing, and packaging are the post-molding services.

When using injection molding technology, any parts or products manufactured originate from the mold. The main manufacturing molding systems include cold runner injection molding and hot runner injection molding. The hot runner use screw nozzles that are fed through a barrel using a pump, while the cold runner is matched with a closed, thermosetting mold. The injection moldings are all designed to direct the material flowing from the sprue to the cavity mold. The system needs extra pressure to push the material through the runner. The frictional heat made in the runner by the material flow through the runner and heat the temperature to push the flowing of the material.

Cold Runner Injection Molding

Cold runner injection mold usually consists of a mold base within two or three separate panels. The thermoplastic silicone material is injected through the nozzle and the sprue and filling the entire port network to the mold cavity. This system has an unheated runner that can distribute the silicone into each molding cavity.

Double plate cold runner mold: in this type of cold runner mold runner and sprue are connected with the final product. The process uses the pop-up system to separate these parts and the final parts.

Three-board cold runner mold: a stripper template is used to contain the sprue to provide the required amount of molten thermoplastic material. In this system, the flow tract is separated from the mold when open.

Hot Runner Injection Molding

There are two plate molds of hot flow tract which can be used to receive the necessary heat from the manifold system. The way to keep consistency for the hot runner system is by putting the heating tube and liquid silicone at the same temperature.

The heat runner has a separate plate and shell which is fixed during the whole process. When the molding board is opened, the final product is without an additional runner.

Although there are many different types of systems that use hot runner mold, the two categories are internal and external heat. The former is the ideal choice of the polymer who is sensitive to temperature change, and the latter provides enhanced flow control.