How is Silicone Rubber molded?
The Silicone rubber is molded with Vulcanized and curred. A combination of heat and pressure applied to the liquid silicone rubber cures the material until it solidifies.
There are 3 forms of Silicone Rubber and then with the 5 types of silicone rubber molded:
- Solid Silicone rubber Compression molded
- Liquid Silicone Rubber Injection molded
- Transfer molding
- RTV molding
- Dripping injection dispensing （co-injection）molding
Solid Silicone Rubber or High-Temperature Vulcanized, HTV – Solid silicone rubber contains polymers with a high molecular weight and relatively long polymer chains. They are available in uncured form and required traditional silicone rubber compression molding processing techniques.
Liquid Silicone Rubber, LSR – Liquid silicone rubber contains polymers of lower molecular weight and hence shorter chains. It has better flow properties. It is processed on specially designed injection molding and extrusion equipment.
Room Temperature Vulcanized, RTV – RTV silicone rubber is a type of silicone rubber made from one-part (RTV-1) or two-component (RTV-2) systems where their hardness range of very soft to medium. They are available for potting, encapsulations, sealants, etc.
Transfer molding: Transfer molding is a manufacturing process in which casting material is forced into a mold. Transfer molding is different from compression molding in that the mold is enclosed rather than open to the fill plunger resulting in higher dimensional tolerances and less environmental impact.
Compared to injection molding, transfer molding uses higher pressures to uniformly fill the mold cavity. This allows thicker reinforcing fiber matrices to be more completely saturated by resin. Furthermore, unlike injection molding, the transfer mold casting material may start the process as a solid. This can reduce equipment costs and time dependency. The transfer process may have a slower fill rate than an equivalent injection molding process.
Dripping injection dispensing （co-injection）molding: Dripping injection dispensing )Co-injection molding allows two different silicone materials (solid silicone rubber and liquid silicone rubber) to be combined into a single products stream. Liquid silicone’s colors can be adjusted according to different customers, and the colors will do nothing to the qualities of rockery liquid silicone. When in use, we need to mix the two parts evenly according to a certain proportion first, and then carry on the vacuum processing. This specialized process can be used to enhance products color performance and reduce cost without any penalty to cycle time or production volume. It is the perfect customize solution for difficult complex multicolored silicone products.
In Z.S.R Group, we can support you for the silicone rubber compression molded silicone products, custom LSR molded silicone products and custom molded multi-color products. Get in touch to learn more and order your custom-molded silicone rubber products.