The system design of injection points is the core breakthrough point for improving the production efficiency of liquid silicone rubber. For the injection molding process of liquid silicone rubber, the cold runner system is a mature solution that is highly suitable. It can fully utilize the processing characteristics of this type of rubber material and improve production efficiency to a higher level. When using this structure to process products, there is no need for additional removal of runner aggregates, which not only avoids additional manual cleaning processes but also reduces unnecessary material waste. In most cases, it can effectively shorten the overall molding cycle.

The injection nozzle of the rubber material relies on a needle valve to achieve forward flow control. Currently, this type of injection nozzle with pneumatic switch has become a common configuration in the industry, which can be flexibly arranged at various suitable positions inside the mold. In some mold designs, an open cold runner system with a very compact volume will also be used. Even in molds with extremely limited space, multiple injection points can be arranged to evenly fill the entire mold cavity with rubber material. This technology enables the mass production of high-quality silicone rubber products without the need for additional post-processing steps such as gate separation.


In the design of a cold runner system, an effective temperature isolation zone must be established between the high-temperature mold cavity and the low-temperature runner. If the temperature of the runner is too high, the rubber material is likely to undergo vulcanization before the injection is completed; But if the runner is excessively cooled, it will absorb too much heat from the gate area of the mold, causing the rubber material near the gate to not be fully vulcanized. For products using conventional gating systems, such as submerged and tapered gating structures, it is suitable to use small-diameter sprues for feeding, with the diameter of the sprue typically controlled between 0.2mm and 0.5mm.

Similar to the processing logic of thermoplastic rubber, the low viscosity characteristics of liquid silicone rubber also require the flow channel system to maintain good flow balance, so as to ensure that all mold cavities can be uniformly filled with rubber. With the help of specialized channel system simulation software, the development process of molds can be greatly simplified, and the effectiveness of design schemes can be verified in advance through mold filling simulation.


The design of the demolding system directly affects the final integrity of the product. The liquid silicone rubber that has completed vulcanization is easily adhered to the metal surface, and coupled with the generally good flexibility of the product itself, it can easily hinder the demolding process. However, liquid silicone rubber has good tear strength in high temperature environments, which allows it to be smoothly removed from the mold cavity under conventional demolding conditions, and even larger products are not easily torn or damaged. The most commonly used demolding techniques in the industry currently include demoulding with demoulding templates, demoulding with demoulding pins, and pneumatic demoulding. In addition, roller scraping, export plate demoulding, and fully automatic demoulding are also common auxiliary demoulding methods.

When designing and processing demolding systems, it is necessary to ensure that the fitting accuracy of all components is maintained within a high standard range. If the gap between the top push pin and the guide pin sleeve is too large, or if the gap exceeds the standard after long-term wear of the components, it is easy to cause glue overflow problems. Inverted conical or mushroom shaped top sales can achieve better usage effects. This structure can withstand greater contact pressure, effectively improve the sealing performance of the mating position, and reduce the probability of glue overflow.