The hot runner system of two-color liquid silicone mold plays a decisive role in the precise distribution of the rubber material, which directly affects the quality and production efficiency of the final product.
First, the runner design of the hot runner is a key factor. The diameter, shape and length of the runner need to be carefully designed according to the characteristics of the silicone material and the size and shape of the product.
For example, for high-viscosity silicone, the runner diameter should be appropriately increased to reduce the flow resistance; while for products with complex shapes, a gradual runner design can be adopted so that the rubber can be evenly distributed to each cavity during the flow process. At the same time, the inner wall roughness of the runner should be as low as possible. Through precision machining and polishing processes, the retention and friction of the rubber in the runner can be reduced to ensure that the rubber can flow smoothly and stably, thereby achieving precise distribution.
Secondly, the optimization of the temperature control system of the hot runner is crucial. Silicones of different colors and types have different fluidity and reaction characteristics at different temperatures. Therefore, it is necessary to set high-precision temperature sensors at various key parts of the hot runner to monitor temperature changes in real time. The use of advanced temperature control modules can accurately adjust the temperature of each area and control temperature fluctuations within a very small range.
For example, when injecting the first color of silicone, set the temperature of the corresponding hot runner area to the optimal molding temperature. When switching to the second color of silicone, quickly adjust the temperature of the other hot runner area to ensure that the two rubbers enter the cavity at their respective appropriate temperature conditions to achieve accurate rubber distribution and good molding effects.
Furthermore, the design and layout of the hot runner manifold needs to be considered in depth. The manifold should have good thermal balance performance to avoid uneven flow of rubber due to local overheating or overcooling. A reasonable layout of heating elements and insulation structure are set inside the manifold to enable the rubber to maintain a stable temperature and pressure during the diversion process. At the same time, the connection between the manifold and each runner should be well sealed to prevent rubber leakage or pressure loss.
For example, special sealing materials and connection processes are used to ensure that during high-pressure injection, the rubber can only flow along the designed diversion path, thereby improving the accuracy of rubber distribution.
Finally, the collaborative design of the hot runner system and the mold as a whole cannot be ignored. The installation position of the hot runner, the distance from the cavity, and the opening and closing mechanism of the mold must be adapted to each other.
For example, the distance between the hot runner outlet and the cavity inlet should be as short as possible and the transition should be smooth to reduce the pressure loss and temperature change of the rubber during the transfer process. Through computer-aided design (CAD) and simulation analysis software, the hot runner system and the overall structure of the mold are virtually modeled and simulated, and the possible uneven distribution of rubber is predicted in advance, and optimized and adjusted to ensure that the hot runner system of the two-color liquid silicone mold can accurately distribute the rubber in actual production.
