The molding production of dual-color conductive silicone rubber accessories is a traditional yet highly reliable molding process, especially suitable for manufacturing precision components with complex structures, strict requirements for conductivity, and requiring large-area encapsulation or embedded structures (such as plug seals, multi-function instrument buttons, etc.).
The following is a detailed explanation of its molding production process and its role:
一. Molding production process
The core of dual-color conductive silicone rubber molding lies in the molecular-level combination of two types of silicone rubber with different characteristics within the mold, achieved through two feeding processes and thermal vulcanization.
1. Raw material preparation and preforming
According to the product performance requirements, two types of rubber compounds are prepared: one is conductive silicone rubber filled with conductive fillers (such as silver-plated nickel powder, conductive carbon black, and silver-plated glass microspheres); the other is insulating silicone rubber without conductive fillers. The two rubber compounds are separately mixed through an open mill and cut into rubber blanks of specific weight and shape for placement into the mold cavity.
2. First feeding and molding
Place the conductive silicone rubber blank into the lower mold cavity or specific conductive area. After mold closing, conduct the first vulcanization under high temperature (usually 160°C-180°C) and high pressure. This stage usually adopts a semi-vulcanization process, which allows the conductive silicone rubber to be initially set but retains chemical activity on the surface, preparing for subsequent bonding.
3. Secondary feeding and molding
Open the mold, fill the semi-finished conductive silicone rubber matrix with insulating silicone rubber paste. Re-close the mold for the second high-temperature and high-pressure vulcanization. Under pressure, the insulating silicone rubber flows and fills the remaining cavity, while undergoing co-vulcanization reaction with the conductive silicone rubber at the interface, forming a solid integrated structure.
4. Secondary vulcanization and finishing
The molded product undergoes secondary vulcanization (baking) to eliminate internal stress and stabilize its elasticity and electrical conductivity. Finally, burrs are removed through manual or frozen trimming, and quality inspection is completed.
二. Core role
1. Realize the composite function of conductivity and insulation
The molding process enables control over the distribution of conductive silicone rubber. For instance, in the sealing ring of a connector, the internal closed circuit utilizes conductive silicone rubber to ensure grounding conductivity between the body and the panel, while the external contact part employs insulating silicone rubber to prevent accidental electrical contact. This composite structure cannot be achieved with a single material.
2. Provide excellent pressure resistance and sealing performance
The high pressure during molding results in a dense molecular structure of silicone. The conductive part not only conducts electricity but also serves as an electromagnetic shield (EMC). The insulating part utilizes the high resilience of silicone to maintain stable waterproof and dustproof sealing under severe temperature changes or vibration environments.
3. Withstand harsh environments
Due to the conductive filler being completely encapsulated by the silicone rubber substrate, the molded product can maintain stable conductive performance and physical structure even under long-term outdoor exposure, ozone, or salt spray corrosion environments, without experiencing issues such as coating peeling or conductive particle migration leading to short circuits.
