The formation of silicone products depends on various factors. Silicone products are widely used in industries such as medical, food, electronics, and automotive due to their excellent high temperature resistance, corrosion resistance, flexibility, and environmental protection characteristics. However, the molding process of silicone products is complex, and their quality is affected by multiple factors. So, what factors determine the formation of silicone products? How to optimize the molding process to improve product quality?
1. Material formula
Basic polymer: The type of silicone rubber (such as high-temperature vulcanized silicone rubber HTV, liquid silicone rubber LSR, etc.) determines the choice of molding process.
Fillers and additives: Fillers such as white carbon black and calcium carbonate can enhance mechanical properties; Crosslinking agents (such as peroxides), vulcanization accelerators, inhibitors, etc. affect the vulcanization rate and product performance.
Liquidity: The viscosity and fluidity of the material directly affect the ability to fill the mold, and need to be adjusted according to the molding process (such as injection, extrusion).
2. Molding process
Compression molding: suitable for complex shapes, requiring control of pressure and temperature.
Injection molding: suitable for large-scale production, requiring high material fluidity and precise mold design.
Extrusion molding: used for continuous profiles such as pipes and sealing strips, requiring stable material extrusion and cooling control.
Liquid silicone rubber (LSR) molding: requires high temperature rapid vulcanization, relying on precise molds and temperature control systems.
3. Temperature control
Sulfurization temperature: Different vulcanization systems (such as platinum catalysis and peroxides) require specific temperature ranges. Insufficient temperature leads to incomplete vulcanization, while excessive temperature may decompose the material.
Mold temperature: Uniform mold temperature distribution ensures consistent product curing and avoids warping or defects.
4. Pressure and holding pressure
Filling pressure: sufficient pressure to fill the mold cavity with material, reducing bubbles and material shortage.
Pressure holding time: Maintain pressure until vulcanization is complete to prevent product shrinkage and deformation.
5. Mold design
Structural rationality: The parting surface, gate position, and exhaust hole design affect material flow and molding quality.
Surface treatment: Coating or polishing treatment can reduce silicone adhesion and facilitate demolding.
Dimensional accuracy: Mold wear or tolerances can directly affect product dimensional stability.
6. Sulfurization time
Positive sulfurization time: It is necessary to balance the degree of sulfurization and production efficiency, and avoid under sulfurization (low strength) or over sulfurization (high brittleness).
7. Environmental factors
Humidity and impurities: Condensed silicone requires moisture curing, while additive molding requires a dry environment; Dust or oil stains may cause surface defects.
Production environment temperature: affects material flowability and vulcanization rate.
8. Post processing
Edge trimming and cleaning: Remove burrs and residual release agents to enhance the appearance.
Secondary vulcanization: further removing low molecular weight substances, improving high temperature resistance and stability.
