1. Silicone Material Characteristics

• Types: Mainly divided into Liquid Silicone Rubber (LSR) and High-Temperature Vulcanization Silicone Rubber (HCR).

  • LSR: Low viscosity, ideal for intricate structures, rapidly cures under heat (typically 120–200°C).

  • HCR: High-viscosity solid rubber requiring higher temperature and pressure, often used for large or high-hardness products.

• Advantages: High temperature resistance (-50°C to 250°C), flexibility, biocompatibility, and chemical stability.

2. Process Workflow

1. Material Preparation:

   • LSR requires precise mixing of A/B components (typically 1:1 ratio) to avoid air bubbles; HCR needs preheating for softening.

2. Mold Design:

   • Runner and Venting: Wide runners reduce flow resistance; multiple vent slots prevent trapped air.

   • Temperature Control: LSR molds require heating (electric or oil systems); HCR molds demand higher temperatures.

   • Surface Treatment: Polishing or coatings (e.g., Teflon) to aid demolding.

3. Injection Molding:

   • Equipment: Dedicated silicone injection machines with cooled screws to prevent premature curing.

   • Parameters: Low injection pressure (LSR: ~10–30 MPa), precise temperature, and injection speed control.

4. Curing and Demolding:

   • LSR cures in 1–5 minutes in-mold; HCR requires longer curing times.

   • Post-curing (e.g., 200°C/4 hours) may enhance performance.

5. Post-Processing: Trimming, cleaning, and quality checks (dimensions, hardness, tear resistance).

3. Key Challenges & Solutions

• Air Bubbles: Use vacuum injection machines or optimize venting in mold design.

• Shrinkage: LSR shrinkage (~0.1–0.3%) requires mold compensation.

• Mixing Uniformity: Static mixers ensure thorough blending of A/B components to avoid partial curing defects.

4. Applications

• Medical: Catheters, prosthetics, respiratory masks (biocompatibility certifications like ISO 10993).

• Automotive: Seals, cable sheaths (oil/aging resistance).

• Consumer Electronics: Waterproof gaskets, buttons (wear resistance, insulation).

• Food-Grade: Baking molds, nipples (FDA compliance).

5. Equipment Selection

• Injection Machines: Horizontal machines with metering pumps and static mixers are recommended.

• Mold Materials: High-hardness, corrosion-resistant steels (e.g., S136 mirror steel).

6. Economic Considerations

• Mold Costs: High for complex molds, suitable for large-scale production (e.g., 10k+ units).

• Efficiency: LSR cycles are short (~1–3 minutes), ideal for rapid mass production.

7. Innovation Trends

• Micro-Injection Molding: For micro medical devices (e.g., microfluidic chips).

• Automation Integration: Robotics and AI-based quality inspection to improve yield.