Silicone molding technology is a manufacturing process that transforms liquid silicone rubber (LSR) or solid silicone compounds into precision-shaped products via controlled curing. It leverages silicone’s unique elasticity, heat resistance, and biocompatibility to serve industries from cultural relic protection to medical devices. But what makes this technology versatile, how do you select the right methods for specific needs, and how to avoid common production pitfalls?
1. Core Types of Silicone Molding Technology: A Comparative Analysis
Silicone molding technology varies by material state and curing mechanism. The table below breaks down key types, their strengths, and ideal uses:
| Technology Type | Key Characteristics | Advantages | Limitations | Ideal Application Scenarios |
| Liquid Silicone Rubber (LSR) Molding | Uses two-component LSR (mixed 1:1 or 10:1); cures at 120–180°C | High precision (±0.01mm); no by-products; fast cycle time (30–60s/part) | High equipment cost; requires specialized injection machines | Medical devices (e.g., prosthetic components), baby products (e.g., pacifier nipples) |
| Solid Silicone Compression Molding | Uses pre-cut solid silicone sheets; pressed in molds (160–200°C, 10–20MPa) | Low equipment investment; suitable for large parts; easy to scale | Longer curing time (5–10min/part); lower detail resolution | Industrial seals, automotive gaskets, large craft molds |
| Silicone Coating & Dipping | Applies thin silicone layers via brushing/dipping; cures at room temp or low heat | Uniform thickness (5–500μm); adheres to diverse substrates (metal, fabric) | Limited to thin-walled products; slow for thick layers | Electronic component waterproofing, cultural relic protective coatings |
| Vacuum-Assisted Silicone Molding | Uses vacuum chambers to eliminate bubbles during pouring; for LSR or solid compounds | No bubble defects; high surface finish (Ra≤1.6μm) | Longer process time; requires vacuum equipment | Precision jewelry molds, optical components, cultural relic replication |
2. Material Selection for Silicone Molding: Match to Performance Needs
The success of silicone molding depends on choosing the right silicone type. Below is a guide to material categories and their key parameters:
A. Silicone Material Categories
| Material Category | Key Features | Compliance Standards | Typical Use Cases |
| Condensation-Cure Silicone | Releases ethanol during curing; low cost; easy to operate | Industrial-grade (no food/medical compliance) | Ordinary crafts, non-critical seals |
| Addition-Cure Silicone | No by-products; low shrinkage (<0.1%); high purity | FDA/ISO 10993 (medical); FDA 21 CFR (food) | Medical prosthetics, food-contact molds (e.g., chocolate molds) |
| Fluorosilicone | Heat resistance up to 300°C; chemical resistance (acids, oils) | MIL-STD-883 (aerospace); ASTM D2000 (automotive) | Aerospace seals, high-temperature industrial gaskets |
B. Critical Material Parameters to Consider
- Hardness (Shore A):
- 5–10°: Ultra-soft (cultural relic cushions, medical skin contact parts)
- 20–30°: Medium-soft (resin craft molds, baby product components)
- 40–60°: Hard (industrial seals, automotive gaskets)
- Viscosity:
- Low (<5,000 cP): Flows into micro-details (jewelry molds, electronic component coatings)
- High (>10,000 cP): Ideal for brushing/dipping (thick protective layers for cultural relics)
- Tear Strength:
4kN/m: High-durability needs (reusable molds, frequent-use seals)
- 2–3kN/m: Budget-friendly, low-cycle products (disposable craft molds)
3. Standardized Workflow of Silicone Molding Technology
A typical silicone molding process follows 5 key stages, with strict controls at each step to ensure quality:
Stage 1: Pre-Production Preparation
- Prototype & Mold Design:
- For uneven substrates (wood, stone), spray PVA water-soluble release agent to prevent silicone adhesion.
- Add chamfers (0.5–1mm) to mold edges to avoid stress concentration and tearing.
- For deep-hole structures, embed magnetic nuts for post-molding positioning.
- Tooling Setup:
- Build a containment frame (glass/acrylic) 10cm taller than the prototype’s highest point to prevent overflow.
- Reserve a glue injection port (diameter ≥1cm) and serpentine exhaust grooves to release air.
Stage 2: Material Preparation & Mixing
- Component Mixing:
- For LSR: Use an electronic scale to weigh AB components (e.g., 1:1 ratio) with ±0.1g accuracy.
- For solid silicone: Cut compounds into blanks matching the mold’s cavity volume (add 5–10% for compression shrinkage).
- Defoaming:
- Place mixed LSR in a vacuum chamber (-0.1MPa) for 15–20 minutes; repeat 2–3 times at 5-minute intervals for bubble-free results.
Stage 3: Molding & Curing
| Technology Type | Molding Process | Curing Parameters |
| LSR Molding | Inject mixed LSR into heated molds (120–150°C) via specialized injection machines | Cure time: 30–60s; pressure: 5–10MPa |
| Compression Molding | Place solid silicone blanks in molds; apply pressure (10–20MPa) and heat (160–180°C) | Cure time: 5–10min; post-cure at 200°C for 2h to eliminate stress |
| Coating/Dipping | Brush/dip substrate in silicone; let stand for 10–15min to level | Room-temperature cure: 24h; low-heat cure: 60°C for 2h |
Stage 4: Demolding & Post-Processing
- Demolding:
- Use thin plastic sheets to separate silicone from molds; tap the back gently to vibrate stuck parts.
- For complex molds, pre-cut guide grooves (depth ≤1/3 of mold thickness) to ease peeling.
- Trimming & Finishing:
- Cut excess flash with sharp scissors; sand inner surfaces with 400–600 grit sandpaper for Ra≤1.6μm smoothness.
Stage 5: Quality Inspection
- Dimensional Stability: Measure key dimensions 3 times with a caliper; ensure tolerance within ±0.5%.
- Surface Quality: Use a roughness meter to verify Ra≤1.6μm; check for pockmarks or bubbles.
- Performance Testing: For high-cycle products, run dynamic fatigue tests (≥100,000 folds without tearing).
4. Troubleshooting Common Issues in Silicone Molding
Even with precise controls, issues may arise. Below is a cause-and-solution guide for frequent problems:
| Problem Phenomenon | Root Cause | Practical Solution |
| Surface Pockmarks/Imperfections | Substrate contamination (oil/dust); environmental dust adhesion | – Clean prototypes with alcohol; operate in a dust-free workshop.- Apply a thin release agent layer to smooth uneven surfaces. |
| Uneven Thickness | Turbulence from fast pouring; mold cavity design flaws | – Use a funnel for slow, layered pouring (1–2cm/min).- Optimize mold vents to balance pressure distribution. |
| Bubble Trapping | Inadequate vacuum defoaming; mixing too vigorously | – Extend vacuum time to 20–25min; add a second defoaming cycle.- Stir silicone at 30–50 RPM (avoids air entrapment). |
| Edge Curl | Uneven curing shrinkage; high exotherm during molding | – Switch to low-temperature curing (reduce by 10–15°C).- Add a 2-hour post-cure at 60°C to relieve internal stress. |
| Short Service Life | Resin/chemical residue corrosion; UV aging | – Clean molds with steam + neutral detergent after each use.- Store molds in opaque containers (avoids UV exposure); apply talcum powder for long-term storage. |
5. Industry-Specific Applications of Silicone Molding Technology
Silicone molding technology solves unique challenges across sectors. Here are key use cases with implementation details:
| Industry | Application Case | Molding Technology Used | Key Innovations |
| Cultural Relic Protection | Fragile relic support & shape replication | Vacuum-assisted LSR molding (5° Shore A ultra-soft silicone) | Embedded optical fiber sensors to monitor relic stress in real time; glass fiber reinforced layer for durability |
| Medical Devices | Custom orthotic insoles | Addition-cure LSR molding (biocompatible grade) | 3D-scanned prototypes for personalized fit; post-cure at 120°C to meet ISO 10993 biocompatibility standards |
| Toy Manufacturing | Limited-edition doll molds (multi-color parts) | Modular compression molding (colored silicone) | Separate head/body molds with magnetic positioning; colored silicone for easy part identification |
| Electronics | Circuit board waterproofing | Silicone coating (low-viscosity LSR) | Uniform 20μm coating; cures at 80°C to avoid damaging electronic components |
6. Yigu Technology’s Perspective on Silicone Molding Technology
At Yigu Technology, we see silicone molding technology as a bridge between precision engineering and creative needs. For cultural relic protection projects, our vacuum-assisted LSR molding (5° Shore A silicone) has successfully replicated 200+ fragile artifacts, with 0.1mm detail accuracy and real-time stress monitoring. For medical clients, our addition-cure LSR molding process meets FDA 21 CFR standards, delivering custom prosthetic components with <0.01mm dimensional tolerance.
We’re advancing two key innovations: 1) Developing eco-friendly LSR (reducing VOCs by 35%) for sustainable manufacturing; 2) Integrating AI into mold temperature control (optimizing curing time by 20% while maintaining quality). Our goal is to make silicone molding technology more accessible, efficient, and tailored to industry-specific challenges.
FAQ
- What’s the difference between LSR molding and solid silicone compression molding for medical products?
LSR molding is ideal for high-precision, small medical parts (e.g., catheter tips) due to its ±0.01mm tolerance and biocompatibility (no by-products). Solid silicone compression molding works for larger parts (e.g., orthotic braces) and has lower equipment costs but longer cycle times. Always choose addition-cure LSR for implantable/skin-contact medical products.
- How to extend the service life of silicone molds made via this technology?
Clean molds with steam + neutral detergent (avoid sharp tools) after each use; store in opaque, dry containers (prevents UV aging); apply a thin talcum powder layer for storage over 1 month. For high-frequency use, add a 2-hour post-cure at 60°C every 50 cycles to refresh elasticity.
- Can silicone molding technology be used for high-temperature industrial parts (e.g., 250°C+)?
Yes—use fluorosilicone material (heat resistance up to 300°C) with compression molding (180–200°C cure). Ensure a 4-hour post-cure at 220°C to enhance heat resistance. This setup is suitable for aerospace seals and high-temperature industrial gaskets, meeting MIL-STD-883 standards.