Views: 0 Author: Site Editor Publish Time: 2025-08-11 Origin: Site
The mold must be made from high-quality steel with:
High hardness (HRC ≥50) – To withstand long-term wear.
Mirror polishing (Ra ≤0.01μm) – Ensures smooth lens surfaces.
Corrosion resistance – Prevents degradation from plastic additives.
Common Mold Steels:
| Material | Key Features | Applications |
|---|---|---|
| S136H / STAVAX ESR | Excellent polishability, corrosion-resistant | High-end optical lenses |
| NAK80 | Pre-hardened, easy machining | Medium-volume production |
| H13 (Chrome-plated) | High wear resistance | Glass-filled plastics |
Minimize parting lines to avoid optical distortion.
Gate types:
Hot runner (preferred) – Reduces material waste.
Valve gate – Prevents weld lines.
Fan gate – Ensures uniform filling.
Conformal cooling channels (3D-printed molds) – Improve cooling uniformity.
Temperature control (±1°C) – Prevents warpage.
Micro vents (0.01–0.02mm deep) to avoid gas traps.
| Material | Light Transmittance | Characteristics | Applications |
|---|---|---|---|
| PMMA | 92% | High hardness, UV-resistant | Camera lenses, light guides |
| PC | 88% | Impact-resistant, prone to yellowing | Protective covers |
| COP/COC | 92% | Low birefringence, heat-resistant | Precision optics |
PMMA: 80°C for 4–6 hours (humidity <0.02%).
PC: 120°C for 4 hours (highly hygroscopic).
Melt filtration (5μm filter) – Removes impurities.
| Parameter | Control Guidelines |
|---|---|
| Melt Temperature | PMMA: 200–240°C / PC: 280–320°C |
| Mold Temperature | 60–100°C (±1°C) |
| Injection Speed | Fast filling (prevents weld lines) |
| Injection Pressure | High (100–150MPa) + gradual pressure drop |
| Back Pressure | 5–15MPa (improves melt uniformity) |
| Defect | Cause | Solution |
|---|---|---|
| Bubbles | Moisture / Poor venting | Improve drying / Optimize vents |
| Flow Marks | Uneven cooling / Wrong gate design | Increase mold temp / Use fan gate |
| Silver Streaks | Material degradation | Lower screw speed / Adjust temp |
| Birefringence | Internal stress | Optimize packing pressure / Annealing |
PMMA: 70–80°C for 2–4 hours.
PC: 110–120°C for 2–3 hours.
Anti-Reflective (AR) coating → Boosts light transmission (>98%).
Hard Coating (HC) → Improves scratch resistance.
| Test | Equipment | Requirement |
|---|---|---|
| Light Transmittance | Spectrophotometer | ≥90% (PMMA/COP) |
| Surface Defects | AOI (Automated Optical Inspection) | No scratches/bubbles |
| Surface Flatness | Interferometer | PV <0.1μm |
| Birefringence | Polariscope | Stress level ≤2 |
In-Mold Assembly (IMA) – Multi-component molding reduces alignment errors.
Glass Replacement – COP/COC offers glass-like clarity with lighter weight.
Smart Molding – AI-driven process optimization + real-time defect detection.
Producing high-transparency lenses requires:
Ultra-precise molds (mirror finish + conformal cooling).
High-purity materials (strict drying + filtration).
Precision process control (temp/pressure/speed optimization).
Post-treatment (annealing + coating + 100% inspection).
