
Headlight interiors operate under harsh conditions, requiring materials to meet these demands:
High temperature resistance (lamp cavity temperatures up to 120–150℃ for LED/xenon lamps)
Dimensional stability (no warping, air leakage or water leakage)
Thermal shock resistance (no cracking under thermal cycles from -40℃ to 150℃)
High strength, good toughness and vibration resistance
Good injection moldability and cost efficiency
PC/ABS has insufficient heat resistance, while PBT offers mediocre toughness. Glass fiber reinforced nylon provides the best overall performance.
2. Most Common Modified Nylon Systems
2.1 Glass Fiber Reinforced PA6 (Cost-effective Standard Grade)
Typical: PA6+GF20 / GF30
Advantages: Good flowability, easy molding, low cost
Application: Rear covers of standard headlights, peripheral housings, non-high-temperature brackets
Long-term heat resistance: approx. 110–120℃
2.2 Glass Fiber Reinforced PA66 (High-strength Heat-resistant Grade)
Typical: PA66+GF25 / GF30
Advantages: Significantly better rigidity, heat resistance and creep resistance than PA6
Application: Main headlight housings, rear covers, adjusting mechanism bases
Long-term heat resistance: approx. 125–130℃
Industry standard material
2.3 PA66/PA6 + Glass Fiber + Mineral Filler (Low-warpage Special Grade)
Typical: approx. GF15+Mineral20
Advantages: Minimal warpage, smooth surface, ideal for large rear covers
Application: Large-size lamp housings, rear covers, exterior covers
2.4 High-temperature Nylon (PPA / PA6T / PA9T) for High-end LED Headlights
Advantages: Ultra-high heat resistance, low moisture absorption, excellent dimensional stability
Application: Module bases and reflector brackets near LED light sources (highest temperature zones)
Long-term heat resistance: above 150℃
2.5 Toughened Cold-resistant Nylon (Essential for Frigid Regions)
Modified with grafted POE / EPDM
Ensures no brittle fracture at -30℃ to -40℃
2.6 UV-stabilized Weather-resistant Nylon (For Exposed Parts)
Added UV stabilizers and antioxidants
Prevents yellowing and embrittlement from long-term sun exposure.

Heat Deflection Temperature (HDT): ≥220℃ (1.82MPa)
Long-term heat aging: No cracking or deformation after 1000h at 130℃
Low-temperature toughness: No brittle fracture under impact at -30℃
Dimensional stability: Low moisture-induced deformation, leak-proof assembly
Thermal shock resistance: No cracking after 200 cycles between -40℃ and 120℃
Environmental compliance: Meets ELV, halogen-free and low-VOC requirements.
4. Material Selection by Component
| Component | Recommended Material | Reasons |
|---|---|---|
| Headlight rear cover | PA66+GF30 / PA6+GF30 | Good heat resistance, sufficient strength, moderate cost |
| Main headlight housing | Low-warpage PA66+GF30 | Minimizes deformation for large surfaces |
| Base near light source | PPA/PA6T+GF30 | High heat resistance and dimensional stability |
| Adjusting bracket / clip | Toughened PA66+GF25 | High toughness and vibration resistance |
| Exposed decorative cover | UV-stabilized PA66+GF | Prevents aging from sunlight |


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