PA66 — Polyamide 66 (Nylon 66)
Polyamide 66 (Nylon 66)
PA66 (polyamide 66) is a semi-crystalline thermoplastic that is stiffer and more heat-resistant than PA6, with fast crystallization. It is preferred for thermally loaded structural parts (connectors, engine components, demanding technical articles).
- Mold temperature: 60-90°C
- Melt temperature: 270-300°C
- Shrinkage: 1.0-2.0%
- Density: 1.13-1.15
- Manufacturer grades: Ultramid A3W (BASF), Zytel 101L (DuPont), Stabamid 27AE1 (Domo)
Processing
PA66 is hygroscopic: dry for about 4 h at 80 °C before molding to avoid silver streaks and hydrolysis. Its fast crystallization calls for a hot manifold and dynamic filling; process the melt between 280 and 295 °C and regulate the mold between 60 and 90 °C. Avoid over-drying and long residence times, which embrittle the material through degradation.
Advantages
- Higher stiffness and mechanical strength than PA6
- Better heat resistance (higher melting point)
- Fast crystallization: short cycles are achievable
- Good resistance to hydrocarbons and wear
Limitations
- Hygroscopic: drying mandatory and dimensional change with moisture
- Narrow processing window (fast crystallization, premature freeze-off)
- High shrinkage prone to warpage on flat parts
- Sensitive to over-drying and thermal degradation (embrittlement)
Common injection molding defects
- Warpage — Differential shrinkage and fast crystallization: balance mold cooling
- Weld lines — Fast freeze-off: raise melt temperature, speed and mold temperature
- Brittleness — Over-drying or thermal degradation: limit residence time and drying
Typical applications
Under-hood automotive parts, electrical connectors, structural parts