PA6 — Polyamide 6 (Nylon 6)
Polyamide 6 (Nylon 6)
PA6 (polyamide 6) is a tough semi-crystalline thermoplastic valued for its abrasion and fatigue resistance. Widely used for technical injection molded parts (gears, bearings, under-hood components), it offers a solid mechanical balance but remains highly hygroscopic.
- Mold temperature: 60-90°C
- Melt temperature: 240-280°C
- Shrinkage: 0.8-1.5%
- Density: 1.13-1.15
- Manufacturer grades: Ultramid B3S (BASF), Akulon F223-D (DSM), Durethan B30S (Lanxess)
Processing
PA6 is highly hygroscopic: drying for about 4 h at 80 °C is mandatory before molding, otherwise residual moisture causes silver streaks and hydrolysis that degrades the chains and collapses mechanical properties. Process the melt between 250 and 270 °C, regulate the mold between 60 and 90 °C to control crystallinity, and limit barrel residence time to avoid thermal degradation.
Advantages
- Excellent abrasion and fatigue resistance
- Good toughness and impact strength (even at low temperature)
- Good resistance to hydrocarbons, oils and greases
- Very well suited to glass-fiber reinforcement
Limitations
- Highly hygroscopic: absorbs moisture, dimensional change after molding
- Strict drying mandatory before every molding run
- Significant, anisotropic shrinkage prone to warpage
- Mechanical properties depend on moisture content (conditioning)
Common injection molding defects
- Silver streaks — Residual moisture: dry PA6 for 4 h at 80 °C before molding
- Warpage — Differential shrinkage: homogenize mold cooling and the holding profile
- Sink marks — On thick sections: increase holding pressure and time
Typical applications
Gears, clips, connectors, mechanical parts