Chemical Structure Differences
The fundamental difference between PA6 (Nylon 6) and PA66 (Nylon 66) lies in their molecular structure:
- Nylon 6: Made from caprolactam, has 6 carbon atoms in each repeating unit. Less crystalline structure.
- Nylon 66: Made from hexamethylenediamine and adipic acid, has two 6-carbon chains. More crystalline structure.
Mechanical Properties Comparison
| Property | PA6 | PA66 |
|---|---|---|
| Tensile Strength | 70-85 MPa | 80-100 MPa |
| Flexural Modulus | 2.5-3.0 GPa | 2.8-3.5 GPa |
| Elongation at Break | 30-100% | 15-60% |
| Notched Izod Impact | 50-100 J/m | 40-80 J/m |
| Melting Point | 220°C | 260°C |
| HDT at 1.8 MPa | 70°C | 90°C |
Moisture Absorption
Moisture absorption is critical for nylon applications:
| Condition | PA6 | PA66 |
|---|---|---|
| At 50% RH | 2.5-3.0% | 2.0-2.5% |
| Saturation | 8-10% | 6-8% |
Processing Characteristics
Nylon 6 Processing
- Melting Point: 220°C
- Processing Range: 240-280°C
- Mold Temperature: 40-80°C
Nylon 66 Processing
- Melting Point: 260°C
- Processing Range: 280-320°C
- Mold Temperature: 60-90°C
Applications by Material
Nylon 6 Applications
- Gears and sprockets
- Industrial monofilament
- Film and packaging
- Consumer products
Nylon 66 Applications
- Automotive under-hood components
- Electrical connectors
- High-temperature bearings
- Precision mechanical components
Reinforced Grades
Both materials are commonly reinforced with glass fiber:
| Grade | PA6 + GF30 | PA66 + GF30 |
|---|---|---|
| Tensile Strength | 140-160 MPa | 170-200 MPa |
| HDT (1.8 MPa) | 205°C+ | 250°C+ |
| Moisture Absorption | 1.0-1.5% | 0.8-1.2% |
Selection Summary
Choose Nylon 6 when:
- Impact resistance is critical
- Cost sensitivity is high
- Operating temperatures are moderate
Choose Nylon 66 when:
- Higher mechanical strength is required
- Elevated temperatures are expected
- Dimensional stability is critical
FAQ
When is Nylon 6 vs Nylon 66 — Engineering Plastic Selection Guide a good option?
Nylon 6 vs Nylon 66 — Engineering Plastic Selection Guide is a good option when fast iteration, complex geometry, low tooling cost, or low-volume production is more important than molded-part unit cost.
What should be checked before choosing Nylon 6 vs Nylon 66 — Engineering Plastic Selection Guide?
Check part size, material properties, surface finish, dimensional tolerance, heat exposure, load direction, and whether post-processing is required.
How does Nylon 6 vs Nylon 66 — Engineering Plastic Selection Guide compare with CNC machining?
3D printing can create complex shapes quickly, while CNC machining is often stronger for precise surfaces, tighter tolerances, and production-grade materials.
What affects the cost of Nylon 6 vs Nylon 66 — Engineering Plastic Selection Guide?
Cost depends on material, build volume, print time, layer height, support removal, finishing, inspection, and the number of parts in the build.
Nylon 6 vs Nylon 66 — Frequently Asked Questions
Is Nylon 66 stronger than Nylon 6?
Yes. Nylon 66 typically offers 15-25% higher tensile strength (80-100 MPa vs 70-85 MPa) due to more crystalline structure.
Which nylon is better for gears?
Both work well. PA6 is preferred for impact-loaded gears due to higher toughness. PA66 is better for high-load, high-temperature applications.
Where can I source quality PA6 and PA66 granules?
Nylonplastic supplies both grades in natural, colored, and reinforced versions. Contact us for samples.
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