Nylon vs Delrin (POM) for CNC Parts: Which Plastic to Choose?
Delrin excels in dimensional stability and low friction for precision parts like gears and bearings. Nylon offers better impact resistance and higher temperature performance but absorbs more moisture, causing dimensional changes.
Side-by-Side Property Comparison
| Property | Nylon 66 (PA66) | Delrin (POM / Acetal) |
|---|---|---|
| Tensile Strength | 82 MPa (11.9 ksi) | 70 MPa (10.2 ksi) |
| Yield Strength | 69 MPa (10 ksi) | 65 MPa (9.4 ksi) |
| Hardness | Rockwell R120 | Rockwell M80 |
| Density | 1.14 g/cm³ | 1.42 g/cm³ |
| Machinability Rating | 68/100 | 85/100 |
| Thermal Conductivity | 0.26 W/m·K | 0.31 W/m·K |
| Melting Point | 262 °C | 175 °C |
| Tolerance | ±0.05 mm | ±0.02 mm |
Key Differences
| Property | Nylon 66 (PA66) | Delrin (POM / Acetal) | Winner |
|---|---|---|---|
| Dimensional Stability | Fair (moisture) | Excellent | Delrin |
| Moisture Absorption | 2.5% | 0.25% | Delrin |
| Impact Resistance | Excellent | Good | Nylon |
| Friction Coefficient | 0.30-0.40 | 0.20-0.35 | Delrin |
| Temperature Range | Up to 120°C | Up to 100°C | Nylon |
| Machinability | 68/100 | 85/100 | Delrin |
Which Material Should You Choose?
Choose Nylon 66 (PA66) when:
- Impact-loaded components
- Higher temperature applications (up to 120°C)
- Parts needing better chemical resistance
- Under-hood automotive components
- Structural parts requiring toughness
Choose Delrin (POM / Acetal) when:
- Precision gears and bearings
- Parts with tight tolerances
- Low-friction sliding surfaces
- Humid or wet environments
- Food processing equipment
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