PEEK vs Delrin (POM): Engineering Plastics Comparison for CNC
Delrin is the cost-effective workhorse for precision mechanical parts with low friction. PEEK is the premium choice for extreme temperatures, chemical resistance, and aerospace/medical applications where its 10x higher cost is justified.
Side-by-Side Property Comparison
| Property | PEEK (Polyether Ether Ketone) | Delrin (POM / Acetal) |
|---|---|---|
| Tensile Strength | 100 MPa (14.5 ksi) | 70 MPa (10.2 ksi) |
| Yield Strength | 91 MPa (13.2 ksi) | 65 MPa (9.4 ksi) |
| Hardness | Rockwell M99 | Rockwell M80 |
| Density | 1.31 g/cm³ | 1.42 g/cm³ |
| Machinability Rating | 60/100 | 85/100 |
| Thermal Conductivity | 0.25 W/m·K | 0.31 W/m·K |
| Melting Point | 343 °C | 175 °C |
| Tolerance | ±0.02 mm | ±0.02 mm |
Key Differences
| Property | PEEK (Polyether Ether Ketone) | Delrin (POM / Acetal) | Winner |
|---|---|---|---|
| Max Temperature | 260°C continuous | 100°C continuous | PEEK |
| Tensile Strength | 100 MPa | 70 MPa | PEEK |
| Machinability | 60/100 | 85/100 | Delrin |
| Cost | ~$100+/kg | ~$5-10/kg | Delrin |
| Chemical Resistance | Exceptional | Good | PEEK |
| Dimensional Stability | Good | Excellent | Delrin |
Which Material Should You Choose?
Choose PEEK (Polyether Ether Ketone) when:
- High-temperature environments (>100°C)
- Aggressive chemical exposure
- Medical implants (biocompatible)
- Aerospace structural parts
- Semiconductor cleanroom applications
Choose Delrin (POM / Acetal) when:
- Gears, bearings, and bushings
- Food processing components
- Cost-sensitive projects
- Precision mechanical parts
- General engineering applications
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