POM Acetal (Delrin): High-Stiffness Engineering Thermoplastic for Precision Parts
ASTM D6778 · Published: 2026-06-03 · Updated: July 2026
POM (polyoxymethylene), best known as DuPont Delrin, is an engineering thermoplastic with exceptional dimensional stability, low friction, and high stiffness — making it the standard material for gears, bearings, bushings, conveyor chain links,...
POM (polyoxymethylene), best known as DuPont Delrin, is an engineering thermoplastic with exceptional dimensional stability, low friction, and high stiffness — making it the standard material for gears, bearings, bushings, conveyor chain links, and automotive fuel system components. Its fatigue resistance is the highest of any unfilled thermoplastic.
Quick Facts
| Category | Thermoplastics |
| Standard | ASTM D6778 |
| Density | 1.41 g/cm³ |
| Yield Strength | 66 MPa |
| Tensile Strength | 70 MPa |
Global Equivalents & Cross-Reference
| Alternative Standard / Grade | Action |
|---|---|
| DuPont Delrin | Compare |
| Celcon | Compare |
| Hostaform | Compare |
| Tecaform | Compare |
Related Materials
🧮 Material Weight Calculator
Calculate the weight based on this material's density: 1.41 g/cm³
Frequently Asked Questions
How does acetal compare to nylon for gears?
Acetal offers: (1) lower moisture absorption (0.2% vs 1.5-2.5% for nylon 6) — dimensions remain stable in humid environments; (2) lower friction — gears run with less heat generation; (3) better fatigue resistance. Nylon offers better impact resistance and is generally 20-30% lower cost. For precision gears, acetal is the default choice.
References & International Standards
- ASTM International. Standard Specifications for Steel & Metal Alloys. astm.org
- International Organization for Standardization (ISO). Metallic Materials — Cross-Reference Database. iso.org
- American Iron and Steel Institute (AISI). Steel Grade Designations & Equivalents. steel.org
- European Committee for Standardization (CEN). EN Steel Standards & Numbering System. cencenelec.eu