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When designing plastic gears, PA66 and POM are two widely used engineering plastics. Many engineers struggle to choose between them. They have different advantages in wear resistance, impact toughness, dimensional stability and fatigue performance. There is no universal "better" material, only the one that fits your working conditions.

Core Advantages

🟦 PA66 (for gear application)

  • - Excellent impact toughness, withstand impact during start-stop cycles
  • - High fatigue strength, stable under long-term reciprocating motion
  • - Inherent self-lubricating property
  • - Available with glass fiber reinforcement for higher rigidity and heat resistance

⚪ POM (for gear application)

  • - High hardness and rigidity, resistant to surface deformation
  • - Outstanding wear resistance, superior self-lubrication compared to PA66
  • - Ultra-low water absorption, stable dimension under humidity change
  • - Low friction coefficient for smooth running

Performance Comparison

1. Wear resistance: POM wins. POM is harder with a lower friction coefficient, better for dry running without lubrication.
2. Impact toughness: PA66 wins. PA66 is tough to handle start-stop and impact loads; POM is relatively brittle.
3. Dimensional stability: POM wins. Hardly absorbs water, dimensions remain stable regardless of humidity. PA66 swells after moisture absorption, risky for precision gears.
4. Long-term fatigue resistance: PA66 wins. Higher fatigue strength for long-time reciprocating operation.
5. Heat resistance: PA66 slightly wins. Higher heat deflection temperature, while the gap with POM is limited.
6. Cost & processing: Comparable. Depends on specific grades and modification formulas.

Selection Guide

Choose POM for high-speed, precision gears requiring stable dimensions and no lubrication.
Choose PA66 for high-load, frequent start-stop, impact working scenarios where lubrication is available.
If both wear resistance and toughness are required: use toughened POM or glass-filled PA66.
If both materials are feasible, select based on quotation after confirming working conditions.