Nylon (Polyamide)

About Nylon (Polyamide)

Nylon, or Polyamide (PA), is one of the most important engineering thermoplastics, prized for its outstanding balance of mechanical strength, stiffness, toughness, chemical resistance, and thermal performance. The two most widely used commercial grades are PA6 (Nylon 6) and PA66 (Nylon 6,6), both offering excellent fatigue resistance, low coefficient of friction, and good wear properties that make them ideal replacements for metal in load-bearing and moving-part applications.

PA66 offers slightly higher melting point (262°C vs. 220°C for PA6), higher stiffness, and better short-term heat resistance, making it the preferred choice for demanding automotive under-hood and high-temperature industrial applications. PA6 offers better impact strength, surface finish, and processability, and is commonly used in consumer goods, cable ties, and general industrial components.

Nylon is hygroscopic — it absorbs moisture from the atmosphere, which directly affects its mechanical properties and dimensional stability. Proper drying before injection molding is essential (typically 80°C for 4–8 hours for PA6; 80–90°C for 4–8 hours for PA66) to avoid hydrolytic degradation, splay, and reduced molecular weight. Conditioned (moisture-equilibrated) nylon parts exhibit significantly higher impact resistance than dry-as-molded parts.

Nylon for Injection Molding

Nylon is one of the most widely injection molded engineering resins. Its relatively low melt viscosity (especially PA6) enables fast fill of thin-wall and complex geometries. However, nylon's semi-crystalline nature means it has a sharp crystallization point and higher shrinkage (1.0–2.0% unfilled; 0.3–0.7% with 30% glass fiber) than amorphous resins — requiring careful tool design and process control to manage warpage and dimensional tolerances.