Nylon 66 (PA66) Precision CNC Machining & Moisture Control
Nylon 66 (Polyamide) is a high-toughness engineering thermoplastic with excellent wear resistance and vibration damping, requiring strict environmental control to prevent moisture-induced dimensional expansion.
Engineering Specifications & Parameters
Density
1.14 g/cm3
Melting Point
260 C (500 F)
Tensile Strength
85 MPa (12,300 psi)
Machinability Rating
85% (Very Good, Ductile Chip)
Dimensional Swelling Factor
0.2% - 0.3% linear expansion per 1% moisture
Moisture Absorption (Equilibrium)
2.8% @ 50% Relative Humidity
Hygroscopic Behavior & Dimensional Stability
PA66 is strongly hygroscopic, capable of absorbing 2.5% to 8.5% atmospheric moisture by weight, which increases part dimensions by 0.5% to 0.7%.
CNC Milling & Lathe Best Practices
Tooling: Razor-sharp single-flute or 2-flute polished carbide end mills with 15-degree positive shear rake.
Cooling: Clean dry air blast. Water-based coolants cause accelerated post-machining swelling.
Deburring: High ductility creates persistent exit burrs; cryogenic deburring or manual razor trimming is recommended.
How do you maintain tight +/-0.02mm tolerances on PA66 Nylon parts?
Pre-condition raw stock at ambient operating humidity before machining, use sharp cutters to prevent frictional heat, and measure in a humidity-controlled environment.
What causes PA66 to melt and gum up during drilling?
High friction from dull drills with standard 118-degree points; use polished 90-degree plastic drills with wide open parabolic flutes.
