Nylon 66 (PA66)

Nylon 66 (PA66) is a semi-crystalline polyamide and one of the most used engineering plastics. Dry as molded and unfilled, it runs about 12,000 psi (83 MPa) tensile, melts at 500 °F (262 °C), and resists wear, oils and fuels. It absorbs about 2.5% water at 50% humidity, which lowers stiffness, so design with conditioned properties.

Price a part in PA66

ISO 1043: PA66
ASTM: D4066 / D6779 (polyamide molding materials)
Trade names: Zytel 101, Ultramid A3K, Vydyne

How does it compare?

Typical room-temperature values for PA66, against all 48 materials in the library.

Tensile strength: 83 MPa36th pct
Density: 1.14 g/cm³11th pct
Max service temp: 100 °C10th pct
Relative cost: $$$$$

Density: 1.14 g/cm³ · 0.0412 lb/in³
Tensile strength: 83 MPa · 12.0 ksi
Elastic modulus: 3.1 GPa · 0.4 Msi
Hardness: Rockwell R120
Max service temperature: 100 °C · 212 °F
Melting point: 262 °C · 504 °F
Thermal conductivity: 0.25 W/m·K

When should you use PA66?

Strengths

High strength and toughness for an unfilled plastic
Good wear resistance and low friction for gears, bushings and slides
Resists oils, greases, fuels and most solvents
High melt point of 500 °F (262 °C) tolerates solder and under-hood heat
Fast-cycling semi-crystalline molding

Watch for

Absorbs about 2.5% moisture at 50% RH and up to about 8% saturated, changing size and stiffness
Attacked by strong acids, phenols and zinc chloride
Higher shrink than amorphous plastics, about 1.5–2% unfilled; warps with uneven walls
Must be molded dry, below about 0.2% moisture

Typical parts

Gears and bushings
Cable ties and clips
Rollers and wear pads
Power tool components
Fasteners and spacers
Electrical connectors

How PA66 is made into parts

Cost, finishes and design rules for each process in this material.

What does a part in PA66 cost?

A representative part, injection molding. Raw material at about $3.80/kg is one line of it; process time and tooling usually matter more.

Housing · Injection molding

$2.52per part, all-in, at 10,000 pcs

Order total $25,207

Tooling: $17,029; one-time, spread over the order
Piece price: $0.78; before setup + tooling
Lead time: 6–9 weeks; to first production

Size

Drag a row to adjust · click to type

Length

140

Width

90.0

Wall

2.20

Material

Design checks pass

Open in builder

Budgetary estimate for a representative part. Firm quotes come from principals after drawing review.

Finishes

Compared head to head

PA66 questions

Does nylon absorb water?

Yes. PA66 absorbs about 2.5% water at 50% relative humidity and up to about 8% when saturated. Moisture makes it tougher but can cut stiffness by more than half and grows parts roughly 0.5–0.7%. Design with conditioned data, not dry-as-molded values.

Nylon 6 vs nylon 66?

PA66 melts higher (500 °F / 262 °C vs about 428 °F / 220 °C), is slightly stiffer and absorbs a little less moisture. PA6 is tougher, molds with a better surface and costs slightly less. Both are common; PA66 is preferred for heat.

Is nylon good for gears?

Yes, for light to moderate loads and quiet running. Nylon gears can run without lubrication, dampen noise and mate well with steel. Acetal is the better call where moisture would change tooth dimensions.

Nylon vs acetal (Delrin)?

Acetal is stiffer, absorbs almost no moisture and holds tighter tolerances. Nylon is tougher, handles higher temperatures and resists abrasion better. Use acetal for precision parts, nylon for impact and heat.