PA66 Nylon: Properties, Uses & Cost Guide
Tensile data verified against MatWeb.com database & manufacturer datasheets · Last updated July 2026
Published: 2026-06-08
PA66 unfilled offers higher strength, stiffness, and heat resistance than PA6, making it the preferred nylon for automotive under-hood and industrial mechanical components.Propprose Processability Score (PPS): 8/10 (Challenging) — Based on melt...
Recommended Applications
PA66 Nylon 66 Unfilled is commonly specified for:
⚠ Not Recommended For
PA66 Nylon 66 Unfilled is not recommended for:
- Moisture-critical dimensional applications without post-molding conditioning (nylon absorbs up to 8% moisture, changing dimensions 0.5-2%)
- Strong acid or oxidizing environments (mineral acids attack nylon; use PVDF or PTFE)
- Electrical insulation in humid environments (moisture absorption degrades dielectric properties)
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Selection & Application Guide
Nylon (PA6/PA66) is the workhorse engineering plastic — offering the best balance of mechanical strength, toughness, wear resistance, and cost for general industrial applications. Choose PA66 over PA6 when higher temperature resistance and stiffness are needed; choose PA6 when impact resistance and flexibility matter more. Both absorb moisture significantly (2-3%), which affects dimensions and properties — consider this in your design.
Real-World Applications
Glass-filled PA66 (30% GF) provides the temperature resistance (HDT 255°C at 0.45 MPa), stiffness, and under-hood chemical resistance for engine covers and air intake manifolds at 4-8× lower cost than PEEK.
Cast nylon (PA6) provides quiet operation, inherent lubricity, and wear resistance for gears, sprockets, and bearing surfaces in conveyor and packaging equipment.
PA66 with flame retardant additives meets UL94 V-0 for electrical connectors and terminal blocks at much lower cost than high-temperature alternatives.
PA6/PA66's combination of strength, flexibility, and weatherability makes it the universal material for cable ties, zip ties, and plastic fasteners in construction and electrical installations.
Processing & Cost Considerations
Manufacturing Tips
- Nylon is hygroscopic and must be thoroughly dried before processing (80-100°C for 4-6 hours for PA6, 80°C for 3-4 hours for PA66). Moisture above 0.2% causes splay marks and reduced molecular weight due to hydrolysis. Use dehumidifying dryers for consistent results.
- Nylon's moisture absorption affects dimensions — parts can grow 0.5-1.0% in length after conditioning to 50% RH. Design molds to account for post-molding dimensional changes, or specify condition the parts before critical assembly operations.
- Glass-filled nylons (30% GF) require hardened mold surfaces (P20 or H13 steel) and hardened screw tips due to abrasive wear. Expect 2-3× faster mold wear compared to unfilled nylon processing.
Nylon is among the most affordable engineering plastics at $3-8/kg for unfilled grades and $6-15/kg for glass-filled grades. This 10-30× cost advantage over PEEK makes nylon the default choice for the vast majority of mechanical applications below 120°C. When higher temperature resistance is needed, consider PA46 (Stanyl, $15-25/kg) or PPA ($12-25/kg) before jumping to PEEK.
Technical Properties
| Density | 1.14 g/cm³ |
|---|---|
| Tensile Strength | 80 MPa (dry) |
| Melting Point | 260 °C |
| Shrinkage Rate | 1.5-2.0% |
| Flexural Modulus | 3.0 GPa |
| Hdt | 95 °C at 1.82 MPa |
| Continuous Service Temp | 120 °C |
| Tensile Modulus | 3.0 GPa |
| Yield Strength | 80 MPa |
| Elongation At Break | 60% |
Engineering Tool: Shrinkage & Cost Estimator
Calculate part weight, mold cavity dimensions accounting for shrinkage, and material cost — all locally in your browser.
Equivalents & Cross-References
| Equivalent / Alternate | Action |
|---|---|
| BASF Ultramid A3K | |
| DuPont Zytel 101L | |
| Radici Radilon A |
Frequently Asked Questions
PA66 vs PA6 — when to use which?
PA66: higher strength, stiffness, melting point (260°C vs 220°C), and better creep resistance. PA6: better impact at low temperature, better surface finish, 15-20% lower cost. For automotive engine bay components, PA66 is standard. For consumer goods and general engineering, PA6 is usually sufficient.
What is the difference between PA6 and PA66?
PA66 has a higher melting point (260°C vs 220°C for PA6), higher stiffness, and better chemical resistance. PA6 has better impact resistance, better surface finish, and faster molding cycle times. For most structural applications above 80°C, PA66 is preferred. PA6 is chosen for its toughness and lower cost in less demanding applications.
How does moisture affect nylon properties?
Moisture acts as a plasticizer in nylon — conditioned (50% RH) PA66 has 50% lower tensile strength than dry-as-molded but 2-3× higher impact strength. This means dry nylon is strong but brittle; conditioned nylon is tougher but weaker. Always specify whether mechanical properties are dry or conditioned for your application.
Can nylon be used for food contact?
Yes. Specific PA6 and PA66 grades comply with FDA 21 CFR 177.1500 for food contact. Natural (unpigmented) grades are most commonly certified. Glass-filled and flame-retardant grades may not be compliant — verify with the manufacturer. Nylon is widely used in food processing machinery components.
Is nylon resistant to UV exposure?
Unprotected nylon degrades under UV exposure, losing tensile strength and becoming discolored. For outdoor applications, specify UV-stabilized grades with carbon black or hindered amine light stabilizers (HALS). Carbon black provides the best UV protection but limits color options. HALS allow lighter colors with moderate UV resistance.
What is the difference between extruded and cast nylon?
Extruded nylon (PA6 or PA66) is produced by melt extrusion and has consistent properties. Cast nylon (PA6G, also called MC nylon) is produced by anionic polymerization in a mold, yielding higher molecular weight and better mechanical properties — approximately 20% higher tensile strength and 30% better impact resistance. Cast nylon is used for large-diameter rods, tubes, and custom shapes.
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References & Industry Standards
- ASTM International. Standard Specifications for Engineering Plastics & Thermoplastics. astm.org
- UL Prospector. Plastics & Elastomers Material Database. ulprospector.com
- MatWeb. Material Property Data for Engineering Thermoplastics. matweb.com
- ISO 1043. Plastics — Symbols and Abbreviated Terms. iso.org