Nylon screws are non-metallic fasteners manufactured from Polyamide 6/6 (PA66) or Polyamide 6 (PA6) engineering thermoplastics. They are the standard specification fastener for assemblies requiring electrical insulation, corrosion resistance, weight reduction, or metal-free construction. Metric sizes M2–M12 are held in standard inventory.
Material Specifications — Nylon 6/6 (PA66)
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| Property | Value | Test Standard |
|---|---|---|
| Tensile Strength | 80 MPa | ISO 527 |
| Flexural Strength | 110 MPa | ISO 178 |
| Flexural Modulus | 2,900 MPa | ISO 178 |
| Compressive Strength | 90 MPa | ISO 604 |
| Elongation at Break | 30–50% | ISO 527 |
| Izod Impact Strength (notched) | 5.5 kJ/m² | ISO 180 |
| Hardness (Rockwell) | R119 | ISO 2039-2 |
| Density | 1.14 g/cm³ | ISO 1183 |
| Continuous Service Temperature | 120°C (248°F) | — |
| Melting Point | 255–260°C | ISO 3146 |
| Heat Deflection Temperature (1.8 MPa) | 66°C | ISO 75 |
| Dielectric Strength | 15–20 kV/mm | IEC 60243 |
| Volume Resistivity | >10¹² Ω·cm | IEC 60093 |
| Water Absorption (24h immersion) | ~1.2% | ISO 62 |
| Water Absorption (equilibrium) | 2.5–3.5% | ISO 62 |
| Flammability Rating | UL94 HB | UL 94 |
| Linear Coefficient of Thermal Expansion | 8 × 10⁻⁵ /°C | ISO 11359 |
Engineering Note — Moisture Absorption: PA66 is hygroscopic. Equilibrium moisture absorption of 2.5–3.5% in humid conditions causes measurable dimensional growth (approximately 0.2–0.3% linear expansion) and reduces stiffness by up to 20% compared to dry-as-moulded values. In continuously wet or submerged service, specify PEEK or PVDF fasteners.
Recommended Tightening Torques — Nylon 6/6
Over-tightening is the primary failure mode for nylon fasteners. Thread stripping occurs before fastener yield due to the relatively low shear strength of PA66 (~50 MPa). Use a calibrated torque driver in all precision assemblies.
| Thread Size | Pitch (mm) | Recommended Torque | Max Torque (do not exceed) |
|---|---|---|---|
| M2 | 0.40 | 0.05 N·m | 0.08 N·m |
| M2.5 | 0.45 | 0.09 N·m | 0.13 N·m |
| M3 | 0.50 | 0.15 N·m | 0.25 N·m |
| M4 | 0.70 | 0.30 N·m | 0.45 N·m |
| M5 | 0.80 | 0.55 N·m | 0.75 N·m |
| M6 | 1.00 | 0.85 N·m | 1.20 N·m |
| M8 | 1.25 | 1.60 N·m | 2.20 N·m |
| M10 | 1.50 | 2.50 N·m | 3.50 N·m |
| M12 | 1.75 | 4.00 N·m | 5.50 N·m |
Torque values are for dry installation in nylon-to-nylon or nylon-to-aluminium interfaces. Reduce by 15–20% for nylon-to-nylon tapped holes to account for thread compliance.
Head Types and Drive Configurations
| Head Type | Drive | DIN / ISO Reference | Typical Application |
|---|---|---|---|
| Pan Head | Phillips / Slotted | DIN 7985 / ISO 7045 | PCB mounting, general panel assembly |
| Hex Head (Full Thread) | Hex Wrench | DIN 933 / ISO 4017 | Structural, high-torque assembly |
| Countersunk Flat Head | Phillips / Slotted | DIN 965 / ISO 7046 | Flush-mount, recessed installation |
| Cheese Head | Slotted | DIN 84 / ISO 1207 | Enclosed spaces, tight-clearance assemblies |
| Binding Head | Slotted | — | Terminal blocks, wire connectors |
| Thumb Screw | Knurled | — | Tool-free, field-adjustable fittings |
| Grub / Set Screw | Hex Socket | DIN 913 / ISO 4026 | Shaft collars, headless internal assembly |
Standard thread form: ISO metric coarse (DIN 13). Fine thread and custom thread forms available on request for OEM applications.
Chemical Resistance Reference
| Medium | Resistance |
|---|---|
| Water (cold and warm) | Good |
| Motor oil, hydraulic oil, grease | good |
| Petrol / Diesel fuel | Good |
| Dilute acids (pH > 4) | Good |
| Dilute alkalis | Good |
| Alcohols (methanol, ethanol, IPA) | Good |
| Concentrated sulfuric acid | Poor — not recommended |
| Concentrated nitric acid | Poor — not recommended |
| Phenol, cresol | Poor — not recommended |
| Chlorinated solvents | Limited — test before specifying |
| Salt water / marine environments | Good |
Material Selection Guide — Nylon vs. Alternative Plastic Fastener Materials
| Material | Tensile Strength | Max Continuous Temp | Moisture Absorption | Dielectric Strength | Best Fit |
|---|---|---|---|---|---|
| Nylon 6/6 (PA66) | 80 MPa | 120°C | ~3% | 15–20 kV/mm | General-purpose electronics, automotive, industrial |
| PEEK | 100 MPa | 180°C | <0.5% | 20 kV/mm | Harsh/wet environments, aerospace, medical |
| Polycarbonate (PC) | 60 MPa | 120°C | ~0.4% | 15 kV/mm | Transparent enclosures, optical assemblies |
| PVDF | 55 MPa | 150°C | <0.04% | 10 kV/mm | Semiconductor fab, aggressive chemical environments |
| Polypropylene (PP) | 35 MPa | 100°C | <0.02% | 25 kV/mm | Low-load, acid/alkali-heavy applications |
| PTFE | 20–30 MPa | 260°C | <0.01% | 20 kV/mm | Extreme temperature, chemically inert requirements |
Typical Applications
Electronics and Electrical Engineering — PCB standoffs and mounting screws, transformer core assembly, switchgear panels, bus bar isolation, relay housing. Nylon screws prevent short circuits, eliminate galvanic corrosion between dissimilar metals, and reduce EMI coupling. Chemical Processing and Industrial Equipment — Pump housings, valve bodies, pipe flanges, and filtration systems in corrosive media. Nylon provides cost-effective corrosion resistance where stainless steel is over-specified or where ionic contamination of process fluids must be prevented. Medical and Precision Instrumentation — MRI-compatible enclosures, diagnostic device assemblies, and laboratory instruments require fully non-ferromagnetic fasteners. Nylon screws are autoclave-stable up to 121°C (standard gravity cycle) making them compatible with basic steam sterilisation protocols. Automotive — Interior trim panels, sensor brackets, EV battery pack enclosures, and underhood assemblies where resistance to fuels, oils, and coolants is required alongside weight reduction targets. Renewables and Outdoor Electrical — Solar panel junction boxes, outdoor distribution enclosures, and mounting sub-assemblies. Specify UV-stabilised PA66 grade for applications with direct solar exposure exceeding 1,000 hours annually.
Frequently Asked Questions
What is the difference between Nylon 6 and Nylon 6/6 screws? Both are polyamide materials with similar performance profiles. PA66 (Nylon 6/6) has higher stiffness (~2,900 MPa flexural modulus vs ~2,600 MPa for PA6), better dimensional stability, and slightly higher heat deflection temperature. PA6 offers better impact resistance and is easier to machine for custom components. For standard fastener applications, PA66 is the default specification. At what temperature do nylon screws fail? PA66 screws maintain structural integrity up to approximately 120°C in continuous service. At 150°C, creep accelerates and clamping force will reduce over time. At temperatures above 180°C, thermal degradation begins. For sustained elevated temperature applications, specify PEEK fasteners (continuous service to 180°C). How does moisture affect the mechanical performance of nylon screws? Moisture plasticises the PA66 polymer matrix, reducing tensile strength and stiffness while increasing elongation and toughness. At equilibrium moisture content (~3%), flexural modulus drops approximately 20% and tensile strength reduces by 10–15% compared to dry-as-moulded values. Dimensional growth of 0.2–0.3% occurs linearly. For close-tolerance assemblies in humid environments, account for this dimensional change in bore and clearance design. Can nylon screws be used in outdoor UV-exposed applications? Standard PA66 has only moderate UV resistance. After prolonged UV exposure, surface chalking and embrittlement occur, reducing impact strength. For outdoor applications, specify UV-stabilised or UV-resistant grade PA66 with carbon black or UV absorber additives. Alternatively, PVDF or PP screws offer inherently strong weathering resistance. Are nylon screws compatible with metal nuts? Yes. Nylon screws thread correctly with metric DIN-standard steel, stainless steel, brass, and aluminium nuts. Use a calibrated torque driver and apply recommended torque values above — metal nuts are rigid and provide no compliance buffer, making it easier to over-stress the nylon thread. For vibration-resistance without nylon-insert locknuts, apply a thread-locking compound rated for plastics. What is the voltage rating for nylon screws used in electrical isolation? The dielectric strength of PA66 is 15–20 kV/mm. For a standard M4 pan head screw (approximately 7 mm thread engagement length), the insulation is more than sufficient for low and medium voltage applications. Always consult IEC 60664 clearance and creepage distance requirements for your specific application voltage and pollution degree — the fastener material alone does not define the full insulation system. Do nylon screws require lubrication during installation? No lubrication is required for standard installations. PA66 has inherent low-friction surface properties. If installation torque is higher than expected due to tight tolerances or a long engagement length, a small amount of dry PTFE lubricant (not oil-based) is acceptable and will not degrade the electrical insulation properties. What standards are your nylon screws manufactured to? Standard stock conforms to DIN 933 (hex head), DIN 7985 (pan head Phillips), DIN 965 (countersunk), and DIN 84 (cheese head) dimensional standards. Thread tolerances are to ISO 965-1 (6g tolerance class). Material certification and RoHS compliance documentation are available on request. Can nylon screws be used in food contact or cleanroom environments? Standard PA66 is not FDA-compliant. For food contact or pharmaceutical cleanroom applications, specify screws manufactured from FDA-compliant nylon grades or alternative materials such as PVDF or natural (undyed) PP. Confirm the specific regulatory standard required (FDA 21 CFR, EU 10/2011, USP Class VI) with your supplier before specifying.
For tool-free panel fastening, our nylon rivets offer the same insulation benefits without threads.
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