I. How to choose materials
1. General-purpose economical PA66 (Nylon 66, glass fiber reinforced GF30 preferred) ✅ Highest shipment volume
Applications: PCB board isolation, electrical control boxes, low-voltage electrical equipment, new energy wiring harness fixing, automation light-load insulation connections
- Advantages: Stable insulation, high cost-effectiveness, mature molding process, UL94 V2 flame-retardant version available, standard DIN/ISO full specifications in stock (M2–M12)
- Disadvantages: Water absorption is the biggest concern; volume resistivity decreases in humid environments, and creep will occur under long-term continuous stress; continuous temperature resistance 80–105℃, not suitable for high-temperature and strong acid conditions
- Reminder: For long-term outdoor exposure, always choose UV-stabilized modified PA66; ordinary nylon is prone to aging and becoming brittle.
2. Medium to High Temperature + Chemical Resistance: PPS (Polyphenylene Sulfide)
Applications: Inverters, charging pile interiors, weakly corrosive chemicals, 150–200℃ operating conditions
- Advantages: Extremely low water absorption, insulation almost unaffected by humidity, flame retardant UL94 V0, creep resistance far superior to nylon, oil and solvent resistant
- Disadvantages: Higher cost than nylon, more brittle, assembly torque cannot be as tight as steel bolts, prone to thread breakage
3. High-end and demanding operating conditions: PEEK (Polyetheretherketone)
Applications: Semiconductor equipment, aerospace, medical, oil and gas well drilling, high frequency and high voltage, continuous high temperature up to 240℃
- Advantages: High dielectric strength, virtually non-absorbent, extremely strong creep resistance, resistant to most acids and alkalis, non-magnetic, suitable for MRI/sensor interference prevention
- Disadvantages: Very expensive, generally only used in key local locations, not suitable for large-scale general insulation projects
4. High-voltage electrical sheet insulation components: G10 / FR4 / G11 epoxy glass cloth laminated rods (machined insulating screws, insulating posts)
Applications: High-voltage switchgear, busbar isolation, power equipment, medium and high voltage insulating tie rods (not injection molded screws)
- Advantages: Excellent dielectric strength, strong high-voltage insulation stability, G11 has higher temperature resistance than G10
- Disadvantages: Can only be machined, long lead time, cannot be made into very small M2/M3 fine threads, average impact toughness
5. Strong acids and alkalis at low temperatures: PP / PVDF / PTFE
PP: Suitable for electroplating baths, water treatment, and weak acids and alkalis; low upper temperature resistance (≤80℃); weak strength; only suitable for light loads.
PTFE: Extremely chemically resistant and low friction, but soft and prone to creep; unsuitable for continuous tightening under stress; generally used as insulating gaskets, rarely used alone for bolts.
II. Four core parameters that must be checked when selecting a product
1. Dielectric Strength (kV/mm): Low-voltage electronics ≥10kV/mm; high-voltage electrical grades require even higher values. See ASTM D149 test report.
2. Continuous Operating Temperature: Do not only consider short-term heat distortion temperature; select based on continuous load temperature.
3. Creep: The leading cause of failure in plastic insulation components. After prolonged tightening, the tensile force gradually loosens. Do not use ordinary nylon for high loads.
4. Environmental Medium: Humidity, salt water, UV radiation, oil, and chemicals directly determine whether nylon can be used.
III. Common Standards and Specifications
Thread: Metric M / UNC UNF; Head: Internal Hex, External Hex, Pan Head, Countersunk Head, Standoff/Spacer
Standard References: DIN933, ISO4017, ISO4032; Compliance: RoHS, UL Flame Retardant Rating, IEC61010 Electrical Safety Standard
IV. Concise Selection Comparison Table
| Material | Continuous Temp | Moisture Sensitivity | Chemical Resistance | Typical Use | Cost |
|---|---|---|---|---|---|
| PA66 GF30 | 80–105℃ | Medium | Fair | PCB, control cabinet, low voltage | Low |
| PPS | 180–200℃ | Very low | Good | Charging pile, inverter | Mid |
| PEEK | 240–260℃ | Very low | Excellent | Semiconductor, aerospace | High |
| G10 / G11 | 130–155℃ | Low | Fair | High voltage busbar, power cabinet | Mid |
| Alumina Ceramic | Up to 1400℃ | None | Excellent | Furnace, high heat chamber | High |
FAQ
Q1: Can nylon insulated screws be used outdoors?
A: Ordinary PA66 is not recommended for long-term outdoor use. Water absorption and UV aging will reduce insulation and strength. For outdoor use, choose UV-stabilized PPS or glass fiber modified weather-resistant grades.
Q2: Can insulated fasteners be tightened to the same torque as steel bolts?
A: Absolutely not. Plastics and laminated materials have low modulus; excessive torque will directly cause stripping and cracking. A separate assembly torque table needs to be provided to the customer.
Q3: For high-voltage projects, should G11 or PEEK be prioritized?
A: For medium- and high-voltage power isolation and large-diameter tie rods, G11 epoxy laminates are preferred; for confined spaces, high temperatures, and simultaneous mechanical loads, PEEK is preferred.
If you cannot confirm which insulating fastener fits your voltage, temperature and chemical environment, send us your assembly drawing and working condition. We provide material recommendation, torque guide and test certificates for bulk order. Custom non-standard thread and head types available.
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