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Nomex® lacing cords are high-temperature, flame-resistant tying materials used to secure wire bundles in aerospace, defense, space, and high-reliability electronics.
Nomex corresponds to MIL-T-43435 Type V and the updated commercial description A-A-52084.
Nomex is selected when a harness must remain stable under heat, vibration, electrical load, and fire-risk conditions.
1. What Nomex Lacing Cord Is
Nomex is a meta-aramid fiber. It does not melt; instead, it chars when exposed to flame.
From Western Filament’s published data, Nomex lacing tape has an approximate operating range of –100°F (–73°C) to 500°F (260°C).
The aerospace research confirms Nomex is used where flame resistance and electrical stability are required.
2. Why Engineers Use Nomex
- Flame-resistant and self-extinguishing
- High strength for its size
- Good electrical insulation
- Low smoke / low toxicity
- Stable at high temperature
- Good resistance to oils, fuels, hydraulic fluids
Nomex remains a preferred material for:
- Aircraft avionics harnesses
- Engine-bay wiring (within approved zones)
- Satellites and space vehicles
- Defense electronics
- High-temperature industrial systems
3. Fast Spec Summary — Nomex Type V / A-A-52084
| Attribute | Description |
| Spec | MIL-T-43435 Type V (legacy) → A-A-52084 (current) |
| Material | Meta-aramid Nomex® |
| Form | Flat braided lacing tape |
| Typical Sizes | .040″, .050″, .060″, .085″, .110″, .200″ (manufacturer dependent) |
| Operating Range | –100°F to +500°F (–73°C to +260°C) |
| Flame Behaviour | Self-extinguishing; chars instead of melting |
| Finish Options | A, B, C, E, F, G (see table below) |
| Notes | Width, tensile, and finish vary by manufacturer. Verify before use. |
4. Finishes (Documented Manufacturer Options)
From Western Filament’s Nomex data:
- A — No coating (lowest outgassing, cleanest surface)
- B — Wax (best knot holding)
- C — Elastomer (added stiffness; flame behavior)
- E — Vinyl (handling / abrasion support)
- F — Silicone resin (thermal stability)
- G — Liquid nylon (surface stability; knot consistency)
Finish selection affects:
- Knot performance
- Temperature behavior
- Handling characteristics
- Space/outgassing acceptance
5. Available Sizes (Manufacturer-Documented Examples)
| Size | Typical Width | Typical Break Strength | Common Use |
| Size 1 | ~.200″ | ~135 lb | Large aircraft bundles |
| Size 2 | ~.110″ | ~80 lb | Standard avionics wiring |
| Size 3 | ~.085″ | ~50 lb | Flight-deck bundles |
| Size 4 | ~.060″ | ~25 lb | Lighter electronic looms |
| Size 5 | ~.050″ | ~15 lb | Compact wiring |
| Size 6 | ~.040″ | ~15 lb | Precision electronics |
Important:
Values above come from Western Filament’s catalog and are manufacturer-specific.
Always match size/finish against your approved datasheet.
6. Installation (NASA-STD-8739.4 Workmanship)
NASA-STD-8739.4 describes the lacing methods used with Nomex:
- Spot ties
- Continuous spiral lacing
- Double-cord lacing
- Starting and finishing knots
These methods support reliable strain relief and bundle stability.
7. Outgassing & Spaceflight Notes
From the aerospace lacing research:
- PTFE and PTFE-glass cords are preferred for hard-vacuum applications.
- Nomex may be used, but finish selection matters.
Typical industry behavior (requires verification):
- Uncoated Nomex (Finish A) or specific low-outgassing finishes may be required for spacecraft harnesses.
8. Cross-Reference Guidance
Manufacturers label Nomex Type V products differently (e.g., Western Filament, Breyden, Techflex).
Cross-references require verification using:
- OEM drawings
- Spec tables
- Manufacturer datasheets
Never assume equivalence without documentation.
9. Safety & Substitution Notes
- Do not substitute Nomex where PTFE-glass is required for extreme temperature or flame duration requirements.
- Ensure size, tensile class, and finish match the engineering drawing.
- Confirm acceptance in high-heat, fuel-rich, or vacuum environments.
- Verify finish compatibility with knotting method.
10. Comparison to Other Materials
| Material | Heat | Flame Behaviour | Notes |
| Nomex | High (to ~260°C) | Self-extinguishing | Best general-purpose aerospace lacing |
| PTFE | Excellent | Non-flammable | Slick surface; knot technique required |
| PTFE-Glass | Extreme | Incombustible | For highest-temperature zones |
| Polyester | Medium | Burns | Aviation-friendly but not for high heat |
| Nylon | Lower | Melts | General purpose only |
See full material comparison guide →
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