Nomex 418
Additive grade
418 = mica-filled corona-resistant aramid paper
Pick for inverter-fed motors and traction windings where partial-discharge (corona) endurance is required.
Values for the 418 condition
Other Nomex grades and fills
Nomex is listed in 8 conditions; see the grade overview at Nomex.
Compare all 8 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Phenolic-coated aramid honeycomb core, 29 kg/m³ | Lightest common grade for radomes, ducts and non-structural interior panels. | — | 0.85 | — | — |
Phenolic-coated aramid honeycomb core, 48 kg/m³ | Standard aerospace/interior sandwich core: best strength-to-weight with good damage tolerance and FST performance. | — | 2 | — | — |
Phenolic-coated aramid honeycomb core, 144 kg/m³ | High-density core for floor panels, hard points and highly loaded sandwich zones. | — | 10 | — | — |
Uncalendered low-density aramid paper | Soft, porous, highly conformable paper for cushioning/impregnation where varnish penetration matters more than dielectric strength. | — | 20 | 8 | — |
993/994 | Rigid 1.5–9 mm board for transformer spacers, barriers and end-frame insulation at class 220. | — | 45 | 6 | — |
418This page Mica-filled corona-resistant aramid paper | Pick for inverter-fed motors and traction windings where partial-discharge (corona) endurance is required. | — | 55 | 7 | — |
410Default Calendered meta-aramid insulation paper | Standard high-density insulating paper for motor slot liners, phase insulation and transformer windings (class 220). | — | 90 | 12 | — |
Aramid-paper/phenolic laminate sheet | Machinable rigid laminate for lightweight FR structural panels, bushings and electrical insulation parts. | — | 140 | 2 | 100 HRM |
What is Nomex 418?
Nomex 418 is Nomex in the 418 grade — pick for inverter-fed motors and traction windings where partial-discharge (corona) endurance is required. Nomex 418 has a tensile strength of 55 MPa (7.98 ksi), weaker than 81% of composite grades. Elongation at break is 7% and the elastic modulus is 3 GPa (0.435 Msi). Nomex 418 has a density of 1 g/cm³ (0.0361 lb/in³), lighter than 81% of composite grades. Its glass-transition temperature is 275°C (527 °F). 410 is the default condition FabDigit quotes; 418 is available on request or by drawing note.
Advantages
- Ductile — tolerates forming and impact — 7%, better than 89% of composite grades
- Lightweight — 1 g/cm³ (0.0361 lb/in³), better than 81% of composite grades
Limitations
- Hard to polish — 10/100, worse than 97% of composite grades
- Absorbs moisture — dry before molding — 4.5%, worse than 95% of composite grades
- Degrades in UV without stabilisers — 25/100, worse than 86% of composite grades
- Low stiffness — 3 GPa (0.435 Msi), worse than 81% of composite grades
- Poor heat conductor — 0.15 W/m·K (0.0867 BTU/hr·ft·°F), worse than 79% of composite grades
Nomex 418 properties
Typical room-temperature values for Nomex 418; 12 are specific to this condition. Other listed values are Nomex reference data and may not represent this condition. Bars are the position among composite grades.
Physical4
Nomex 418 has a density of 1 g/cm³ (0.0361 lb/in³), lighter than 81% of composite grades. Its glass-transition temperature is 275°C (527 °F).
Mechanical4
Nomex 418 has a tensile strength of 55 MPa (7.98 ksi), weaker than 81% of composite grades. Elongation at break is 7% and the elastic modulus is 3 GPa (0.435 Msi).
Thermal8
Nomex 418 is rated for continuous service to 220°C (428 °F). It conducts heat at 0.15 W/m·K (0.0867 BTU/hr·ft·°F), worse than 79% of composite grades. Thermal expansion is 17 µm/m·K (9.44 µin/in·°F).
Electrical5
Nomex 418 is an electrical insulator with a dielectric strength of 24 kV/mm (609.6 V/mil) and a resistivity of 1×10¹⁴ Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (70/100), worse than 64% of composite grades. UV resistance is poor.
Sustainability4
Producing a kilogram of Nomex 418 takes about 260 MJ of energy and emits 11 kg of CO₂ — more than 57% of composite grades. Typical recycled content is 0%.
Manufacturability2
Nomex 418's machinability is fair (45/100, better than 63% of composite grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Nomex 418
Is Nomex easy to machine?
Paper and pressboard die-cut, laser or waterjet cut cleanly; honeycomb core needs razor/serrated blades, high-speed router with sharp carbide or waterjet plus vacuum fixturing to avoid cell crush and fuzzing.
Can Nomex be welded?
Not weldable or heat-sealable (no melting point) — join by adhesive bonding, resin impregnation, stitching or mechanical clamping.
Can Nomex be formed, bent or molded?
Paper and honeycomb are cold-formable/creped to gentle curvature; core is expanded from an HOBE block and phenolic-dipped, and sandwich panels are co-cured or bonded with 120–180 °C film adhesive.
What surface finishes work on Nomex?
Dry the material before bonding or varnish impregnation (hygroscopic); surfaces accept phenolic/epoxy varnish, corona or plasma treatment improves adhesion; no plating or polishing applies.
Nomex chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| mica filleronly in corona-resistant 418-type paper | 0 – 50 | 0 |
| phenolic resin coatingonly in honeycomb core / laminate forms | 0 – 45 | 0 |
| poly(m-phenylene isophthalamide) (meta-afrom m-phenylenediamine + isophthaloyl chloride; paper grades = floc + binder fibrids | balance | — |
Nomex 418 — frequently asked
What is Nomex 418 used for?
Nomex 418 is typically used for honeycomb sandwich cores, firefighter/protective clothing, electrical insulation paper and filtration media. In short: flame-resistant meta-aramid; standard honeycomb core material; class H electrical insulation.
What is the tensile strength of Nomex 418?
Nomex 418 has a typical tensile strength of 55 MPa (7.98 ksi) — weaker than 81% of composite grades. Strength varies by condition: see the 8 listed tempers.
Is Nomex 418 easy to machine?
Reasonably — machinability is rated fair (45/100, better than 63% of composite grades). Paper and pressboard die-cut, laser or waterjet cut cleanly; honeycomb core needs razor/serrated blades, high-speed router with sharp carbide or waterjet plus vacuum fixturing to avoid cell crush and fuzzing.
Can Nomex 418 be welded?
Not weldable or heat-sealable (no melting point) — join by adhesive bonding, resin impregnation, stitching or mechanical clamping.
What surface finishes work on Nomex 418?
Dry the material before bonding or varnish impregnation (hygroscopic); surfaces accept phenolic/epoxy varnish, corona or plasma treatment improves adhesion; no plating or polishing applies.
Can Nomex 418 be formed, bent or molded?
Paper and honeycomb are cold-formable/creped to gentle curvature; core is expanded from an HOBE block and phenolic-dipped, and sandwich panels are co-cured or bonded with 120–180 °C film adhesive.
What is the maximum service temperature of Nomex 418?
Nomex 418 is rated for continuous use to about 220°C (428 °F), and briefly to 300°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- Nomex 410 / 411 / 418 Technical Data Sheets — DuPont (2022)
- HexWeb HRH-10 Aramid Fibre/Phenolic Honeycomb Product Data — Hexcel (2020)
- Nomex Brand Fiber Technical Guide — DuPont (2021)
- IEC 60216 / IEC 60641 insulation thermal classification (class 220) — IEC (2013)
- ASTM D202 — Testing Insulating Paper — ASTM (2017)
- Engineered Materials Handbook Vol. 2 — Engineering Plastics — ASM International (1988)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.