Aramid Paper (Nomex®)
Nomex® aramid paper is the material of choice when transformer winding insulation, motor slot liners, or high-voltage phase barriers must retain dielectric integrity and dimensional stability at elevated temperatures where standard cellulose papers degrade. Its meta-aramid chemistry provides continuous thermal resistance to 220°C with UL thermal class H rating and inherent flame resistance, making it the motor and transformer industry’s standard electrical insulation substrate. H-O Products carries the full range of Nomex® families, from standard 410 and calendered 411 grades through high-density 414, meta-para blend 464, and structural pressboard 818, and converts them to customer specification.
Nomex® 410 Aramid Electrical Insulation Paper
Nomex® 410 is an aramid insulation paper offering high inherent dielectric strength, mechanical toughness, flexibility, and resilience, available in 10 thicknesses ranging from 0.05 mm to 0.76 mm (2 mil to 30 mil). It is recognized by Underwriters Laboratories as a 220°C insulating material and retains useful mechanical and dielectric properties from cryogenic temperatures (–196°C) up to 400°C. Nomex® 410 is used in almost every known electrical sheet insulation application.
Key Properties
- Tensile Strength (0.25 mm/10 mil): MD 296 N/cm, XD 161 N/cm — ASTM D828
- Elongation (0.25 mm/10 mil): MD 22%, XD 18% — ASTM D828
- Dielectric Strength, AC Rapid Rise (0.25 mm/10 mil): 845 V/mil (33 kV/mm) — ASTM D1491
- Temperature Resistance: Recognized 220°C insulating material (UL); retains useful properties from –196°C to 400°C
- Thickness Range: 0.05–0.76 mm (2–30 mil), 10 standard grades — ASTM D3741
- Density (0.25 mm/10 mil): 0.96 g/cc
Nomex® Type 411 Uncalendered Aramid Insulation Paper
Nomex® Type 411 is the uncalendered precursor of Nomex® Type 410, available in five thicknesses from 0.13 mm to 0.58 mm (5 mil to 23 mil) with a density of 0.3, giving it correspondingly lower electrical and mechanical properties and higher bulk than Type 410. It is used in applications such as motor phase insulation and transformer coil end filler where high bulk and conformability are of prime importance, and its increased impregnability and saturability make it suitable for cast resin turn and layer insulation.
Key Properties
- Tensile Strength (0.25 mm/10 mil): MD 35 N/cm, XD 20 N/cm — ASTM D828
- Elongation (0.25 mm/10 mil): MD 3.4%, XD 5.2% — ASTM D828
- Dielectric Strength, AC Rapid Rise (0.25 mm/10 mil): 240 V/mil (9 kV/mm) — ASTM D149
- Temperature Resistance: Recognized 220°C insulating material; Limiting Oxygen Index 28.5% at room temperature (0.13 mm/5 mil)
- Thickness Range: 0.13–0.58 mm (5–23 mil), 5 standard grades — TAPPI-411
- Density (0.25 mm/10 mil): 0.31 g/cc
Nomex® Type 414 High Density
Nomex® Type 414 is designed for applications requiring a strong, yet flexible and conformable sheet. It is electrically and thermally similar to Nomex® Type 410, but is calendered under different conditions to provide its unique properties, and is produced in five thicknesses from 0.09 mm to 0.38 mm (3.4 mil to 15 mil) with a density from 0.9 to 1.0. Type 414 was designed for use as slot insulation in hand-wound motors and for linear wrapping of wire.
Key Properties
- Tensile Strength (0.25 mm/10 mil): MD 229 N/cm, XD 119 N/cm — ASTM D828
- Elongation (0.25 mm/10 mil): MD 13%, XD 16% — ASTM D828
- Dielectric Strength, AC Rapid Rise (0.25 mm/10 mil): 740 V/mil (29 kV/mm) — ASTM D149
- Temperature Resistance: Recognized 220°C insulating material; reacts similarly to temperature changes up to 220°C as Type 410
- Thickness Range: 0.09–0.38 mm (3.4–15 mil), 5 standard grades — ASTM D374
- Density (0.25 mm/10 mil): 0.95 g/cc
Nomex® Laminate Type NMN Aramid Paper / Polyester Film Triplex Laminate
Nomex® Laminate Type NMN is a triplex laminate constructed of calendered Nomex® paper bonded to polyester film with a proprietary high-temperature adhesive system, designed not to delaminate or blister at high temperatures. The polyester film core contributes high dielectric strength along with good initial tear strength and tensile properties, while the calendered Nomex® paper outer layers provide long-term thermal stability and improved propagation tear strength. Type NMN is recognized in UL insulation systems for both Class F and Class H motors and generators.
Key Properties
- MD Tensile Strength (NMN 3-5-3, 0.012 in): 175 lb/in width — ASTM D882
- XD Tensile Strength (NMN 3-5-3, 0.012 in): 150 lb/in width — ASTM D882
- Dielectric Strength (NMN 3-5-3, 0.012 in): 17,000 volts — ASTM D149
- MD/XD Tear Strength (NMN 3-5-3, 0.012 in): 26 lbs / 18 lbs — ASTM D1004
- Thickness Range: 0.007–0.021 in nominal across 11 standard constructions — ASTM D374
- Temperature Rating: UL-recognized insulation system for Class F and Class H motors and generators
Nomex® 818 Calendered Aramid-Mica Insulation Paper
Nomex® 818 is a calendered blend of aramid and mica paper designed for high-voltage applications, including motor conductor and coil wrap, transformer ground and layer insulation. It offers high inherent dielectric strength (700–1,000 V/mil) and increased voltage endurance compared to Nomex® 410 when subjected to corona attack. Nomex® 818 is available in five thicknesses ranging from 0.08 mm to 0.25 mm (3 mil to 10 mil).
Key Properties
- Tensile Strength (0.13 mm/5 mil): MD 52 N/cm, XD 38 N/cm — ASTM D828
- Elongation (0.13 mm/5 mil): MD 3.0%, XD 3.4% — ASTM D828
- Dielectric Strength, AC Rapid Rise (0.13 mm/5 mil): 890 V/mil (35.0 kV/mm) — ASTM D149
- Temperature Resistance: Recognized 220°C insulating material; retains ≥50% tensile strength and elongation up to 250°C
- Thickness Range: 0.08–0.25 mm (3–10 mil), 5 standard grades — ASTM D374
- Density (0.13 mm/5 mil): 1.13 g/cc
