NMN insulating paper has good mechanical properties such as tensile strength and edge tear resistance as well as good electrical strength.
NMN insulating paper is mainly suitable for F, H transformers, motors, electrical appliances special parts for slot, turn and liner insulation, in addition to transformers or other electrical appliances can also be used as interlayer insulation.
Heat resistance class H (180°C).
Technical parameters:
Indicator Name（6640) | Unit | Indicator value | |||||||||||
Nominal thickness | mm | 0.14 | 0.15 | 0.17 | 0.19 | 0.22 | 0.24 | 0.26 | 0.31 | 0.37 | 0.41 | 0.47 | |
Thickness tolerance | mm | ±0.021 | ±0.022 | ±0.022 | ±0.022 | ±0.022 | ±0.024 | ±0.026 | ±0.031 | ±0.037 | ±0.041 | ±0.047 | |
Quantitative | g/㎡ | 140±17 | 150±18 | 170±20 | 200±24 | 230±27 | 270±32 | 305±36 | 360±43 | 450±54 | 515±61 | 590±70 | |
Nominal film thickness | μm | 23 | 36 | 50 | 75 | 100 | 125 | 150 | 188 | 250 | 300 | 350 | |
Tensile strength | No bending in the longitudinal direction | N/10mm Width | ≥100 | ≥150 | ≥150 | ≥170 | ≥190 | ≥220 | ≥240 | ≥270 | ≥330 | ≥370 | ≥400 |
After bending laterally | ≥80 | ≥90 | ≥90 | ≥105 | ≥120 | ≥150 | ≥180 | ≥200 | ≥300 | ≥330 | ≥350 | ||
Longitudinal bending | ≥80 | ≥80 | ≥90 | ≥100 | ≥110 | ≥130 | ≥170 | ≥200 | ≥250 | ≥300 | ≥300 | ||
Horizontal bending | ≥50 | ≥70 | ≥70 | ≥90 | ≥100 | ≥120 | ≥150 | ≥150 | ≥200 | ≥230 | ≥250 | ||
Elongation | No bending in the longitudinal direction | % | ≥50 | ≥20 | |||||||||
After bending laterally | ≥20 | ≥25 | |||||||||||
Breakdown voltage | No bending | ≥6.0 | ≥7.0 | ≥8.0 | ≥11.0 | ≥12.0 | ≥14.0 | ≥16.0 | ≥19.0 | ≥23.0 | ≥25.0 | ≥28.0 | |
After bending | ≥5.0 | ≥6.0 | ≥7.0 | ≥9.0 | ≥10.0 | ≥12.0 | ≥14.0 | ≥15.0 | ≥18.0 | ≥19.0 | ≥20.0 | ||
Layering | -- | No delamination, no bubbles or other defects | |||||||||||
Subject to heat (180 ± 2°C, 10 min or as agreed upon by the supplier and the buyer) | -- | No delamination, no bubbling, no glue dripping | |||||||||||
Stiffness | N | Pending | |||||||||||
Long-term heat resistance Temperature index (TI) | -- | ≥155 | |||||||||||
Polyester Film Polyaramid Fiber Paper Composite Material, commonly known in the electrical insulation industry as 6640 NMN, is a premium-grade laminated composite designed to provide exceptional insulation performance in demanding electrical applications. It is made by bonding polyamide paper (aramid paper) to both sides of a high-quality polyester (PET) film, forming a three-layer sandwich structure: N–M–N, where N represents aramid insulating paper and M represents polyester film. Because of its outstanding combination of mechanical strength, thermal resistance, dielectric strength, and long-term durability, 6640 NMN has become one of the most widely used insulation materials for Class F and Class H electrical systems.
This material is engineered to deliver highly stable insulation performance under elevated temperatures, mechanical stress, and harsh operational environments. With superior tear resistance, excellent flexibility, high dielectric breakdown strength, and long-term thermal endurance, NMN insulation provides a reliable solution for electric motors, transformers, coils, and various electronic components. The polyester film at the center layer contributes enhanced mechanical strength and dielectric properties, while the aramid fiber paper layers offer high thermal resistance, excellent impregnability with varnish, and superior compatibility with resin systems.
As modern electrical equipment continues to evolve toward higher efficiency and higher power density, insulation materials such as 6640 NMN play an increasingly critical role. This composite is used extensively in slot insulation, phase insulation, liner insulation, turn-to-turn insulation, gasket insulation, and thermal shielding across multiple industries. Whether used in high-voltage motors, generators, power transformers, EV motors, inverter-controlled systems, home appliances, compressors, or industrial power tools, NMN provides robust protection while enhancing device reliability and service life.
From a manufacturing perspective, 6640 NMN is designed to meet stringent global standards such as IEC, UL, and RoHS. Its stable performance, processing flexibility, and wide adaptability make it suitable for manual, semi-automatic, and fully automated motor manufacturing processes. With the combination of aramid polymer technologies and advanced lamination techniques, 6640 NMN offers a balanced set of mechanical, electrical, and thermal properties that outperform single-layer insulating papers or films.
This article provides a comprehensive overview of 6640 NMN insulation material, including product structure, features, technical parameters, production advantages, application scenarios, usage instructions, handling guidelines, quality control, FAQs, and SEO keywords for English-speaking markets.
6640 NMN belongs to Class F (155°C) or Class H (180°C) insulation depending on the grade of aramid paper and adhesive resin used. Its aramid fiber paper layers provide excellent thermal endurance, resisting thermal aging, shrinkage, and deterioration even after prolonged exposure to high temperatures. This makes the material suitable for heavy-duty industrial motors and transformers requiring high-level thermal stability.
The polyester film at the core significantly enhances dielectric breakdown strength. Combined with the aramid layers, NMN provides high electrical resistance, stable dielectric performance under frequency variations, and consistent insulation even in compact motor designs that demand high voltage endurance.
NMN’s structural composition provides robust mechanical reinforcement. Polyester film contributes tensile strength and resistance to tear propagation, while aramid paper offers additional structural integrity. This ensures the material maintains shape and strength during slot insertion, coil wrapping, or mechanical forming.
6640 NMN is flexible, easily formable, and compatible with various cutting, punching, lamination, and folding processes. It supports manual slot insertion as well as automatic equipment operations, reducing the risk of cracking or delamination.
Aramid fiber paper has an open fiber structure, which enhances compatibility with motor varnishes or insulating resins. This leads to improved adhesion, better thermal transfer, and enhanced long-term insulation stability after varnish impregnation.
NMN insulation resists moisture, oils, solvents, and most industrial chemicals. It also retains stable performance under various environmental conditions such as humidity, temperature fluctuations, and mechanical vibration.
Due to its inherent thermal and mechanical properties, NMN provides long-term reliability in electrical equipment with minimal risk of insulation breakdown, reducing maintenance and replacement needs.
Most 6640 NMN materials meet or exceed UL, IEC, RoHS, and REACH requirements, making them suitable for global markets.
Below are commonly specified technical parameters for NMN materials. Actual values may vary slightly depending on manufacturer specifications, adhesive systems, and layer thicknesses.
Type: N–M–N laminated insulation
Layers:
Outer layers: Aramid paper (Nomex® or equivalent)
Middle layer: Polyester film (PET)
Adhesive: High-temperature resistant resin
Typical thickness options:
0.15 mm
0.18 mm
0.20 mm
0.23 mm
0.25 mm
0.30 mm
0.35 mm
0.40 mm
(Custom thicknesses may also be available.)
Class F (155°C) or
Class H (180°C)
Approx. 1.1 – 1.3 g/cm³ depending on thickness and composition.
Typically ≥ 8 kV, depending on thickness.
Stable under AC and DC environments.
Machine direction: ≥ 70 – 100 N/10 mm
Cross direction: ≥ 40 – 80 N/10 mm
≤2% at 150°C (varies by grade)
Maintains high dielectric strength after heat aging.
Compatible with motor oils, transformer oils, varnishes, epoxy resins, and solvents.
Natural aramid yellow/light beige
Smooth surface with uniform lamination
6640 NMN is widely used in medium and high-grade electrical insulation systems, especially in Class F and Class H applications. Common application fields include:
Slot insulation
Slot wedge liners
Phase insulation
Inter-turn insulation
End-winding insulation
Coil banding and wrapping
EV traction motors
Industrial motors
Compressor motors
Fan motors and pump motors
Layer insulation
Interlayer barriers
Coil wrapping
Core insulation padding
Winding separators
Phase insulation
Armature winding insulation
Slot liners for high-output generators
Relays and contactors
Ballasts
Inductors and coils
Sensors requiring thermal stability
High-speed motors in grinders, drills, and saws
Vacuum cleaners, washing machines, air conditioners, and compressors
Traction motor insulation
Battery pack insulation barriers (high-temperature areas)
Inverter and controller insulation spacers
Welding machines
High-frequency equipment
Industrial automation machinery
The versatility and stability of NMN make it an essential insulation material across multiple industries requiring long-term thermal and electrical reliability.
Suitable for die-cutting, slitting, punching, folding, and laminating.
Avoid excessive stretching to maintain thickness uniformity.
Use sharp cutting tools to prevent edge fraying.
Insert NMN sheets into stator slots manually or via automated slot liner machines.
Ensure smooth placement without creases.
Choose thickness based on motor slot size and required mechanical stability.
NMN tapes can be used to wrap coils, providing added dielectric protection.
Ensure consistent tension to avoid delamination.
NMN is compatible with polyester, epoxy, acrylic, and polyurethane varnishes.
Material absorbs varnish effectively, improving bonding strength and thermal performance.
NMN can endure heat-setting procedures without significant shrinkage.
Always ensure heating temperatures remain within material thermal class limits.
Avoid damage to the surface during installation.
Ensure that NMN is not pierced or torn during mechanical assembly.
Usually supplied in rolls or sheets.
Packed in moisture-resistant wrapping.
Customized width and length available.
Store in clean, dry, well-ventilated spaces.
Ideal temperature: 10–30°C
Humidity: Below 70%
Avoid direct sunlight and dust.
Typically valid for 12–24 months under proper storage conditions.
Handle with clean gloves to prevent contamination.
Avoid folding thick NMN boards to minimize creases.
6640 NMN may comply with:
IEC 60626
IEC 60085
UL Certification
RoHS and REACH environmental standards
Lamination uniformity inspection
Thickness and density testing
Dielectric breakdown strength testing
Tensile strength tests
Heat aging resistance tests
It is used for electrical insulation in motors, transformers, generators, and electronic devices, providing thermal and dielectric protection.
Depending on the grade, it is available as Class F (155°C) or Class H (180°C).
Common standards are 0.15–0.40 mm. Choose based on:
Slot size
Required voltage endurance
Mechanical reinforcement needs
Yes. Its mechanical strength and dielectric stability make it suitable for high-RPM motors.
Yes. The aramid paper layers absorb varnish well, improving bonding and insulation stability.
Yes. Its dielectric strength and heat resistance make it compatible with modern frequency-conversion systems.
Yes. NMN offers a balanced performance combining flexibility, heat resistance, and dielectric properties that single-layer materials cannot achieve.
Most manufacturers offer RoHS and REACH-compliant products.
Keep in a dry, cool, ventilated environment away from sunlight and moisture.
Yes, many suppliers support custom sizes for specific manufacturing needs.
Polyester Film Polyaramid Fiber Paper Composite (6640 NMN) is one of the most important and reliable insulation materials in the electrical manufacturing industry. Its combination of high-temperature resistance, robust dielectric performance, excellent mechanical strength, processing flexibility, and long-term stability makes it ideal for use in motors, transformers, generators, home appliances, automotive systems, and industrial machinery.
As electrical systems continue to demand higher efficiency and thermal performance, NMN insulation remains a core material ensuring safety, reliability, and long service life. Whether applied in high-speed motors, inverter-controlled systems, or heavy-duty industrial machines, 6640 NMN delivers superior insulation protection that meets global standards and industry requirements.
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