NMN Insulation Paper Class H Grade 6640
NMN (Nomex-Mylar-Nomex) 6640 — premium three-layer flexible composite laminate. Polyester film (Mylar / PET) core bonded between two Nomex aramid paper outer layers using H-grade resin. Delivers continuous 180°C thermal endurance, high dielectric strength, inherent flame resistance, and mechanical toughness for slot liner, phase insulation, and transformer interlayer applications.
ACC Insulations supplies NMN insulation materials to OEMs in dry-type transformer manufacturing, motor winding, EV traction systems, and high-performance Class H electrical equipment across India.
What Is NMN Insulation Paper?
NMN 6640 — three-layer flexible composite insulation. Middle layer: polyester film (Mylar / PET) for high dielectric barrier performance. Outer layers: Nomex aramid paper on both faces for thermal endurance and mechanical toughness. All three bonded with H-grade (180°C) synthetic resin.
Nomex outer layers add inherent flame resistance, chemical stability, and compatibility with varnish and transformer oil impregnation systems. NMN replaces DMD wherever Class H thermal rating, higher flame safety, or superior tear resistance matters — particularly in dry-type transformers, EV traction motors, and aerospace-grade coils.
Also referred to as: Nomex-Mylar-Nomex paper, NMN 6640 flexible laminate, aramid-PET composite insulation, Class H slot liner material.
NMN 6640 — Layer Construction
Total laminate thickness: 0.13 mm to 0.50 mm · Roll width: 3.5 mm to 914 mm (custom on request) · Colour: Golden Yellow / Orange
Key Properties & Features
- Class H (180°C) thermal endurance — withstands prolonged thermal cycling without degradation; H-grade resin bonding maintains structural integrity.
- High dielectric strength — PET polyester film core blocks voltage breakdown; prevents current leakage and short circuits in high-voltage winding systems.
- Inherent flame resistance — Nomex aramid outer layers self-extinguish; no secondary flame retardant treatment needed.
- Superior mechanical toughness — high tensile strength, tear resistance, and puncture resistance; survives automated high-speed slot insertion without damage.
- Excellent abrasion resistance — protects enamelled wire insulation during automated winding; reduces insulation failure risk.
- VPI / oil / varnish compatibility — Nomex surfaces bond well with polyester and epoxy VPI resin systems; chemically stable in transformer oil.
- Very low moisture absorption — below 2% moisture content ready-to-use; no vacuum drying required unlike cellulose-based materials.
- Good flexibility and conformability — bends and forms cleanly into motor slot profiles; compatible with automated winding line processes.
- Long service life — Nomex aramid fibres resists thermal ageing, chemical attack, and radiation degradation over decades.
Technical Specifications — NMN 6640
| Grade / Standard | 6640 (UL recognized up to 180°C) |
|---|---|
| Structure | 3-ply: Nomex® paper / Polyester film (Mylar® PET) / Nomex® paper |
| Bonding Adhesive | H-grade (180°C rated) acid-free synthetic resin |
| Thermal Class | Class H — 180°C continuous operation |
| Thickness Range | 0.13 mm to 0.50 mm (custom available) |
| Roll Width | 3.5 mm to 914 mm (custom slit widths on request) |
| Dielectric Strength | High — Mylar/PET film core barrier |
| Flame Resistance | Inherent — Nomex aramid (UL 94 V-0 comparable) |
| Moisture Absorption | Very low (<2% ready-to-use) |
| Colour | Golden Yellow / Orange |
| Form Available | Rolls, sheets, custom slit tapes |
| Impregnation | Varnish, polyester/epoxy VPI resin, transformer oil |
| Storage | Dry, ventilated room — 20°C, 50% RH (12-month shelf life) |
NMN vs DMD — Which to Choose?
Both NMN and DMD share an identical Mylar/PET dielectric core. Critical difference: outer face material determines thermal class and flame performance. Choose NMN wherever operating temperature exceeds 155°C or flame safety requirements apply.
| Property | NMN (Nomex-Mylar-Nomex) | DMD (Dacron-Mylar-Dacron) |
|---|---|---|
| Outer Layer Material | Nomex® aramid paper | Dacron polyester nonwoven |
| Thermal Class | Class H — 180°C | Class F — 155°C |
| Flame Resistance | Inherent (Nomex) | Standard |
| Dielectric Core | Mylar / PET film | Mylar / PET film |
| Mechanical Strength | Higher tear & puncture resistance | Good |
| Oil / Varnish Resistance | Excellent (Nomex) | Good |
| Typical Colour | Golden Yellow / Orange | White |
| Grade Reference | 6640 | 6630 |
| Best For | Dry-type transformers, traction motors, EV drives, aerospace coils | Standard motors, oil-type transformers, general coils |
Also compare: DMD Insulation Paper · NHN (Nomex-Polyimide-Nomex) for Class C (>220°C) applications.
Applications of NMN 6640 Insulation Paper
NMN 6640 serves as slot liner, slot closure, phase insulation, and interlayer insulation across these equipment categories:
Specific winding uses: slot liner insulation, slot closure insulation, phase-to-phase insulation, interlayer insulation, turn-to-turn insulation, wedge insulation, and ground wall insulation in Class H equipment.
NMN Insulation Variants Available
- Standard NMN 6640 — Class H, 180°C. Thickness 0.13 mm to 0.50 mm. Most common motor and transformer grade.
- NMN with enhanced PET core — thicker polyester film for higher dielectric rating; used in elevated-voltage winding systems.
- Prepreg NMN — pre-impregnated with resin for fast winding cycles and VPI-free production lines.
- Roll form — standard and custom slit widths from 3.5 mm up to 914 mm.
- Sheet form — custom cut-to-size for punching, die-cutting, and CNC slot liner production.
How NMN Insulation Paper Gets Made
Understanding manufacturing process validates quality expectations:
Why Source NMN Insulation from ACC Insulations?
Uniform Nomex-to-Mylar bond across every roll. No delamination, no air pockets.
Any thickness, roll width, or sheet size. OEM and high-volume requirements handled.
Rigorous QC with electrical strength verified before every dispatch.
Timely delivery for high-volume transformer and motor manufacturers across India.
Certified Class H thermal rating. No grade substitution. Competitive pricing.
Expert help on material selection, thickness specification, and application advice.
Engineering Tools Suite
Unsure whether NMN (Class H) or DMD (Class F) fits your application? Smart insulation selector and thermal class calculator — pick the right material fast.
Frequently Asked Questions — NMN Insulation Paper
NMN = Nomex-Mylar-Nomex. Three-layer flexible laminate: polyester film (Mylar/PET) core sandwiched between two Nomex aramid paper outer layers. Grade 6640. Class H rated at 180°C. Delivers inherent flame resistance, high dielectric strength, and superior mechanical toughness compared to standard DMD laminates.
Class H — continuous operating temperature up to 180°C. H-grade resin bonding ensures laminate stability under prolonged thermal cycling. Preferred over Class F DMD for high-temperature motors, dry-type transformers, traction systems, and EV drive motors where thermal margins matter.
Identical PET dielectric core in both. Outer face material differs: DMD uses Dacron polyester nonwoven — Class F (155°C). NMN uses Nomex aramid paper — Class H (180°C) with inherent flame resistance. NMN also offers better tear strength and oil resistance. Choose NMN whenever the operating temperature exceeds 155°C or flame safety standards apply.
Yes. Nomex aramid outer layers resist transformer oil, varnish, and epoxy resin (VPI) impregnation systems. Long-term dielectric stability confirmed in oil-immersed environments. Suitable for both dry-type and oil-filled power transformer applications.
Slot liner insulation (between stator/rotor core and enamelled conductors), slot closure insulation, phase-to-phase insulation, interlayer insulation, and wedge insulation. Abrasion resistance protects wires during automated high-speed winding. Flexibility allows clean bending into tight slot profiles.
Standard thickness: 0.13 mm to 0.50 mm. Custom roll widths from 3.5 mm to 914 mm. Sheet form available in custom cut sizes. OEM volumes and special dimension requests welcome — contact our technical team for specifications.
