Flexible Insulation NHN
NHN is a three-layer flexible laminate: Nomex® aramid paper on both faces with a polyimide film core, bonded with a Class H adhesive by hot rolling. It is the standard slot, phase and turn-to-turn insulation for Class H (180 °C) motors and the interlayer insulation in Class H dry-type transformers. The reason NHN reaches Class H, while the cheaper NMN does not, is the core: polyimide film. Polyimide carries the dielectric and thermal performance of the composite; the Nomex faces give it mechanical toughness, edge tear resistance and resin absorbency. Change the core to polyester and you have NMN — Class F (155 °C) — at a lower price. Core polyimide film: 25 – 190 µm thickness (the 0.03 – 0.125 mm film range in common use) Finished laminate: 0.13 – 0.30 mm, six standard constructions Thermal class: H (180 °C) Roll width: 100 – 500 mm standard · slit to any width to suit your slot Roll length: 200 m / core 76 mm or 152 mm
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Product Introduction
What NHN Actually Is
NHN is not a polyimide tape and contains no adhesive. It is a laminated sheet of three layers:
Nomex® aramid paper ← outer face
Polyimide film ← core (this is what makes it Class H)
Nomex® aramid paper ← outer face
Reading the grade notation. The constructions are written as three figures, in mils (1 mil = 25 µm), for example 2-4-2:
| 2 | – | 4 | – | 2 |
|---|---|---|---|---|
| Nomex face, 2 mil (50 µm) | Polyimide core, 4 mil (100 µm) | Nomex face, 2 mil (50 µm) |
So the six standard constructions range from 2-1-2 (0.13 mm total, 25 µm polyimide core) up to 2-7.5-2 (0.30 mm total, 190 µm polyimide core). In every case the total is thicker than the core, because the two Nomex faces add roughly 0.05 mm each side.
Our designation: 6650 is the NHN grade. Related laminates in the same family: 6640 (NMN), 6630 / 6641 / 6643 (DMD types), plus NH, NM and DM constructions.
Why NHN Reaches Class H: The Polyimide Core
This is the decision that determines what you buy, so it is worth being precise.
| Layer | What it contributes | What happens without it |
|---|---|---|
| Polyimide core | Thermal endurance and dielectric strength - the reason NHN can be rated Class H | Replace with polyester and the laminate drops to NMN, Class F (155 °C) |
| Nomex faces | Mechanical toughness, tear resistance at cut edges, resin absorbency for impregnation and varnish bonding | Bare polyimide film is thin and easily damaged at the slot edge |
| Class H adhesive | Bonds the layers and must itself survive 180 °C | A lower-class adhesive caps the whole laminate regardless of the core |
Practical consequence: the polyimide core is the expensive part of NHN. If your motor is Class H, the core is not optional - a polyester-cored laminate will not hold its dielectric strength at 180 °C, and the failure will appear as an insulation fault after thermal ageing, not at first assembly. If your motor is Class F or lower, NMN does the same job for less money and specifying NHN simply adds cost.
NHN vs NMN vs NKN vs DMD - Choose by Insulation Class
| Laminate | Construction | Core film | Thermal class | Relative cost | Choose it when |
|---|---|---|---|---|---|
| NHN (6650) | Nomex / Polyimide / Nomex | Polyimide | H (180 °C) | Highest | Class H motors; Class H dry-type transformers; high temperature plus high dielectric demand |
| NKN | Nomex / Kapton® / Nomex | Polyimide | H (180 °C) | Highest | Equivalent to NHN - Kapton is a polyimide brand name |
| NMN (6640) | Nomex / Polyester / Nomex | Polyester (PET) | F (155 °C) | Lower | Class F motors - the economical choice where 180 °C is not required |
| DMD (6630 / 6641 / 6643) | Polyester mat / PET / polyester mat | Polyester | B / F | Lowest | Lower-temperature appliances, cost-driven designs |
| NH | Nomex / Polyimide | Polyimide | H (180 °C) | - |
Technical Data
NHN / 6650 flexible laminate - standard constructions
| Construction (mil) | Nominal thickness (mm) | Thickness tolerance (± %) | Nominal grammage (g/m²) | Polyimide core (µm) | Tensile MD (N/10 mm) | Tensile TD (N/10 mm) | BDV, unbent (kV) |
|---|---|---|---|---|---|---|---|
| 2-1-2 | 0.13 | 15 | 135 ± 16 | 25 | 140 | 80 | 7 |
| 2-2-2 | 0.17 | 15 | 170 ± 20 | 50 | 160 | 90 | 9 |
| 2-3-2 | 0.19 | 15 | 200 ± 24 | 75 | 330 | 280 | 12 |
| 2-4-2 | 0.22 | 15 | 230 ± 27 | 100 | 360 | 300 | 13 |
| 2-5-2 | 0.23 | 15 | 270 ± 32 | 125 | 390 | 320 | 14 |
| 2-7.5-2 | 0.30 | 15 | 360 ± 43 | 190 | 400 | 340 | 19 |
Slit to Your Slot Width
NHN is supplied in jumbo or standard rolls and then slit to the width your stator slot actually needs - so you are not paying for insulation you trim off and throw away.
| Parameter | Options |
|---|---|
| Standard roll width | 100 – 500 mm |
| Slitting | To any width within the roll width - tell us your slot width |
| Slit tolerance | [state your achievable tolerance] |
| Roll length | 200 m standard; other lengths on request |
| Core | 76 mm or 152 mm, paper or plastic |
| Also available | Die-cut pieces / pre-cut strips to length |
Why slit width matters commercially: a motor manufacturer running three frame sizes needs three insulation widths. Buying one standard width and slitting in-house generates offcut that cannot be reused, plus an extra operation and a slitting burr to control. Ordering pre-slit to each slot width removes that waste.
Tell us for each size: slot width, slot height, the required strip length, the cut edge quality you need (a clean, non-fraying edge is the whole reason for the Nomex faces), and the annual volume per width.
Where NHN Is Used
| Application | Why NHN |
|---|---|
| Slot insulation in Class H motors | The primary use - the laminate lines the stator slot and must hold dielectric strength at 180 °C |
| Interphase insulation between phases | Withstands the voltage stress between phase windings |
| Turn-to-turn / interturn insulation | Thin enough to fit within the winding while holding class |
| Liner insulation | Provides a continuous insulation barrier in the slot |
| Interlayer insulation in Class H dry-type transformers | Layer-to-layer dielectric separation at Class H temperature |
| Class B or F motors in special locations | NHN is sometimes specified where a Class F machine has a local hot spot requiring Class H material |
Packing and Roll Formats
| Item | Specification |
|---|---|
| Roll packing | One roll per carton, PP inner wrap |
| Core | Paper or plastic, 76 mm / 152 mm; roll on 76 mm plastic core as standard |
| Roll width | 100 – 500 mm |
| Roll length | 200 m |
| Outer packing | 27 kg calcium-plastic carton |
How to Specify Your Laminate
Send these and we can quote accurately:
| # | Line | Example |
|---|---|---|
| 1 | Construction | 2-4-2 (name the mil notation, or the total thickness) |
| 2 | Total thickness and tolerance | 0.22 mm, ± 15 % |
| 3 | Slit width | 42 mm, one width per slot size (list each) |
| 4 | Roll length and core | 200 m, 76 mm plastic core |
| 5 | Insulation class required | Class H (180 °C) |
| 6 | Application | Slot insulation / interphase / turn-to-turn / liner / transformer interlayer |
| 7 | Quantity per size | Annual and first-order volume, normally by weight |
| 8 | Any special requirement | Dielectric strength minimum, grammage, adhesive specification, edge quality |
FAQ
What does NHN stand for?
It is a three-layer flexible laminate: Nomex aramid paper on both faces with a polyimide film core - Nomex / polyimide / Nomex. Our grade designation is 6650.
Does NHN contain adhesive?
No adhesive in the sense of a self-adhesive tape. The three layers are bonded with a Class H laminating adhesive. If what you need is a polyimide tape with silicone adhesive, see our insulation polyimide film tape instead.
What is the difference between NHN and NMN?
The core. NHN has a polyimide core, giving Class H (180 °C). NMN has a polyester (PET) core, giving Class F (155 °C) at a lower price. Everything else about the construction is similar.
What is the difference between NHN and NKN?
Essentially the same product - Kapton® is a polyimide brand name. Both have a polyimide core and are Class H.
What thicknesses do you supply?
Six standard constructions from 2-1-2 (0.13 mm, 25 µm polyimide core) to 2-7.5-2 (0.30 mm, 190 µm core). Tell us the dielectric strength you need and the space available in the slot and we will recommend a construction.
Can you supply the polyimide film on its own?
Yes - polyimide film in the 0.03 – 0.125 mm range is available unslitted or slit to width, for applications that need the film without the Nomex faces. See our insulating polyimide film page.
Can you slit to my slot width?
Yes. Standard roll width is 100 – 500 mm and we slit to the width your slot requires, so you do not pay for material you trim off. Give us each slot width and the annual volume.
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