DMD Insulation Paper — Dacron-Mylar-Dacron Polyester Film Composite
DMD insulation paper (Dacron-Mylar-Dacron) — a three-layer flexible composite laminate for electrical insulation in motors, transformers, and coils. Polyester film (Mylar/PET) forms the dielectric core. Nonwoven polyester fabric (Dacron) bonds to both surfaces for mechanical reinforcement.
ACC Insulations supplies Class B and Class F DMD in roll and sheet form. Custom thickness, slit width, and OEM-specific packaging available.
What DMD Insulation Paper Is
DMD stands for Dacron-Mylar-Dacron — a three-layer structure. Layer 1: nonwoven polyester fabric (Dacron). Layer 2: biaxially oriented polyester film (PET/Mylar) — dielectric core. Layer 3: nonwoven polyester fabric (Dacron). F-class or B-class adhesive bonds all three layers.
Polyester film provides high dielectric strength and blocks electrical breakdown. Dacron layers add tear resistance, mechanical toughness, and varnish impregnation compatibility. Together: balanced electrical, mechanical, and thermal performance at low cost.
Standard designations: 6630-B (Class B, 130°C) and 6641-F (Class F, 155°C). Both comply with JB/T 4060-1991. Available white in color. Width: 980–990mm standard. Custom slit widths on request.
Key Performance Properties
- High dielectric strength — resists electrical breakdown in LV/MV equipment
- Class B & Class F thermal rating — 130°C and 155°C operating range
- Excellent mechanical toughness — high tear and puncture resistance
- Varnish impregnation compatible — bonds with epoxy, polyester & acrylic varnishes
- Low moisture absorption — stable dielectric performance in humidity
- Chemical resistance — stable in transformer oil, mild acids, solvents
- Slot geometry adaptability — flexible for manual and automated insertion
- Cost-efficient — lower cost than aramid NMN/NHN for standard applications
Technical Specifications
| Property | Class B (6630-B) | Class F (6641-F) |
|---|---|---|
| Core Layer | PET Polyester Film (Mylar) | |
| Outer Layers | Nonwoven Polyester Fabric (Dacron) | |
| Max Operating Temp | 130°C | 155°C |
| Dielectric Strength | High (varies by thickness) | |
| Standard | JB/T 4060-1991 | |
| Color | White | |
| Roll Width (standard) | 980 – 990mm | |
| Chemical Resistance | Oil, mild acids, solvents | |
Available Thickness Range
| Nominal Thickness (mm) | Tolerance | Typical Use |
|---|---|---|
| 0.13 | ±0.015mm | Turn-to-turn insulation, tight slots |
| 0.15 | ±0.015mm | Motor slot liner (small motors) |
| 0.20 | ±0.020mm | Phase insulation, interlayer |
| 0.25 | ±0.020mm | Transformer layer insulation |
| 0.30 | ±0.025mm | Slot closure, gasket insulation |
| 0.35 | ±0.025mm | Heavy duty motor slot liners |
| 0.40 | ±0.030mm | Generator insulation, large coils |
| 0.50 | ±0.035mm | End-wrap, barrier insulation |
Custom slit widths and intermediate thicknesses available on request for OEM production lines.
Applications of DMD Insulation Paper
Types of DMD Insulation Available
- Class B DMD (6630-B) — 130°C, standard Y-series motors, general electrical equipment
- Class F DMD (6641-F) — 155°C, dry-type transformers, high-load motors, inverter-duty applications
- Prepreg DMD (F-DMD-P) — epoxy-resin impregnated, cures at moderate temp, bonds to copper/aluminum foil
- Roll Form — standard width 980–990mm, custom slit rolls for automated winding
- Sheet Form — cut-to-size sheets for slot liners, gaskets, and prototyping
DMD vs NMN vs NHN — Which to Choose?
DMD
- Class B / Class F
- Up to 155°C
- Polyester film core
- Cost-efficient
- LV/MV motors & transformers
NMN (Nomex)
- Class H
- Up to 180°C
- Nomex aramid fabric
- Higher cost
- High-temperature motors
NHN
- Class H+
- Up to 200°C
- Polyimide + Nomex
- Premium cost
- Aerospace, traction motors
Choose DMD for standard industrial motors and transformers below 155°C. Upgrade to NMN or NHN only when thermal demands exceed DMD's Class F limit.
Why Choose ACC Insulations for DMD?
- Direct Indian component manufacturer — no middlemen, competitive pricing
- Consistent lamination quality with strict in-process QC
- Custom thickness, slit width & roll length for OEM lines
- Class B and Class F stock maintained for fast dispatch
- Technical application support for motor winding & transformer teams
- Pan-India supply — transformer hubs, motor OEMs, switchgear manufacturers
Insulation Engineering Tools
Determine Class B vs Class F thermal endurance for your DMD application. Slot sizing calculators, thermal class selectors, and voltage withstand guides.
Frequently Asked Questions
DMD — Dacron-Mylar-Dacron. Three layers: two outer layers of nonwoven polyester fabric (Dacron) bonded to a central polyester film (Mylar/PET) using heat-resistant adhesive. Standard designations: 6630-B (Class B) and 6641-F (Class F).
Class B DMD (6630-B): max 130°C continuous operating temperature. Class F DMD (6641-F): max 155°C. Choose Class F for dry-type transformers, high-load motors, variable-frequency drives, and inverter-duty equipment. Class B for standard Y-series motors and general electrical appliances.
Primary uses: motor slot liner insulation, phase-to-phase insulation, transformer interlayer insulation, turn-to-turn insulation, coil wrapping, generator insulation, and slot closure in low and medium voltage electrical equipment.
ACC Insulations stocks: 0.13mm, 0.15mm, 0.20mm, 0.25mm, 0.30mm, 0.35mm, 0.40mm, and 0.50mm. Custom intermediate thicknesses and slit widths available for OEM production requirements.
DMD: polyester film + polyester fabric — Class B/F (up to 155°C) — cost-effective for standard applications. NMN: polyester film + Nomex aramid fabric — Class H (up to 180°C) — higher cost, needed only when application temperatures exceed 155°C. NHN: polyimide + Nomex — Class H+ up to 200°C — premium tier for aerospace and traction motors.
Yes. DMD withstands transformer oil, chemical solvents, and mild acids — stable performance long-term. Suitable for oil-immersed transformer layer insulation, interlayer insulation, and dry-type transformer coil barrier insulation.
Yes. DMD absorbs epoxy resin, polyester varnish, and acrylic impregnating varnishes readily. Compatible with dip-and-bake, trickle impregnation, and vacuum pressure impregnation (VPI) processes used in motor and transformer manufacturing.
