Polyimide Film Laminated with Nomex Paper Insulation Material for Motors and Transformers

1. What Is Polyimide Film and Nomex Paper Laminate?

1.1 Structure of the Composite Insulation Material

Our TF6051-DK is a high-performance composite insulation material constructed by laminating one layer of Nomex paper with one layer of polyimide film. This two-layer laminate combines the dielectric strength and thermal stability of polyimide film with the mechanical toughness and flexibility of Nomex paper. This product is supplied in standard rolls (0.08 mm thick, 1000 mm wide, 1500 m long) and is designed specifically for high-volume, automated insertion into motor slots and transformer windings.

1.2 Why Polyimide Film and Aramid Paper Are Combined

The combination of polyimide film and Nomex paper leverages their complementary properties. Polyimide has high dielectric strength, low loss and excellent heat resistance, but it is hard and expensive; Nomex, on the other hand, gives the material mechanical toughness and flexibility at a lower cost—the combination of the two achieves comprehensive performance superior to that of a single material. Nomex paper provides excellent mechanical strength, superior flexibility, and good thermal resistance at a more economical cost. In this laminate, the polyimide layer serves as the high-voltage dielectric barrier, while the Nomex paper delivers tear resistance, surface adhesion, and structural support. In harsh electrical environments, this combination outperforms insulation layers made of single materials. In addition, the laminated material has good shape retention, making it easy to install into motor slots and transformer windings.

2. Key Features of TF6051-DK Insulation Material

• High Temperature Resistance (Class H, ≥180°C): Rated with a long-term heat-resistance temperature index of ≥180°C, suitable for continuous operation in elevated thermal environments. The use of high temperature polyimide film ensures low heat contraction rates of ≤1.0% at 150°C and ≤3.0% at 400°C, maintaining dimensional stability during thermal cycling and varnish curing.
• Excellent Electrical Insulation Performance: Achieves electrical strength of ≥150 MV/m at operating frequency, providing a robust barrier against electrical breakdown. Maintains high resistivity at 200°C (surface ≥1.0×10¹³ Ω, volume ≥1.0×10¹⁰ Ω.m), effectively minimizing leakage currents even in contaminated, high-heat conditions.
• Good Mechanical Strength and Flexibility: Delivers tensile strength of ≥135 MPa (MD) and ≥115 MPa (TD), along with ≥35% elongation. This combination ensures excellent tear resistance and the ability to conform around curved surfaces and narrow slots without cracking.
• Low Dielectric Loss and High Stability: Features a low dielectric loss factor of ≤4.0×10⁻³ at 48–62 Hz, which reduces energy dissipation and heat generation in AC fields. Offers strong resistance to moisture and chemicals, along with excellent compatibility with impregnating varnishes for void-free insulation systems.

3. Technical Specifications of TF6051-DK

4. Key Advantages in Electrical Applications

• Improved Slot Fill Rate in Motors: With a slim 0.08 mm thickness, this laminate consumes minimal space within stator slots, allowing a higher copper fill rate. This directly translates to reduced copper losses and improved torque density without increasing the motor’s physical size.
• Reduced Insulation Thickness: The high dielectric strength enables engineers to specify thinner insulation layers compared to conventional materials like plain Nomex or polyester, facilitating more compact and lightweight designs for space-constrained applications such as automotive traction motors and aerospace actuators.
• Better Compatibility with Varnish: The material’s surface properties ensure excellent wetting and adhesion with standard insulating varnishes. This eliminates air voids during impregnation, preventing partial discharge and significantly enhancing long-term system reliability.
• Long-Term Thermal Stability: Engineered for longevity, the ≥180°C temperature index guarantees that the material retains its dielectric and mechanical integrity over extended service life, reducing the risk of premature aging and lowering overall lifecycle maintenance costs.

5. Main Applications in the Electrical Industry

5.1 H-Class Motors

TF6051-DK is designed for Class H motors, rated for continuous operation at temperatures up to 180°C. These motors are widely used in high-ambient-temperature environments—steel mills, foundries, glass plants, and cement kilns, for example. With its thermal endurance, dielectric strength, and mechanical flexibility, this material is well-suited for slot, phase, and inter-wire insulation in demanding motor applications. With TF6051-DK, motor manufacturers can meet H-class temperature requirements while keeping designs compact and reliability high.

5.2 Generators

Generator insulation systems are subject to high temperatures, mechanical vibration, centrifugal forces, and thermal expansion. TF6051-DK’s high tensile strength, elongation, and dimensional stability make it well-suited for generator stator and rotor insulation. Its low dielectric loss characteristic is particularly important for large generators operating at high voltage, because in such equipment, energy dissipation within the insulation layer can lead to efficiency loss and localized heating. Additionally, good varnish compatibility ensures complete encapsulation and protection of generator windings in harsh environments.

5.3 Dry-Type Transformers

Dry-type transformers rely on solid insulation systems rather than liquid coolants, placing stringent demands on insulation materials. TF6051-DK’s high-temperature endurance, low dielectric loss, and excellent electrical strength make it a reliable choice for layer insulation, phase insulation, and lead insulation in dry-type transformers. Low heat contraction and stable properties under thermal cycling keep the insulation system tight and effective over time—enhancing the safety and performance of dry-type transformers in commercial, data center, renewable energy, and industrial applications.

5.4 Slot Insulation, Phase Insulation, and Inter-Wire Insulation

TF6051-DK serves multiple insulation functions in one device—slot, phase, and inter-wire insulation. It is placed inside the stator/rotor slots to isolate the windings from the grounded core, separate the phase windings to prevent faults, and isolate the conductors to avoid turn-to-turn short circuits. At 0.08 mm thick and highly flexible, it folds and inserts easily; the yellow color simplifies visual inspection.

6. Customization and Ordering Information

As a professional polyimide film manufacturer, we offer standard specification of 0.08 mm × 1000 mm × 1500 m, with custom widths and lengths available based on specific production requirements. To place an order or request a sample, customers should contact us with their specific dimensions, quantity requirements, and any additional technical considerations.

7. Conclusion

TF6051-DK is a polyimide/Nomex laminate for demanding electrical applications. It combines the heat/dielectric strength of polyimide with the mechanical toughness of Nomex—ideal for Class H motors, generators, and dry-type transformers. Standard sizes, custom options, proven performance—a solid choice for the global electrical industry. If you are interested in our products, please feel free to contact us for a quote.