Laminate composites are multilayer materials created by joining different layers. The goal is to combine the advantages of the individual materials: high electrical insulation, mechanical strength and thermal resistance.
In simple terms: laminate composites are “material sandwiches” precisely tailored to the requirements of electric motors, generators and transformers. They form the basis of many insulating parts that are installed as cuts, stamped parts or formed parts in electrical machines.
Structure and functional principle
A laminate composite consists of at least two layers bonded together by gluing, impregnating, pressing or laminating. Typical components:
- Films: polyester (HOSTAPHAN, Mylar), polyimide (Kapton).
- Papers: aramid paper (Nomex), pressboard.
- Nonwovens: polyester or glass fleece for mechanical reinforcement.
- Resin and adhesive systems: acrylate, epoxy or polyester layers as binders.
The properties result from the layer combination: insulating strength, temperature class, dielectric strength, flexibility or mechanical stability.
Typical laminate types
- DMD (polyester fleece, polyester film, polyester fleece): combination of electrical strength and mechanical stability, insulation class B or F.
- NMN (Nomex, polyester film, Nomex): high thermal resistance up to class H, widely used in motors and generators.
- DMD variants with high-temperature films: for applications in class H.
- Mica laminates: mica tapes and mica composite sheets for high voltage and high thermal stress.
- Aramid/PET combinations: for flexible, thermally robust insulating parts.
- NPiN/NKN: (Nomex, polyimide film, Nomex), (Nomex, Kapton, Nomex).
Manufacturing and converting
Laminate composites are produced as rolls or sheets and further processed by converters. Common processes:
- Roll slitting: cuts for slots and interlayers.
- Die cutting: precise insulating parts per DIN ISO 2768.
- Kiss-cut: self-adhesive laminate insulating parts for easy removal.
- Laser cutting: for prototypes or complex geometries.
- Laminating: combination with adhesives or additional protective layers.
Properties and requirements
- Electrical: high dielectric strength, good tracking resistance, defined surface resistance.
- Thermal: insulation classes B (130 Grad C), F (155 Grad C), H (180 Grad C) up to higher classes with Kapton and mica.
- Mechanical: abrasion resistance, dimensional stability, bending behaviour.
- Chemical: resistance to varnishes, resins, oils and solvents.
- Processing: suitable for automatic winding processes, VPI impregnation and resin systems.
Applications of laminate composites
- Electric motors: slot insulation, slot closures, interlayers.
- Generators: groundwall insulation, spacer layers.
- Transformers: coil insulation, layer interlayers.
- Automotive (e-mobility): hairpin windings, high-voltage motors, intermediate insulation.
- General electrical engineering: stamped parts, formed parts and covers for dielectric strength and thermal stability.
Advantages and challenges
Advantages
- Combine the best properties of multiple materials.
- Tailored solutions for voltage and temperature requirements.
- Versatile processing options (stamping, cutting, laminating).
- Economical production in large volumes.
Challenges
- Complexity of material selection.
- Careful quality control needed to prevent delamination.
- Different thermal expansion coefficients can create internal stresses.
- Material and process costs for high-performance composites.
GOBA Takeaway
Laminate composites are the backbone of modern insulation systems. They combine the advantages of films, papers, fleeces and resins into a tailored insulating material. In electric motors, generators and transformers they ensure electrical safety, thermal stability and mechanical resilience. For designers and buyers the rule is: the right laminate combination substantially determines the service life and efficiency of electrical machines.