Material thickness describes the dimension between the two opposing surfaces of a material. It is a central parameter in materials engineering, as it significantly influences electrical, mechanical and thermal properties.
Put simply: material thickness determines how stable, how flexible and how insulating a material is. Particularly in the electrical and automotive industries, it determines whether a component functions reliably or fails.
Material thickness in electrical insulation
For insulating materials, thickness has a direct influence on electrical dielectric strength, flexibility and mechanical load-bearing capacity.
- Thinner materials (e.g. 0.05 to 0.125 mm polyimide films): high flexibility, tight bend radii possible, frequently used in winding heads, intermediate layers or masking.
- Medium thicknesses (e.g. 0.18 to 0.35 mm laminate composites such as NMN or DMD): stable slot insulation, layer insulation.
- Thicker materials (e.g. 0.5 to 1 mm pressboard, mica plates): high mechanical stability, used in transformers or as covers.
Thickness therefore determines whether an insulating material is flexible, dimensionally stable or highly robust.
Measurement technology and tolerances
The measurement of material thickness is performed depending on the type of material with:
- Micrometer screws (mechanical thickness measurement, +/- 1 to 2 micrometers).
- Tactile and optical systems for thin films.
- Laser or ultrasonic methods for larger thicknesses and for inline monitoring.
Tolerances are specified in DIN ISO 2768 and in specific material standards:
- For films (e.g. polyester, polyimide): +/- 10 to 15 % depending on the manufacturing process.
- For laminates (e.g. DMD, NMN): +/- 0.02 to 0.05 mm, depending on layer structure.
- For pressboard: graded tolerances depending on thickness and delivery form.
These tolerances are decisive, as deviations can lead to problems with assembly, slot fit and electrical insulation.
Material thickness and electrical properties
- Dielectric strength: as a rule rises proportionally with thickness, but not indefinitely (limited by partial discharge).
- Creepage distances: insulation distances improve with greater thickness.
- Thermal conduction: thicker materials act more strongly as thermal insulators but can impede heat dissipation.
- Capacitive properties: in capacitors and insulation systems, thickness plays a central role in field distribution.
Applications and practical examples
- Electric motors: slot insulation from NMN in thicknesses between 0.18 and 0.35 mm.
- Generators: layer and field coil insulation with mica and aramid laminates from 0.2 mm.
- Transformers: pressboard and laminates between 0.5 and 1 mm as coil and cover insulation.
- Conductor track covering (FPCB): polyimide films in thicknesses from 25 micrometers.
- Automotive: adhesive tapes and Kapton films in thin gauges for high-voltage on-board networks.
Advantages and challenges
Advantages
- Targeted adjustment of mechanical and electrical properties.
- Broad range available: from ultra-thin films to stable plates.
- Precise manufacturing technologies allow tight tolerances.
Challenges
- Too low thickness: risk of mechanical damage and breakdown.
- Too high thickness: poorer heat dissipation, space problems in slots.
- Varying thicknesses: assembly problems, inhomogeneities in electrical fields.
GOBA Takeaway
Material thickness is much more than a geometric dimension: it determines the functionality of insulating materials in electrical machines. Correct selection and observance of tolerances is essential for operational safety, efficiency and service life. For buyers, designers and technicians the rule applies: material thickness must be precisely matched to the application and checked according to the relevant standards.