Laminasjoner

Laminasjoner refer to the use of thin sheets of ferromagnetic material, typically silicon steel, arranged and insulated to form magnetic cores. The primary purpose is to limit eddy current losses that arise when magnetic fields vary in time, enabling higher efficiency in transformers, motors, and generators.

The sheets are usually made from electrical steel, available in grain-oriented (CRGO) and non-oriented (CRNO) varieties. The steel is often around 0.2 to 0.5 millimeters thick, though thinner or thicker grades exist for specialized applications. Each sheet receives an insulating coating, such as enamel, oxide, or polymer varnish, to prevent electrical contact between sheets after they are stacked. The resulting interlaminar insulation is essential to suppress currents that would otherwise circulate across the core.

Manufacturing and assembly involve stamping or calendaring sheets, applying insonorating coatings, and then stacking the sheets with insulation between them. The stack is clamped or bonded to form a solid core. The arrangement and orientation of the laminations influence magnetic properties, including permeability and losses. Because eddy current losses increase with sheet thickness and frequency, thinner laminations are preferred in high-frequency or high-saturation contexts.

Applications and impact: lamination cores are fundamental in power transformers, electric motors (stator and rotor laminations), and generators. By reducing eddy currents, lamination cores improve efficiency and heat management and allow larger, more reliable machines. Advances include alternative materials such as amorphous or nanocrystalline alloys for specialized high-frequency or low-loss needs, but traditional laminated silicon steel remains dominant in many standard electrical machines.