Magnet wire is copper or aluminum wire coated with a ve […]
Magnet wire is copper or aluminum wire coated with a very thin layer of insulation. It is used in the manufacture of transformers, inductors, motors, generators, speakers, hard disk head actuators, electromagnets, electric guitar pickups and other applications that require tight coil insulation.
The wire itself is usually fully annealed electrorefined copper. Aluminum enameled wire is sometimes used for large transformers and motors. Insulation is usually made from a tough polymer film material, not enamel as the name suggests.
Most of the time, enameled wire consists of fully annealed electro-refined copper to allow for tighter winding when making electromagnetic coils.  High-purity oxygen-free copper grades are used in high temperature applications in reducing atmospheres, or in electric motors or generators cooled by hydrogen.
Aluminum enameled wire is sometimes used as a replacement for larger transformers and electric motors, mainly for economical reasons. Due to its lower conductivity, aluminum wire requires a cross-sectional area 1.6 times larger than copper wire to achieve comparable DC resistance.