High Temperature Multi Color Polyurethane Enameled Silver Plated
Copper Wire
Magnet wire or enameled wire is a copper or aluminum wire coated
with a very thin layer of insulation. It is used in the
construction of transformers, inductors, motors, generators,
speakers, hard disk head actuators, electromagnets, electric guitar
pickups and other applications that require tight coils of
insulated wire.
The wire itself is most often fully annealed, electrolytically
refined copper. Aluminum magnet wire is sometimes used for large
transformers and motors. The insulation is typically made of tough
polymer film materials rather than enamel, as the name might
suggest.
Conductor
The most suitable materials for magnet wire applications are
unalloyed pure metals, particularly copper. When factors such as
chemical, physical, and mechanical property requirements are
considered, copper is considered the first choice conductor for
magnet wire.
Most often, magnet wire is composed of fully annealed,
electrolytically refined copper to allow closer winding when making
electromagnetic coils. High-purity oxygen-free copper grades are
used for high-temperature applications in reducing atmospheres or
in motors or generators cooled by hydrogen gas.
Aluminium magnet wire is sometimes used as an alternative for large
transformers and motors. Because of its lower electrical
conductivity, aluminium wire requires a 1.6-times larger cross
sectional area than a copper wire to achieve comparable DC
resistance.
Insulation
Although described as "enameled", enameled wire is not, in fact,
coated with a layer of enamel paint or vitreous enamel made of
fused glass powder. Modern magnet wire typically uses one to four
layers (in the case of quad-film type wire) of polymer film
insulation, often of two different compositions, to provide a
tough, continuous insulating layer. Magnet wire insulating films
use (in order of increasing temperature range) polyvinyl formal
(Formvar), polyurethane, polyamide, polyester, polyester-polyimide,
polyamide-polyimide (or amide-imide), and polyimide. Polyimide
insulated magnet wire is capable of operation at up to 250 °C. The
insulation of thicker square or rectangular magnet wire is often
augmented by wrapping it with a high-temperature polyimide or
fiberglass tape, and completed windings are often vacuum
impregnated with an insulating varnish to improve insulation
strength and long-term reliability of the winding.
Self-supporting coils are wound with wire coated with at least two
layers, the outermost being a thermoplastic that bonds the turns
together when heated.
Other types of insulation such as fiberglass yarn with varnish,
aramid paper, kraft paper, mica, and polyester film are also widely
used across the world for various applications like transformers
and reactors. In the audio sector, a wire of silver construction,
and various other insulators, such as cotton (sometimes permeated
with some kind of coagulating agent/thickener, such as beeswax) and
polytetrafluoroethylene (Teflon) can be found. Older insulation
materials included cotton, paper, or silk, but these are only
useful for low-temperature applications (up to 105°C).
For ease of manufacturing, some low-temperature-grade magnet wire
has insulation that can be removed by the heat of soldering. This
means that electrical connections at the ends can be made without
stripping off the insulation first.
| Enameled Type | Polyester | Modified Polyester | polyester-imide | Polyamide-imide | polyester-imide /Polyamide-imide |
| Insulation Type | PEW/130 | PEW(G)/155 | EIW/180 | EI/AIW/200 | EIW(EI/AIW)220 |
| Thermal class | 130, CLASS B | 155, CLASS F | 180, CLASS H | 200, CLASS C | 220, CLASS N |
| Standard | IEC60317-0-2 IEC60317-29 MW36-A | IEC60317-0-2 IEC60317-29MW36-A | IEC60317-0-2 IEC60317-29 MW36-A | IEC60317-0-2 IEC60317-29 MW36-A | IEC60317-0-2 IEC60317-29 MW36-A |
