Rea Magnet Wire

Coordinates: 41°3′40″N 85°5′30.8″W / 41.06111°N 85.091889°W / 41.06111; -85.091889

Rea Magnet Wire Company, Inc. is one of the world's largest manufacturers of magnet and nonferrous wire products. Rea produces copper, aluminum and brass-insulated magnet wire and bare wire used in the manufacture of motors, transformers and coils. Rea also manufactures a number of specialty wire products.

Magnet wire industry

Until George Jacobs invented a practical enamel for the purpose, cloth was used to insulate magnet wire. This had a number of drawbacks such as, the cloth being too expensive, becoming worn, and bulky. Wire with enamel insulation could be more densely packed, allowing smaller, more efficient motors, coils and other electromagnetic devices.

Jacobs had worked as a chemist in GE's Fort Wayne, Indiana plant. In fact, he met and married his wife Ethel when he worked there. He got a better job as a chemist with Sherwin-Williams in Cleveland, Ohio but continued to work privately on an enamel wire insulation. He tried to exploit his invention there, but lack of capital and management skills hampered him. His father-in-law, successful Fort Wayne hardware wholesaler W.E. Mossman, was a lonely widower. He agreed to back Jacobs with capital, if he would move to Fort Wayne. Once there, Ethel's brother, P. Paul Mossman, provided additional management skills.

Magnet wire

Magnet wire or enameled wire is a copper or aluminium wire coated with a very thin layer of insulation. It is used in the construction of transformers, inductors, motors, speakers, hard disk head actuators, electromagnets, and other applications that require tight coils of insulated wire.

The wire itself is most often fully annealed, electrolytically refined copper. Aluminium magnet wire is sometimes used for large transformers and motors. Contrary to its name, the insulator is hardly ever enamel.

Smaller diameter magnet wire usually has a round cross section. This kind of wire is used for things such as electric guitar pickups. Thicker magnet wire is often square, rectangular or hexagonal (with rounded corners) in cross section, packing more efficiently and having greater structural stability and thermal conductivity across adjacent turns.

Insulation

Although described as "enameled", enameled wire is not, in fact, coated with either a layer of enamel paint nor with 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.