Magnet wire: insulated wire used to make coils in electrical products

Magnet wire is an insulated wire used to make coils or windings in electrical products. Also called winding wire. Magnet wire must meet a variety of usage and manufacturing process requirements. The former includes its shape, specifications, can work at high temperature for short and long-term, and withstand strong vibration and centrifugal force at high speed in certain occasions, withstand corona and breakdown under high voltage, and chemical resistance under special atmosphere. Corrosion, etc.; the latter includes the requirement to withstand stretching, bending and abrasion during winding and embedding, as well as swelling, erosion, etc. during dipping and drying.

Magnet wires can be classified by their basic composition, conductive core, and electrical insulation. Generally, it is divided into enameled wire, wrapped wire, enameled wrapped wire and inorganic insulated wire according to the insulating material and manufacturing method used for the electrical insulating layer.

The purpose of magnet wire

There are two uses of magnet wire:

①General purpose, mainly used in motors, electrical appliances, instruments, transformers, etc., to generate electromagnetic effects by winding coils, and use the principle of electromagnetic induction to achieve the purpose of converting electrical energy and magnetic energy;

②Special purpose, used in electronic components, new energy vehicles and other fields with special characteristics requirements, such as fine electronic wires are mainly used for the transmission of information in the electronics and information industries, and special wires for new energy vehicles are mainly used in the production of new energy vehicles manufacture.

Classification of magnet wire

enameled wire

The conductor is coated with the corresponding paint solution, and then the solvent is evaporated and the paint film is cured and cooled. Enameled wire can be divided into polyester enameled wire, polyesterimide enameled wire, polyamideimide enameled wire, polyimide enameled wire, polyesterimide/polyamideimide enameled wire, corona-resistant enameled wire, and oily enameled wire according to the insulating paint used. Paint, acetal paint, polyurethane enameled wire, etc. Sometimes it is also classified according to the particularity of its use, such as self-adhesive enameled wire, refrigerant resistant enameled wire, etc.

The earliest enameled wire is oily enameled wire, which is made of tung oil and so on. The paint film has poor wear resistance and cannot be directly used in the manufacture of motor coils and windings. It needs to be wrapped with cotton yarn when used. Later, the polyvinyl formal enameled wire came out, and its mechanical properties were greatly improved, and it could be directly used in motor windings, and it was called high-strength enameled wire.

With the development of weak current technology, self-adhesive enameled wires have appeared, which can obtain coils with better integrity without dipping and baking. However, its mechanical strength is poor, and it can only be used in micro motors and small motors. In addition, in order to avoid the trouble of removing the paint film before welding, the straight-solderable enameled wire has been developed.

Due to the increasingly wide application of enameled wire and the increasingly stringent requirements, composite enameled wire has also been developed. The inner and outer paint films are composed of different polymer materials, such as polyesterimide/polyamideimide enameled wires.

Wrapped wire

An important variety in winding wire. In the early days, cotton yarn and silk, called yarn-covered wire and silk-covered wire, were used in motors and electrical appliances. Due to the large insulation thickness and low heat resistance, most of them have been replaced by enameled wires. Currently only used as high frequency winding wire. In the large and medium-sized winding wires, when the heat resistance level is high and the mechanical strength is high, the glass wire wrapped wire is also used, and the appropriate adhesive paint is used during manufacture.

Paper-covered wire still occupies a considerable position in the wrapped wire, mainly used in oil-immersed transformers. The oil-paper insulation formed at this time has excellent dielectric properties, low price and long service life. Paper-covered wire is a wire that is annealed after being extruded or drawn by an oxygen-free copper rod or an electrical round aluminum rod, and then wrapped with two or more layers of insulating paper on the copper (aluminum) conductor (including Winding wire for telephone paper, cable paper, high-voltage cable paper, inter-turn insulating paper, etc.), suitable for oil-immersed transformer coils and other similar electrical appliance winding wires. NOMEX paper-covered wire is a wire extruded by an oxygen-free copper rod or an electrical round aluminum rod through a mold of a certain specification, and then wrapped by the NOMEX insulating paper produced by DuPont in the United States. It is mainly used for transformers, electric welding machines. , windings of electromagnets or other similar electrical equipment products. The electrical bare copper (aluminum) wire produced by the extrusion process is the most ideal material for the production of cable paper-covered wire.

In recent years, the film wrapping wire has developed rapidly, mainly including polyester film and polyimide film wrapping wire.

Recently, there is also a mica tape wrapped polyester imide film wrapped copper flat wire for wind power generation.

Insulated wire

When the heat resistance level requirements exceed the limit of organic materials, inorganic insulating paints are usually applied. Existing inorganic insulating wires can be further classified into glass film wires, oxide film wires and ceramic wires.

other

There are also combination wires, transposed wires, etc.