What is magnet wire varnish?

magnet wire varnish coats copper and aluminum round and flat wires of engines, transformers, generators and electrical measuring instruments. It is cured to the surface of the wire at high temperature. The main function of the final coating is electrical insulation. Magnet wire coating can also be called main insulation. The coated wire may sometimes be referred to as “magnet wire”.

Wires insulated with enameled wire varnish
The enameled wire paint coats up to 30 layers of copper and aluminum wires to provide electrical insulation and help avoid short circuits in the coil. Such enameled wire paint must also have excellent chemical resistance and high temperature resistance, must have excellent adhesion with copper or aluminum wires, and also have excellent mechanical stability.

In some cases, such as for motors driven by frequency converters, a suitable insulation layer should be able to resist partial discharges that may cause short circuits and malfunctions in the engine.

Depending on the application, the coated wire is also very different. Some wires may be thinner than a human hair, such as watch electronic components. However, the diameter of the round or flat wire of the large electric motor in the wind turbine can reach several millimeters.

According to the shape and diameter of the coated wire, different coating methods should be adopted for the enameled wire paint. Horizontal or vertical coating, or coating using a mold or felt is a typical enameled wire paint film method.

Enameled wire paint can be composed of different chemical components, including polyurethane, polyester, polyesterimide and polyamideimide. The solid content range is about 8% to 60% (1g/1h/180°C), and the viscosity range is between 30 to 60000mPas (25°C).

Mold coating Wire Enamel Insulating Varnish
Polyurethane enameled wire coating (PUR)
Polyurethane enameled wire has good solderability at 375°C, and a special formula can provide excellent crack resistance and pinhole resistance. This type of enameled wire paint is mainly used for small transformers, timers, relays, small motors, solenoid valves, clock coils, watch coils, flyback transformers and magnetic heads.

Solderable Polyesterimide Enameled Wire coating (PEI)
Solderable polyester imine enameled wire paint can be widely used in the electromagnetic wire of relays, small transformers, small motors, contactors, ignition coils and automobile coils.

Seck Modified Polyester Enameled Wire coating(TPE)
Seck modified polyester enameled wire paint is used as a top coat for aluminum and copper wires. It has good mechanical resistance, electrical resistance, chemical resistance and heat resistance.

Seike Polyesterimide Enameled Wire coating (TPEI)
Seike polyester imine wire enamel has high heat resistance, good mechanical resistance, electrical resistance and chemical resistance. This type of enameled wire paint is widely used in wires for motors, refrigeration equipment, transformer coils and fluorescent lamp ballasts.

One of Axalta Sec’s polyester-imide wire enamels-Voltatex 7200 series is solderable when the temperature reaches 450℃ or higher. This type of coating is particularly suitable for small motors to connect the coil to the collector. The coated magnet wire has good elasticity, dielectric properties and mechanical properties. Due to its excellent mechanical properties, high heat resistance and good chemical resistance, Voltatex 7300 AX is suitable for coating wires that are widely used in small transformers, cooling polymers and electrical ballasts.

How to avoid corona discharge?
Corona discharge can occur in high-voltage applications in electrical equipment, such as variable frequency motors, transformers, high-voltage rectifiers, generators, ignition coils, windmills, hybrid motors, elevators or pump motors. The globally patented Voltron® system consists of a top coat and a top coat-Voltatex 7700 and Voltatex 8200 series. Voltron can only be used under certain conditions. For more information, please contact us.

Voltron enameled wire varnish
Voltron’s embedded nanotechnology is high pressure resistant

Polyamideimide wire enamel (PAI)
The polyamide-imide wire enamel can be double-coated or single-coated, both of which have good mechanical properties and chemical resistance. In addition to the classic polyamideimide, Axalta also sells enameled wire paint while providing integrated lubricants to increase the winding speed. Such products are particularly suitable for coating wires for motors, refrigeration equipment, transformer coils and fluorescent lamp ballasts. For flat wire coating, large transformers and generators, the Voltatex 8300 series based on polyamideimide is recommended. This product can be used as an elastic top coat, combined with polyester or polyester imine top coat to improve the mechanical, chemical and heat resistance of the coating. Under certain circumstances, the Voltatex 8300 series can also be used as a single coating for flat wire coating.

Acetal enameled wire varnish (PVF)
Acetal enameled wire paint is suitable for heavy round conductors and rectangular conductors. The product has excellent mechanical stability, excellent copper adhesion and resistance to transformer oil. Because this type of high-end enameled wire paint has excellent mechanical properties, it is mainly used for large generators and transformers. In addition to good dielectric properties, this type of enameled wire paint also exhibits excellent chemical resistance, which makes the coated wire suitable for airtight applications and oil-immersed transformers that meet the IEC60 851-4 standard. This product is also suitable for the production of CTC flat wire.

Self-bonding enameled wire coating (SB)
Self-adhesive wire enamel based on polyvinyl acetal and polyamide is used to stabilize the coil. This product is mainly used to coat instrument coils, voice coils, speakers, small motors and sensors.