Acetal enameled wire is one of the earliest developed varieties in the world. It was launched by Germany and the United States in 1930, and the Soviet Union also developed rapidly. There are two types of polyvinyl formal and polyvinyl acetal, which were successfully studied in China in the 1960s. Although this enameled wire has a low temperature resistance grade (105 ° C, 120 ° C), it is widely used in oil-immersed transformers due to its excellent high-temperature hydrolysis resistance. This characteristic has been recognized by various countries around the world, and there is still a small amount of production in China, especially acetal enameled flat wire used to make transposition wires for large transformers. Enamelled wire is the main raw material for products such as motors, appliances, and household appliances. Especially in recent years, the power industry has achieved sustained and rapid growth. The rapid development of household appliances has brought a wider range of applications for enameled wire, which has led to higher requirements for enameled wire. Therefore, it is inevitable to adjust the product structure of enameled wire, and the matching raw materials (copper, paint), enameling process, process equipment, and testing methods also urgently need to be developed and researched. Enamelled wire, sometimes also known as Magnetwire or Insulated wire, is a type of wire with a surface covered with insulating film. The conductor part of enameled wire is generally an undoped pure metal that has undergone annealing treatment, especially copper and copper. In some cases, copper alloys, gold, silver, nickel, stainless steel, and other materials are also used. Depending on the working voltage and temperature, enameled wire often uses polymers such as polyurethane, polyurethane, polyimide, and polyimide as insulation film materials. Enamelled wire is widely used in the production of electronics, electrical, medical devices, and semiconductors (such as sensors, transformers, coils, windings, implanted electrodes, chip interconnection leads, etc.), serving as a part of internal basic components or as a conductor medium for internal and external connections of components. When used as a medium for internal and external connections, the end of the enameled wire must achieve electrical contact with the metal terminals (such as inserts, pins, boxes, etc.) and meet certain requirements for mechanical properties, conductivity, and temperature fatigue resistance. Therefore, the connection performance between them directly affects the performance of the entire product