Importance of Testing for Enamelled Magnet Wires

Enamelled magnet wire is a type of copper (or aluminum) wire coated with a thin layer of insulating enamel. It’s primarily used in the manufacture of transformers, motors, generators, inductors, etc. To ensure enamelled magnet wire performs reliably, a series of tests are conducted to evaluate its quality, durability, and compliance with standards.

Below are the key characteristics and associated tests for enamelled magnet wire:
1. Pinhole: A small hole in the paint film that cannot be visually distinguished by a certain length of test material. The paint film continuity test is also called the pinhole test. Its main influencing factors are: raw materials; operating process; equipment.
2. Flexibility: Whether the paint film cracks or whether pinholes are produced when winding or stretching. The main factors affecting the elongation and rebound angle of enamelled magnet wire are: wire quality; external force influence; degree of annealing.
3. Adhesion: Whether the paint film cracks when stretched rapidly.
4. Wear (damage) resistance: When the paint film is worn by an abrasion tester, the number of times the conductor is worn or the wear damage value is seen.
5. Insulation breakdown voltage: Twist two strands of enamelled magnet wire into one, apply voltage between the conductors, and measure the breakdown voltage of the paint film.
Main factors affecting the breakdown voltage: paint film thickness; paint film roundness; curing degree; external impurities in the paint film.
The main factors affecting DC resistance are: annealing degree and enameling equipment.
6. Aging resistance: When heated under specified conditions, the paint film is expressed by whether pinholes or insulation damage voltage values are generated.
7. Softening resistance: Heat the crossed enamelled magnet wire under specified conditions, and after power is turned on, see whether there is a short circuit or the temperature value of the short circuit. Or twist two strands of enamelled magnet wire and heat them under specified conditions to see if the paint film is abnormal.
8. Heat shock resistance: When elongated or wound, heat under specified conditions to see if the paint film cracks.
9. Solvent resistance or chemical resistance: When immersed in solvents or chemicals, the state of the paint film is expressed by the nail method or pencil method.
10. Oil resistance: Immerse in insulating oil under specified conditions, and the state of the paint film is expressed by the nail method or pencil method.
11. Direct solderability: According to the specified conditions, temperature and solder, see if the solder is evenly attached. The main factors affecting direct sold solderability are: process and paint.
12. Conductor resistance: measured with a conductor resistance tester and converted into a value at 20°C.

Several industry standards define the tests and criteria for evaluating enamelled magnet wire:
IEC 60851: Specifies test methods for magnet wires.
NEMA MW 1000: Standards for magnet wire, including requirements for different types of enamel insulation.
ASTM D2307: Standard test method for thermal endurance of enamelled magnet wire insulation.
These standards ensure that enamelled magnet wires meet quality requirements for safety, durability, and performance in diverse applications.

The enamelled magnet wires we produce meet the above standards. If you need them, please contact us immediately.