What tests should be done for enamelled wire?

Enamelled wire is a main variety of winding wire, which is composed of conductor and insulating layer. The bare wire is annealed and softened, and then painted and baked for many times. However, it is not easy to produce products that meet both specification requirements and customer requirements. It is affected by raw material quality, process parameters, production equipment, environment and other factors. Therefore, the quality characteristics of various enamelled wires are different, but they all have four functions: mechanical function, chemical function, electrical function and thermal function.

1. Appearance inspection

The surface is lubricated, the color is uniform, and there is no paint tumor and white lubricant.

2. Dimension inspection

2.1 diameter of enamelled wire: refer to GB / t6109 for specifications, and inspection method: micrometer

2.2 conductor diameter: refer to GB / t6109 for specifications, and inspection method: micrometer

2.3 diameter of enamelled wire: refer to GB / t6109 for specifications, and inspection method: micrometer

2.4 conductor error value: refer to GB / t6109 for specifications,

3. Mechanical characteristics

3.1 elongation:

The specification refers to GB / t6109, inspection method: lengthening instrument

Calculation method: (length after stretching - length before stretching) / ratio of length before stretching;

3.2 snap:

According to the specification, the paint film shall be jerked at the speed of 2 meters per second, and the paint film shall be checked for cracks,

3.3 round bar winding:

Wrap the enamelled wires of different specifications and the corresponding copper rod for ten turns, and check that the paint film is free from cracking. The diameter of the copper rod shall refer to the requirements of GB / t6109;

3.4 thermal shock: place the wound enamelled wire in the oven (hung in the center of the oven) for 0.5 hours. The oven temperature shall meet the specification requirements corresponding to the enamelled wire, refer to GB / t6109, and check that the paint film is free of cracking after baking.

4. Electrical function

4.1 resistance:

Take 1m of the enameled wire to be inspected, scrape off the paint film at both ends, and measure the resistance of the enameled wire. The measured resistance value shall be within the resistance range required by GB / t6109; The standard temperature is 20 degrees, and the conversion formula is: resistance of 20 degrees / 234.5 + standard temperature = actual measured resistance / 234.5 + measured temperature;

4.2 salt bath test:

See salt bath test specification

4.3 breakdown voltage: take half of the 0.5m enameled wire once, cut half of the parts and scrape off the paint skin of four wires, and then half of the enameled wire twice, twist the half of the enameled wire into a twist condition (there are two wire ends at both ends) and test the high voltage of two wire ends at the same end with a high voltage instrument (high voltage specification: refer to national level 2 specification).