We will strictly follow the requirements when manufacturing products. After the product is manufactured, whether its appearance, size and performance meet the technical standards of the product and the requirements of the technical agreement of the user must be judged through inspection. After measurement and testing, compared with the technical standards of the product or the technical agreement of the user, if the product meets the requirements, it is qualified; otherwise, it is unqualified. Passing the inspection can reflect the stability of the enameled wire product quality and the rationality of the material process. Therefore, the quality inspection has the functions of checking, preventing and identifying. The content of enameled wire inspection includes: appearance, size inspection measurement and performance test. The properties include: mechanical properties, chemical properties, thermal properties and electrical properties. Now we mainly explain the heat resistance performance.
Heat resistance performance: including thermal shock and softening breakdown test. The thermal shock of the enameled wire is the ability of the paint film of the enameled wire to withstand heat under the action of mechanical stress. Factors affecting thermal shock: paint, copper wire, enamelling process.
Thermal shock reflects the ability of a specimen to withstand the temperature after being stretched and/or coiled or bent on a round bar.
1.1 Sample Preparation
1.1.1 Park Line
Specimens shall be prepared as follows:
- Forenameled wires whose conductor nominal diameter is less than or equal to 1.600mm, according to the provisions in 5.1.1 of GB/T4074.3-2008;
– For enameled wires with conductor nominal diameter greater than 1.600mm, according to GB/T4074.3-2008 5.2;
all
For film-wrapped wire with conductor nominal diameter less than or equal to 1.600mm, according to GB/T4074.3-2008 5.1.1
Regulation;
For the film-wrapped wire with conductor nominal diameter greater than 1.600mm, according to GB/T4074.3-2008 in 5.5.4.
1.1.2 Flat wire
Prepare the sample according to the provisions in 5.1.2 of GB/T4074.3-2008, but only the wide side can be bent (with the narrow side size).
1.2 Test procedure
Place the sample in a forced-air oven and heat for 30 in, at a temperature of ±5°C as specified in the relevant product standard. Remove the test from the oven
Cool the sample to room temperature, and then use the magnifying glass specified in Table 1 to check whether the insulation is cracked.
1.3 Test results
For round wire, test three samples; for flat wire, test two samples. Any detected cracks should be recorded.
The softening and breakdown performance of the enameled wire is a measure of the ability of the enameled wire paint film to withstand thermal deformation under the action of mechanical force, that is, the ability of the compressed paint film to soften and soften at high temperature. The heat softening and breakdown performance of enameled wire paint film depends on the molecular structure of the paint film and the force between molecular chains.
Therefore, the enameled wire requires uniform, smooth, and complete coverage (few pinholes). Wire diameter and paint film thickness should comply with national standards.
