Quality inspection of copper rods is a crucial step in ensuring they meet the requirements for wire and cable production, primarily based on national standards such as "Copper Wire Rods for Electrical Use" (GB/T 3952-2016).
The main testing items include chemical composition and oxygen content analysis, requiring photoelectric emission spectrometry (e.g., YS/T 482-2005) to determine copper purity and impurity element content. According to GB/T 3952, grades T2 and TU2 require copper and silver content of not less than 99.95%, and have specific regulations regarding the content of impurities such as arsenic, bismuth, iron, and lead. Oxygen content is a key indicator distinguishing oxygen-free and low-oxygen copper rods. Oxygen-free copper rods require an oxygen content of no more than 0.02% (e.g., grade TU2 requires an oxygen content of no more than 0.0010%), while low-oxygen copper rods generally have an oxygen content of 200-400 ppm. Physical property testing includes tensile testing (e.g., GB/T 228.1) to detect tensile strength and elongation, and torsion testing (e.g., GB/T 239) to assess the material's plasticity and homogeneity. The core of electrical property testing is measuring the volume resistivity (ρ20) at 20℃, which is a key indicator for evaluating conductivity.
Metallographic inspection can be performed by measuring the average grain size (e.g., YS/T 347-2004) to observe the material's microstructure. Visual inspection requires checking whether the copper rod surface is round, smooth, and dimensionally uniform, and free from wrinkles, burrs, cracks, inclusions, and other defects harmful to its use.