In today's ubiquitous power, communication, and electronic devices, cables silently support the operation of modern society as "carriers of energy and information". Copper rod is the main raw material in the cable industry, and there are two main production methods - continuous casting and rolling method and upward continuous casting method. Due to the different production processes of copper rods, the oxygen content and appearance of the copper rods produced are different.

Oxygen content: the first watershed

The oxygen content of Low Oxygen Copper Rod is usually between 200-500ppm (parts per million), sometimes even up to 700ppm or more. This type of copper rod is produced using the continuous casting and rolling process (SCR process), which inevitably inhales a small amount of oxygen during the liquid stage of copper.

Oxygen Free Copper Rod is completely different, with its oxygen content strictly controlled below 10ppm, and high-end products can even be as low as 1-2ppm. This ultra-high purity is achieved through upwelling or vacuum melting technology, isolating oxygen throughout the entire production process.

Figuratively speaking, the difference in oxygen content between the two is equivalent to having 200-500 people in a low oxygen copper pole in a standard classroom, while there are less than 10 people in an anaerobic copper pole, and possibly only 1-2 people. This magnitude difference brings about a huge performance gap.

Performance showdown

electrical conductivity

Oxygen free copper rod: conductivity close to 101% IACS (International Annealed Copper Standard), approaching the theoretical limit value

Low oxygen copper rod: conductivity of approximately 98% -99% IACS

Although the numerical difference is only 2% -3%, this small difference is crucial in high-frequency signal transmission and precision electronics. The extremely low oxygen content in oxygen free copper reduces electron scattering, making current transmission smoother.

ductility

Oxygen free copper rod: With a uniform single-phase structure, it is not easy to crack during cold processing, especially suitable for drawing fine wires with a diameter less than 0.05mm

Low oxygen copper rod: Oxygen exists in the form of cuprous oxide at grain boundaries, which may cause work hardening and require intermediate annealing treatment

mechanical strength

Low oxygen copper rod: Thanks to the diffusion strengthening effect of oxygen, the tensile strength is higher (about 220-250 MPa)

Oxygen free copper rod: slightly lower tensile strength (about 200-220 MPa), but better flexibility

In terms of resistivity, oxygen free copper is about 0.0165 Ω· mm 2/m, low oxygen copper is about 0.0168 Ω· mm 2/m, and regenerated copper is as high as 0.0185 Ω· mm 2/m or more. These subtle differences can be amplified in long-distance power transmission or precision electronic applications.

Manufacturing Process: The Game between Cost and Technology

Low oxygen copper rod - efficiency priority continuous casting and rolling

Adopting continuous casting heating rolling process (SCR process)

Short process, high efficiency, low energy consumption

Loose requirements for raw materials and high utilization rate of scrap copper

Low production cost, priced 10% -15% lower than oxygen free copper rods

Oxygen free copper rod - precision manufacturing with continuous improvement

Adopting the upward drawing method or vacuum melting technology

Isolation of oxygen throughout the process, high equipment investment

The purity requirements are strict, and the scrap copper needs to be deeply purified

Significant increase in production costs

The low oxygen copper rod has undergone hot rolling, and its structure belongs to the hot working structure. The original casting structure has been broken. The oxygen free copper rod retains the casting structure and has relatively coarse grains, which is why oxygen free copper requires a higher annealing temperature - its recrystallization temperature is higher.

Selection Guide

1. Performance priority: Choose anaerobic transmission for high-frequency signal transmission, and prioritize low oxygen transmission for strength requirements

2. Cost budget: When mass production is carried out and conductivity requirements are not extreme, low oxygen copper rods have a higher cost-effectiveness

3. Processing difficulty: Micro wire processing prioritizes oxygen free copper to avoid the risk of wire breakage

Special reminder: The production processes of the two types of copper rods are not interchangeable, especially the annealing process, which has significant differences. The flexibility of the wire is deeply influenced by the material composition, rod making, wire making, and annealing processes, and cannot be simply stated as which type of copper is softer or harder

Conclusion

There is no absolute 'superiority or inferiority', only precise 'adaptation'.

When we see the criss crossing cable network again, perhaps we will have a better understanding - those copper cores hidden under the insulation layer, whether low oxygen or oxygen free, are precise choices made by engineers based on scientific principles and economic considerations. It is these invisible details of material science that support visible modern civilization.

Article source: Internet

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