Copper rod is the main raw material of cable industry, and there are two main production methods: continuous casting and rolling method and upward drawing continuous casting method. The oxygen content and appearance of copper rods are different due to the different processes of producing copper rods. The oxygen content of copper rod produced by updraft continuous casting method is less than 10ppm, so it is called oxygen free copper rod. 

Low oxygen copper rod 

Process defects: 

The molten copper was melted while adding, and the molten copper water was not fully reduced. The oxygen can not be isolated in the whole process of melting and discharging copper water. So the oxygen content is very high. Molten copper fuel is usually gas. In the process of gas combustion, it will directly affect the chemical composition of molten copper, such as sulfur and hydrogen. 

Advantages of the process: 

a. The output is high, and the output of small units can reach 10-14 tons per hour. 

b. Plum blossom type is adopted for copper rod unloading, which is convenient for wire drawing machine. 

c. Take up weight is large, generally up to 4 tons per plate. 

Grade and characteristics of low oxygen copper rod: 

There are three grades of low oxygen copper rods, T1, T2 and T3. The low oxygen copper rods are all hot-rolled, so they are soft rods, code named R. 

a. T1: using high purity electrolytic copper as raw material (copper content is more than 99.9975%) to produce low oxygen copper rod. 

b. T2: using 1 # electrolytic copper as raw material (copper content is more than 99.95%) to produce low oxygen copper rod. 

c. T3: using 2 # electrolytic copper as raw material (copper content is more than 99.90%) to produce low oxygen copper rod. As there are few high-purity electrolytic copper and 2 # electrolytic copper on the market, generally 1 ᦇ electrolytic copper is used as raw material, so the general low oxygen copper rod grade is: T2R. 

Oxygen free copper rod 

Oxygen free copper rod is pure copper without oxygen and deoxidizer residue. But in fact, it still contains a very small amount of oxygen and some impurities. According to the standard, the content of oxygen is not more than 0.02%, the total content of impurities is not more than 0.05%, and the purity of copper is more than 99.95%. Generally, electrolytic copper is used for production, and its resistivity is lower than that of low oxygen copper rod. Therefore, oxygen free copper rod is more economical in the production of products with strict resistance requirements. According to the oxygen content and impurity content, oxygen free copper rods are divided into TU1 and TU2 copper rods. The purity of TU1 oxygen free copper rod is 99.99%, and the oxygen content is not more than 0.001%; the purity of TU2 oxygen free copper rod is 99.95%, and the oxygen content is not more than 0.002%. 

Difference between low oxygen copper rod and oxygen free copper rod 

Due to the different manufacturing methods, low oxygen copper rod and oxygen free copper rod have their own characteristics. 

a. On the inhalation and removal of oxygen and its state of existence However, the oxygen content of copper in the deoxidized rod is below 1-450 ppm. The oxygen content in the oxygen free copper is very low, so the microstructure of the copper is uniform, and the single phase structure is beneficial to the toughness. 

b. The difference between the amount of impurities and the existing hot rolling defects. The tensile property of oxygen free copper rod is superior to that of low oxygen copper rod in all wire diameters. In addition to the above structural reasons, the oxygen content of oxygen free copper rod is less, the oxygen content is stable, there is no defect that may be produced by hot rolling, and the oxygen content instability will directly affect the performance of the rod. If the oxide on the surface of the rod can be made up in the continuous cleaning of the subsequent process, it is more troublesome that a considerable amount of oxide exists in the "subcutaneous", which has a more direct impact on the wire breakage.

c.  The toughness of low oxygen copper rod is different from that of oxygen free copper rod. Both of them can be pulled to 0.015 mm, but the distance between the filaments of low temperature grade oxygen free copper in cryogenic superconducting wires is only 0.001mm. 

d. The wire making process of low oxygen copper rod is different from that of oxygen free copper rod. The wire making process of low oxygen copper rod can not be transferred to that of oxygen free copper rod, at least the annealing process of the two is different. Because the softness of the wire is deeply affected by the material composition, rod making, wire making and annealing process, it can not be simply said that the copper with low oxygen content or oxygen free copper is soft and hard.