Interpretation of the Development Trend of Aluminum Wire -- Large Diameter Aluminum Wire

As an important part of the automobile, the Wire Harness accounts for 2%-3% of the total mass of the whole vehicle. With the increase of the proportion of the automobile electrical system, the wire harness as the electrical connection system becomes more and more complex, and its quality continues to increase. Therefore, the lightweight of the wiring harness is particularly important. According to statistics, the cable harness usage of an advanced car has reached 3km, and its weight is 20~30kg. Every 100km, the 25kg harness consumes about 50W of energy, which is equivalent to burning 0.1kg of fuel. The research shows that if the weight of the whole vehicle is reduced by 10%, the fuel consumption can be reduced by 8%. When the vehicle weight is reduced by 100kg, the fuel consumption per 100 km can be reduced by 0.3~0.6L, and the CO² emission can be reduced by about 5g/km.

Therefore, the future development trend of automotive Wiring Harness is thinner, lighter and thinner. Among them, the weight proportion of copper wire in automotive wiring harness is 75%, which is the main lightweight direction. At present, the main method to replace copper is aluminum instead of copper.

The weight of aluminum is about two-thirds lighter than that of copper. This lightweight material can reduce the overall weight of Cable Harness. Even considering the relationship between conductivity and density, aluminum wires with the same resistance are still about 50% lighter than equivalent copper wires.

Besides being lighter in weight, aluminum is also a basic conductive material with sufficient supply and easy access. Comparatively speaking, the resources of copper are limited, and it belongs to "investment type" metal. This means that the price of aluminum will be relatively stable and far lower than that of copper, and the cost will be well controlled.

From the perspective of installation cost, because aluminum conductor is relatively light, it does not need bridge and pipe threading in the installation process, which can save a lot of installation materials and save 20%-50% of installation cost compared with copper conductor.

Although aluminum conductor has the advantages of light weight and low price, it is rarely used in automobiles, especially aluminum conductor with small wire diameter. The main reason is that 0.35mm² and 0.5mm² copper wires are used the most in automotive wiring harness, and the existing technology can't completely solve the mechanical and electrical problems of small wire diameter aluminum wires, so the application of aluminum wires is limited. The specific technical difficulties are as follows:

The conductivity of aluminum wire is about 60% of that of copper wire, so the relative current carrying capacity is low. The mechanical strength of aluminum wire is only one third of that of copper wire, which will affect the pull-off force of terminal crimping. It is easy to form oxide film on the surface of aluminum wire, and the oxide layer has insulation characteristics, which will lead to the increase of crimping resistance.

The electrode potential difference between copper is about 2V. If the copper terminal is crimped to the aluminum wire, when the connection between copper and aluminum is in a humid environment and a chemical medium is dissolved in water vapor to form electrolyte, a galvanic cell with aluminum as the negative electrode and copper as the positive electrode will be formed, so that the aluminum with negative potential will corrode and dissolve, that is, electrochemical corrosion will occur.

Based on the above factors, if the two kinds of conductors have the same current carrying capacity, the quality of copper conductor is about twice that of aluminum conductor, and the cost of equivalent copper conductor is about 7 times that of aluminum conductor. It is worth noting that due to the relatively large cross-sectional area of aluminum conductor under the same conditions, the demand for insulation, protection and other materials of aluminum-cored cable increases, and the price advantage of aluminum conductor is correspondingly reduced. At present, the price of aluminum cable widely used in the market is only about 75% of that of copper core cable.

As we all know, the larger the cross-sectional area, the stronger the current carrying capacity. Therefore, by increasing the wire diameter, the current carrying capacity of aluminum wires can be improved. For example, 50 square meters of copper wires can be replaced by 70 square meters of aluminum wires. Even so, the weight can still be reduced by about 45% and the cost can be saved by more than half.