Automotive wiring and cables constitute the fundamental network of the vehicle’s wiring harness, with approximately 80% of the harness’s weight attributable to the weight of these wires. The ability to control costs associated with automotive wiring has a significant impact on the overall cost management for wiring harness companies.
Automotive wires come in a multitude of types, characterized by their soft structure and the extensive use of high-polymer materials for insulation.
Due to the unique demands of automotive applications, these wires are subject to elevated performance requirements in terms of insulation wall thickness, flexibility, heat resistance, cold resistance, oil resistance, abrasion resistance, waterproofing, flame retardancy, and environmental compliance.
Furthermore, the variety of vehicle models and regional applications necessitates differing temperature and voltage ratings for automotive wiring.
Classification of Automotive Wiring
Automotive wires can be classified based on performance, structure, and application.
- Voltage Ratings: Automotive wiring can be divided into low-voltage wires and high-voltage cables for electric vehicles. The basic structure and naming conventions of low-voltage wires are illustrated in Figure 1-10.
- Structural Types: Wires can be categorized into single-core unshielded wires (also known as primary wires), multi-core unshielded cables, single-core shielded cables (commonly referred to as coaxial cables), and multi-core shielded cables. Additionally, it is common practice in the automotive wiring industry to twist two low-voltage wires together to effectively mitigate electromagnetic interference, forming twisted pairs or stranded wires.
- Application in Circuits: Wires can also be classified based on their function within the electrical circuit, distinguishing between signal wires, which convey sensor and control information, and power wires, which transmit electrical power within the system.
- Temperature Ratings: The low-temperature rating for automotive wiring is typically -40 degrees Celsius. High-temperature ratings can vary, including classifications at 85, 80, 100, 105, 125, 150, 175, 180, 200, 225, and 250 degrees Celsius.
- Insulation Material Types: Wires can be categorized into those insulated with thermoplastic materials and those insulated with thermosetting materials.
- Insulation Thickness: Wires can be classified based on insulation thickness into standard, thin, ultra-thin, and extremely thin types, as shown in Figure 1-11.
- Flame Retardancy and Environmental Properties: Wires can also be classified according to their flame retardant and environmental characteristics into low-smoke, halogen-free types and halogen-containing types.
- Color Coding: Automotive wires may be categorized by color, including monochromatic, bicolor, and tricolor options. The colors typically serve to distinguish their functions within the circuit. In recent years, with advancements in equipment automation and wire marking technology, automotive manufacturers and wiring harness companies have increasingly adopted marking techniques on wires of the same color to denote their specific uses, thereby reducing the variety of wire types and alleviating inventory pressures.
Standards for Automotive Wiring
The production and testing standards for automotive wiring encompass international standards, national standards, and internal control standards set by automotive manufacturers.
Currently, widely recognized standards include Japanese, German, Chinese, and American wire standards, as well as internal control standards from companies like Volkswagen and Hyundai.
The primary differences between these standards lie in specifications for conductor cross-sectional areas, material usage and grading, insulation layer thickness requirements, and focal points for insulation materials, such as heat resistance and corrosion resistance.
Specifications for Automotive Wiring
Common specifications for automotive wiring include nominal cross-sectional areas of 0.35 mm², 0.50 mm², 0.75 mm², 1.00 mm², 1.50 mm², 2.00 mm², 2.50 mm², 4.00 mm², and 6.00 mm². In Japanese standards, frequently used specifications include nominal cross-sectional areas of 0.30 mm², 0.50 mm², 0.85 mm², 1.25 mm², 2.00 mm², 2.50 mm², 4.00 mm², and 6.00 mm².
Different specifications correspond to varying permissible load current values, suitable for different power-consuming devices. Positive power wires are typically used as standalone automotive wires, with diameters ranging from a few to several dozen square millimeters. These substantial wires are generally not incorporated directly into the automotive wiring harness assembly.
Low-Voltage Wires and High-Voltage Cables for New Energy Vehicles
Low-voltage automotive wires refer to those used within the automotive sector, with voltage ratings below 600 volts, and are currently the most widely utilized.