What is automotive wiring harness
The automotive wiring harness is the main network of the automotive circuit. Without the wiring harness, there would be no automotive circuit. The wiring harness refers to the contact terminal (connector) made of copper material, which is crimped with the wires and cables, and then the insulator is plastic-pressed on the outside or a metal shell is added, etc., and the wiring harness is bundled to form a component connecting the circuit. The wiring harness industry chain includes wires and cables, connectors, processing equipment, wiring harness manufacturing and downstream application industries. The wiring harness is widely used and can be used in automobiles, household appliances, computers and communication equipment, various electronic instruments and meters, etc. The body wiring harness connects the entire body and is generally H-shaped.
Main specifications and performance requirements of automotive wiring harnesses
1. Cross-sectional area of the conductor
Select the cross-sectional area of the wire according to the load current of the electrical equipment. The general principle is that electrical equipment that works for a long time can use wires with a current carrying capacity of 60% of the actual current, and electrical equipment that works for a short time can use wires between 60% and 100% of the actual current. At the same time, the voltage drop in the circuit and the heating of the wire should also be considered to avoid affecting the electrical performance of the electrical equipment and the allowable temperature of the wire. In order to ensure a certain mechanical strength, the cross-sectional area of the low-voltage wire is generally not less than 1.0mm².
There are color and number characteristics on the automobile circuit. With the increase of automobile electrical equipment, the number of wires is also increasing. In order to facilitate the identification and maintenance of automobile electrical equipment, the low-voltage wires in the automobile circuit are usually composed of different colors and marked with color letter codes on the automobile electrical circuit diagram.The color code of the wire is usually marked on the automobile circuit diagram (indicated by one or two letters). The colors of the wires in the car are generally different. There are two commonly used selection principles: single color and double color. For example: red (R), black (B), white (W), green (G), yellow (Y), black and white (BW), red and yellow (RY). The first color of the double color wire is the main color, and the second color is the secondary color.3. Physical properties of wire(1) Flexibility: The wires between the door and the body of the vehicle should be made of wires with good flexibility.(2) High temperature resistance: Wires used in high temperature areas are generally coated with vinyl chloride or polyethylene, which have good insulation and heat resistance.(3) Shielding performance. In recent years, the number of electromagnetic shielding cables used in weak signal circuits has continued to increase.(1) Cable half-folding wrapping method, applying insulating paint and drying to increase the strength and insulation performance of the cable.(2) The new wiring harness is partially wrapped with plastic and placed in a plastic corrugated tube with a side cut, making it stronger, more protective, and easier to find line faults.
Wiring Harness Production Process
The first workstation of wire harness production is the wire opening process. The accuracy of the wire opening process is directly related to the entire production progress. Once an error occurs, especially if the wire opening size is too short, it will lead to rework of all workstations, which is time-consuming and labor-intensive and affects production efficiency. Therefore, when preparing the wire opening process, it is necessary to reasonably determine the wire opening size and stripping size according to the requirements of the drawing.The second station after opening the wire is the crimping process. The crimping parameters are determined according to the terminal type required by the drawing, and the crimping operation instructions are prepared. For special requirements, they need to be noted in the process documents and the operators need to be trained. For example, some wires need to pass through the sheath before they can be crimped. It is necessary to pre-install the wires and then return from the pre-installation station for crimping; there are also piercing crimping methods that use special crimping tools. This crimping method has good electrical contact performance.Next is the pre-assembly process. First, the pre-assembly process operation manual must be compiled. In order to improve the efficiency of the final assembly, complex wiring harnesses must be equipped with pre-assembly stations. The rationality of the pre-assembly process directly affects the efficiency of the final assembly and also reflects the technical level of a technician. If the pre-assembly part is assembled less or the assembled wire path is unreasonable, it will increase the workload of the final assembly personnel and slow down the speed of the assembly line, so the technicians should often stay on site to continuously summarize.The last step is the final assembly process. According to the assembly table designed by the product development department, the tooling equipment and material box specifications can be designed, and all assembly sleeves and accessory numbers can be affixed to the material box to improve assembly efficiency. The assembly content and requirements of each station are compiled to balance the entire final assembly station to prevent a small workload from slowing down the entire assembly line.
Wiring harness components
Automotive wiring harnesses consist of wires, terminals, coverings, connectors and other parts.Wires are the main component of the wiring harness, usually called conductors. They are the main part of the wiring harness and their main function is to carry the current required by the load. The important parameter of the wire is the current carrying capacity, which is affected by the wire diameter (cross-sectional area of the wire conductor), wire length, conductor resistivity and ambient temperature.
Connectors are also called connectors, CONNECTOR, or plug-in connectors. Connectors are indispensable components for connecting wire harnesses with other electrical equipment. They are divided into wire harness end connectors and appliance end connectors.We often hear about male connectors (male end for short) and female connectors (female end for short). The connector where the male terminal is located is called a male connector, and the connector where the female terminal is located is called a female connector. The ones at the end of our wiring harness are usually female connectors.
Connectors can be divided into two categories: waterproof and non-waterproof. At the beginning of the design, PIN pins of different widths are selected according to the current that each PIN pin needs to carry, and then cavities for accommodating different PIN pins are formed on the connector, thus forming a housing that accommodates multiple PINs.
(1) CPA-molded case secondary locking mechanism Connector Position Assurance:
Its function is to ensure that the buckle of the locking mechanism will not be easily withdrawn after the plastic shell and the electrical interface are assembled in place. Due to its special function, CPA must be designed to ensure the operability and recognizability of workers. This requires that CPA must be an independent mechanism on the plastic shell and must have a special color mark.(2) Waterproof sealing ring:There are two types of waterproof sealing mechanisms, one for sealing between plastic shells and the other for sealing terminal lead wires.(3) TPA-Terminal secondary locking structure Terminal Position Assurance:Not all terminals require a secondary locking structure. VW requires that TPA should be used for terminals with a width of 2.8mm (including 2.8). To ensure that workers in the wiring harness factory can install the terminals easily, the color of TPA must be recognizable and there must be a clear feel during assembly. To ensure that TPA does not automatically enter the locked position during transportation of the plastic shell to the wiring harness factory, an anti-locking mechanism is required on TPA.
The main function of the wire harness wrap is to protect the wire harness. According to the different materials of the wrap, the types of wrap mainly include corrugated tubes, PVC tape, cloth-based tape, flannel tape, sponge tape and aluminum foil tape.Due to the difference in materials, the material properties of different wrappings are also inconsistent. Correspondingly, their application conditions and methods in the wiring harness assembly are also inconsistent. The specific selection should be based on the specific use environment of the wiring harness and its wear resistance and heat resistance.
Unlike other parts on other cars, the wiring harness is a flexible part and cannot be delivered in a predetermined shape. Therefore, in order to constrain the layout path of the wiring harness on the vehicle, additional parts need to be added to fix the wiring harness. These additional parts are the wiring harness fixtures, which play the role of fixing the wiring harness and constraining the wiring harness layout path.Wire harness fixtures include cable ties, clips, rubber sheaths, wire harness brackets, etc. Depending on the installation environment of the wire harness, such as the installation space, temperature requirements, and waterproof requirements, the shape and material of each wire harness fixture are not consistent. Even so, wire harness fixtures show a trend of standardization and are one of the components that are easier to implement in the platform selection of wire harnesses.
Wiring harness accessories refer to other smaller products on the wiring harness assembly, such as product labels, fuse clips, etc. on the wiring harness assembly.
