Failure analysis of wiring harness

From the perspective of using the Wire Harness, the function that should be achieved is: the conductive part of the contact part must be conductive, and the contact is reliable. Places where the insulating parts should not be conductive must be insulated reliably.

There are three common forms of fatal failures of wiring harnesses:

1. Poor insulation
The function of the insulator is to keep the contacts in the correct position and to insulate the contacts and the contacts, and between the contacts and the housing. Therefore, the insulating parts must have excellent electrical properties, mechanical properties and process forming properties. Especially with the widespread use of high-density and miniaturized terminal blocks, the effective wall thickness of the insulator becomes thinner and thinner. This puts more stringent requirements on insulating materials, injection mold accuracy and molding technology. Due to the existence of metal excess on the surface or inside of the insulator, surface dust, flux and other pollution and moisture, organic material precipitates and harmful gas adsorption film merge with the surface water film to form an ionic conductive channel, moisture absorption, mold growth, aging of insulation materials, etc. Will cause short circuit, leakage, breakdown, low insulation resistance and other poor insulation.

2. Poorly fixed problems
The insulator not only provides insulation, but also provides accurate centering and protection for the protruding contacts. It also has the functions of installation and positioning, and locking and fixing on the equipment. Poor fixation, the lighter will affect the reliable contact and cause instantaneous power failure, the more serious is the product disintegration. Disassembly refers to the abnormal separation between the plug and the socket, and between the pin and the socket due to the unreliable structure of the terminal in the plug-in state due to material, design, process and other reasons, which will cause the power transmission of the control system and Serious consequences of signal control interruption. Due to unreliable design, wrong material selection, improper selection of molding process, poor quality of heat treatment, mold, assembly, welding and other processes, improper assembly, etc., will cause poor fixation.

3. The problem of poor contact
The metal conductor of the wire harness is the core part of the terminal, which transmits the voltage, current or signal from the external wire or cable to the corresponding contact of the connector. Therefore, the contact must have an excellent structure, stable and reliable contact retention and good electrical conductivity. Due to the unreasonable structure design of the contact parts, wrong material selection, unstable molds, out-of-poor processing dimensions, rough surface, unreasonable surface treatment processes such as heat treatment and electroplating, improper assembly, harsh storage and use environment, and improper operation and use, all contact parts will be damaged. Contact parts and matching parts cause poor contact.

In addition, due to coating peeling, corrosion, bruising, plastic shell flashing, cracking, rough processing of contact parts, deformation, etc., the appearance is poor, due to the out-of-poor positioning and locking fit size, poor processing quality uniformity, and total separation force Poor interchange caused by major reasons. These types of faults can generally be found and eliminated in time during inspection and use.