Mechanical and Environmental Performance of Automotive Wire Harness Connectors

1. Mechanical performance of wire harness connectors

The mechanical performance of the connector includes insertion and extraction force, mechanical endurance, and the matching force and separation force between the terminal and the sheath, which plays an important role in the selection of wire harness connectors.

As the name suggests, insertion and extraction force refers to the force required to separate the plug and socket. Under the premise of ensuring normal power supply, the smaller the insertion and extraction force, the better. Too  insertion and extraction force will easily lead to the plug cannot be pulled out smoothly, while too small  insertion and extraction force will lead to poor contact. Generally, the maximum insertion and extraction force of automotive connector is no more than 75N. Therefore, under the condition of ensuring normal power transmission, the smaller the insertion and extraction force, the better. Mechanical endurance refers to the number of insertions and extractions.

The mechanical endurance of a general electrical connector is usually 500-1000 times, while the automotive connector can normally be inserted and extracted for 10 times, the silver-plated terminal can normally be inserted and extracted for 30 times, and the gold-plated terminal can normally be inserted and extracted for 100 times. The matching force between the terminal and the sheath is affected by the wire diameter of the terminal crimping. When the wire diameter is less than 1mm², the matching force should not be less than 15N, and when the wire diameter is more than 1mm², the matching force should not be less than 30N.

The separation force between the terminal and the sheath is related to the specifications of the connector. For connectors with specifications below 2.8 and above 2.8, the separation force should be greater than 40N and 60N respectively.

2. Environmental performance of wire harness connectors

The use of automotive wire harness connectors is very extensive, but different parts of the car are often exposed to very different environments. Therefore, environmental factors play a crucial role in the selection of automotive connectors. Environmental factors mainly include temperature, humidity, waterproof and dustproof, etc. The environmental temperature is divided into five levels, and the experimental temperature is generally slightly higher than the environmental temperature.

When selecting the wire harness connectors, firstly we should determine the corresponding temperature level according to the location, and then make the most reasonable choice according to the sheath and terminal materials. When using wire harness connectors, the humidity should not be too high, as it may cause short circuits in humid environments. Therefore, sealed connectors should be selected in a humid environment.

The required waterproof level varies depending on the different positions of the car, the level of air humidity and water interference. Generally, waterproof sheaths should be used in the engine compartment, chassis and lower part of the enine, and the bottom part of the seat and door. Non-waterproof connectors can be used in positions such as the inside of the driving cab, doors, and the upper part of seats. Generally, as the waterproof performance improves, the dustproof performance will also improve accordingly.