The seal is a very important part of the automotive wiring harness, and its quality is directly related to the function of the wiring harness, whether it is directly used in the wire harness or the automotive connector.

More and more attention has been paid to the durability and reliability of auto parts. As a protective material, silicone rubber parts are widely used in automobiles, among which the importance of the sealing ring is self-evident, especially for the wiring harness protection of the engine compartment and the lower chassis of the automobile, because usually, these two places are more likely to be in harsh environment.

There is a concept of “wet zone” that we need to know. Generally speaking, we refer to the areas where the engine compartment and the lower body of the car are exposed to the air and often affected by rain and water as “wet zone”. Correspondingly, parts like the cockpit and trunk are unaffected by rain and this part is called the “dry zone”.

One of the biggest roles of the wiring harness seal is to isolate the wet area and the dry area. The common part is to assemble one between the engine room and the cockpit to separate the dry area and the wet area. There is also the need to assemble a seal in the left and right rear wheel ABS wiring harness, specifically under the rear seat (such as golf), there is a seal to separate the inside and outside parts, to ensure that the water at the bottom of the driving process will not leak into the cab.

The electrical appliance in the dry area is less affected by high temperature/humidity and chemicals/dust, while in the wet area, on the contrary, if the seal is poor, it may lead to the water inlet of electrical appliances and wiring harnesses, resulting in short circuit/corrosion of internal circuits, which directly leads to functional failure. Therefore, the connector of wiring harnesses should be sealed. For example, The ESP-SG plug in the engine compartment of an automobile is designed for air tightness. When you open the connector, you can see one layer of the seal with oil. The performance of the seal is directly related to the normal function.

Typically, there are two ways that connectors and other electronic components may get into the water,

• The external liquid by gravity penetration into its interior, such as connector without seal;
• Water from the wiring harness internal connection；

Here we should emphasize the word “siphon”, because general electrical appliances will work under a certain temperature, and the inner air will form pressure. When stop working, the temperature and the internal pressure drop then will form a pressure difference, if the connector seal is bad, water vapor will follow the gap between the copper wire into the interior, resulting in function failure; Therefore, connectors in wet areas are generally required to equip well-performed seals.

• Silicone Rubber Seal

It has excellent heat resistance, cold resistance, ozone resistance, and atmospheric aging resistance. It has good insulation properties. Suitable for household appliances such as electric water heaters, electric iron, microwave oven, etc. The general temperature range is -55~250 ℃.

• NBR Seal

Suitable for use in petroleum hydraulic oil, ethylene glycol hydraulic oil, diester lubricating oil, gasoline, water, silicone grease, silicone oil, and other media. The general temperature range is -40~120 ℃.

• FLS Seal

Its performance combining the advantages of fluorine rubber and silicone rubber, including oil resistance, solvent resistance, fuel oil resistance, and high and low-temperature resistance are good.

• EPDM Seal

It has good weather resistance, ozone resistance, water resistance, and chemical resistance. It can be used for alcohol and ketone, and work under high temperatures. Generally, its temperature range is -55~150 ℃.

• CR Seal

Sun-resistant is weather-resistant performance is particularly good. Suitable for all kinds of atmospheric contact, sunlight, ozone environment, and all kinds of fire resistance, and chemical corrosion resistance of the seal link. It is not recommended for use in strong acids, nitro hydrocarbons, esters, chloroform, and ketones. The general temperature range is -55~120 ℃.

• ACM Seal

Excellent resistance to oil, high-temperature resistance, and weather resistance are good, but the mechanical strength, compression deformation rate, and water resistance are slightly poor. It is generally used in the automotive transmission system and power steering system. But it is not suitable for hot water, brake oil, or phosphate ester. The general temperature range is -25~170 ℃.

• PU seal

This material has very good mechanical properties. Its wear resistance and high-pressure resistance are far better than other rubber materials. Aging resistance, ozone resistance, and oil resistance is also quite good, but it is easy to hydrolysis under high temperatures. The general temperature range is -45~90 ℃.