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Types and structures of automobile harness terminals
Time:2021-09-24 Read: 1368

1、 Definition of terminal

Male terminal (male terminal)=terminal that is usually matched with male connector.

Female terminal (female terminal)=terminal that usually matches the female connector.

2、 Terminal size

That is, the width of the male terminal when the male terminal and the female terminal match.

3、 Common mechanical properties of terminals

Vertical force; The force exerted vertically on the male terminal by the female terminal [usually in g].

Insertion force; The force applied when inserting the terminal.

Terminal overlap (engagement length) Terminal overlap or engagement length. USCAR design requires at least 1 mm.

4、 Wire diameter of terminal matching

Wire diameter is the cross-sectional area of the conductor in the wire

Take a chestnut:

The cross-sectional area of terminals with size 2.8 is:

2.8mm (terminal width) x 0.8mm (terminal width)=2.24mm ²

Applicable wire conductor size is 2.5mm ² (approximate value), its terminal current carrying capacity is 20A.

It is important that the size of the wire match the terminal system used.

5、 Terminal polarization

The terminal is equipped with a polarization bar. If the terminal is inserted into the connector in the wrong direction, the polarization bar will prevent the terminal from being inserted.

The right direction

Only terminals with the correct orientation can be inserted into the hole of the connector.

Wrong direction

Terminals with the wrong direction cannot be inserted into the hole of the connector.

6、 Terminal sealing form

6.1 Gasket sealing


It can meet the requirements of small spacing/density assembly

The terminal only needs to press the wire


When matching the sealing plug, the diameter of the insulation layer must be carefully handled

The unused hole position is mainly blocked to maintain the sealing effect

The general connector needs a cover to ensure the DF load of the wire

6.2 Single-line sealing


Unused hole positions are easily blocked (usually using plugs or gamblers)

The size of wires can be easily changed


It is difficult to crimp the sealing plug onto the terminal

The part number and size of the sealing plug must match the size of the wire

Plug-in terminals may be troublesome

7、 Terminal type

7.1 Non-waterproof terminal

7.1.1 Metal shrapnel

The terminal is usually locked by metal spring, which is generally designed as one-piece or two-piece

The locking lug on the terminal body is generally better than this type of terminal used in Europe

7.1.2 No metal shrapnel

The locking mechanism is in the connector, and the terminal is usually one-piece design

7.2 Waterproof terminal

7.2.1 No metal shrapnel (sealed with gasket)

Terminals with gasket connectors usually use the "clean body" type terminals. The clean body generally refers to the terminal without spring, and the terminal body has no sharp outer or edge.

7.2.2 No metal shrapnel (sealed with single-wire sealing plug)

The single-wire sealing plug is crimped on the terminal.

8、 Comparison between metal and plastic locking

Lock on shrapnel (metal shrapnel)

Advantages of metal shrapnel:

1. The retention force between terminal and connector is higher than that of primary locking

2. When the terminal is inserted into the connector, the tactile and auditory response is higher

3. The metal shrapnel is more reliable to prevent the operator from turning out the terminal with the wrong rework tool

Advantages of locking spring on connector (plastic locking)

1. The insertion force of the terminal is small

2. Connectors with gaskets can be used for terminals

9、 Potential risks

After the terminals are crimped, the general harness factory will bind the terminals together. In this case, metal shrapnel may damage adjacent terminals, sealing plugs and wires.

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