Closed Terminal Crimping Form and Application

In automotive wiring harness, the end of each wire is crimped with a terminal, and the crimping quality of the terminal and the wire plays a vital role in the overall quality of the wiring harness. At the same time, the control of the crimping quality of this part has been recognized by all wiring harness factories. Therefore, it is of great significance to conduct an in-depth study on the crimping in this area.

As we know, most of the terminals crimped at the end of the harness are open crimped terminals. For such terminals, due to the large amount of usage, each wiring harness factory has conducted in-depth research on its crimping method, and formulated specific operation instructions to control the crimping quality of these terminals.

However, with the development of automobile manufacturing technology, especially the development of hybrid and pure electric vehicles, the application of closed terminals in automotive wiring harness is more and more extensive. As for the closed terminal, it was rarely used in the previous automotive wiring harness, and now many wiring harness factories don't know how to start with the crimping technology and quality control of the terminal, so it is particularly important to systematically study the crimping forms of the closed terminal and the suitable occasions of various crimping forms. The author introduces several crimping forms of closed terminals below.

1 Diamond Crimping

This crimping method is suitable for occasions where the wall thickness of the crimping terminal is very thin and the requirement of crimping quality is not high. In order to increase the pull-out force of the wire from the terminal, in the longitudinal direction of the terminal, it is composed of a plurality of rhombus, and each rhombus is evenly distributed, and the directions of the rhombus are staggered at intervals.

Because the wall thickness of this terminal is very thin, and the crimping force is not large, the crimping can be realized by using special manual crimping pliers. Of course, there are also special crimping machines, but the relatively high investment cost makes it uneconomical to do. This crimping method is commonly used in the wiring harness of household appliances, and is used to fix the head of the wire, and then it is fixed in the line by screw extrusion. At present, this kind of crimping method is also seen in automotive wiring harness, but it is seldom used because of its low quality, and it is generally used in less important parts of automotive wiring harness.

2 Point Crimping

This crimping method is mainly suitable for hole joints and crimping barrels with relatively thick wall thickness.

Because the wall thickness of this terminal is relatively thick, and the crimping force is a bit large, it can't be achieved with manual crimping pliers, but it can be achieved with special hydraulic pliers. However, the quality of the hydraulic pliers is not high and the efficiency is extremely low. Wire harness factories generally use special dies to achieve the crimping in punch presses, so that the height of the crimping can be accurately controlled, and the crimping quality and efficiency are better than those of hydraulic pliers.

This type of terminal is mainly used in the main circuit of the automobile, which plays a role in transmitting electric power to the automobile circuit, so it requires higher quality of crimping.

3 Two-Point Crimping

This type of crimping is suitable for both the hole joint and the crimping barrel with relatively thick wall thickness, but the size of the hole joint and the crimping barrel is larger, and it is not enough to fully deform the crimped terminal by a little crimping.

This kind of crimping is very powerful, and the wire harness factory generally uses a special die on the punch to realize the crimping, thus realizing the precise control of the crimping height.

4 Four-Point Crimping

This crimping form is suitable for aviation plug pins with relatively thick wall thickness and relatively small volume. The crimping of this terminal is forced from four sides to form four pits.

This form of crimping is the best form of crimping, because the force is applied from all sides, the force is uniform, and the redundant materials of terminals have a place to go, so the force of crimping is not great. However, this form of crimping requires a complicated structure of the crimping die, so the investment cost is relatively high. At the same time, due to the complicated structure of the crimping die, it is difficult to design the crimping die for larger terminals, so this type of crimping is only suitable for the crimping of smaller terminals.

This type of crimping is mainly used in the parts of aviation plugs in automotive wiring harness, but it is not widely used in automotive wiring harness.

5 Hexagonal Crimping

This type of crimping is suitable for terminals with very thick wall thickness, and the shape of crimping is close to a regular hexagon if all the above types of crimping are insufficient to fully deform the terminals.

Because this kind of pressed material has no place to go, and the terminal should not be deformed, it is required that the matching between the terminal and the wire should be very good. If the matching is not good, some holes will be found in the cross-section analysis of the crimped terminal, which is unqualified. Sometimes, in order to make up for this problem, a point will be added on the upper and lower sides of the hexagon to enhance the compactness of crimping and increase the drawing force at the same time.

This form of crimping force is also very large, and it is also necessary to realize the crimping by a special die on the punch press, so as to realize the precise control of the crimping height. In addition, some special terminals have two holes for crimping two wires. We can also achieve this by pressing the hexagon, but the upper and lower sides are longer.

With the development of modern automobile technology, especially the application of electric drive technology in automobiles, more and more closed terminals have been widely used in automotive wiring harness. Through the research of closed terminal crimping, it is significant to fully grasp this technology and make the performance of automotive wiring harness more stable at present and in the future.