Terminal crimping common bad and solutions, the following automotive wiring harness processing plant Xiaobian for everyone to introduce

Crimping problems can reduce product reliability, but they can be easily avoided with a little knowledge and advance planning.

The terminal has three main parts: matching part, transition part and crimping part.

The matching part is the part where the terminal is inserted into the other half of the connecting terminal. This part is connected by a connector or terminal to the docking terminal and works in a certain way. If the matching part is deformed during crimping, the performance of the connector will be reduced.

The transition section is also designed to be unaffected during the crimping process. If you change the position of the elastic piece or terminal stop, the performance of the connector will also be affected.

The crimping part is the part of the design that is affected by the crimping process. Clamp the crimp area to securely connect to the cable using the connector manufacturer's recommended termination device. Ideally, all work of the terminal crimping on the cable occurs only in the crimping zone.

Properly executed crimping: The insulation crimping area compresses the insulation layer but does not puncture. The distance between the wire core (or wire brush) and the front of the conductor crimping area is at least equal to the diameter of the cable conductor. The insulation layer and the conductor can be seen in the section between the insulation and the conductor crimping area. The conductor crimp zone is flared at the lead-in and tail ends, while the transition zone and the bonding zone remain unchanged before and after the crimp process.

If the crimped terminal looks different from the pre-crimped terminal except for the crimped part, it may be because there was an error in the crimping process. Here are 13 of the most common problems that can occur in the crimping process, along with corrective actions.

1. The conductor crimping height is too small

Crimp height is the cross section height of the guide body crimp area after crimp, which is the most important feature of good crimp.

If the crimp height is too small or too large, the cable terminal crimp strength cannot be maintained, and the cable drawing force and rated current are reduced. In general, the performance of the crimp joint deteriorates under abnormal working conditions. Too small a crimp height can also crush the core or break the metal in the crimp area of the conductor.

2. Conductor crimping height is too high

Too large a crimp height cannot properly compress the core, causing a large void in the crimp area because there is not enough metal-to-metal contact between the core and the terminal metal.

The solution to problems 1 & 2 is simple: Adjust the height of the conductor on the crimp machine. When working with the crimp machine for the first time, use a vernier caliper or micrometer to check that the crimp height is within the specified range, and should be rechecked in accordance with the required frequency during the working process to maintain the correct crimp height.

3.&4. If the insulation crimping area is too small or too large, the insulation crimping area provides stress relief for the conductor crimping area, so that the cable core will not be broken when the cable is bent. Too small insulation crimping zone will cause excessive stress in the metal in the insulation crimping zone and weaken its stress release function.

Most types of crimping tools allow the insulation crimping height to be adjusted independently of the conductor crimping height. The proper adjustment allows the terminal to clamp the insulation at least 180 degrees and does not puncture the insulation. When the outer diameter of the insulated crimping part of the terminal is close to the outer diameter of the insulation layer of the cable, the best method is IDT technology.

5. Loose core

Loose core is another common problem that causes crimping problems. If all cores are not completely enclosed in the conductor crimping zone, the strength and current load capacity of the crimping part will be greatly reduced. To obtain a good crimp, the specified crimp height must be met. If not all cores play a role in the height and strength of the crimp, the performance of the crimp will not meet the specified requirements. In general, the problem of loose core is easily solved by reassembling the cable into a bundle and inserting it into the crimped terminal. If stripping the insulation from the cable is a separate operation, the core may be accidentally separated during handling or bunching. Using a half-strip and keeping the insulation removed, so that the insulation jacket is not completely removed from the cable until the cable is ready to be crimped with the terminal, helps minimize core loose problems.

6. The cable length is too short

If the strip length is too short, or the cable is not fully inserted into the conductor crimp area, the termination may not reach the specified pull force because the metal-to-metal contact between the cable and the terminal is reduced. The strip length of the cable is too short (the insulation layer is in the correct position), and the outer diameter of the cable cannot be obtained from the front of the conductor crimping area. The solution is simple: increase the strip length of the stripping device to the specified value of the terminal.

7. The cable is inserted too deeply

Another crimping problem associated with excessively short strip lengths occurs when the cable is inserted too deep into the crimping zone. The insulation layer is inserted too deep forward into the insulation crimping zone, and the conductor extends to the transition zone. In practice, this can cause three failure modes. Two of them are due to the reduction of metal-to-metal contact in the conductor crimping area, which reduces the rated current and cable drawing force. Metal-to-plastic contact is not as strong as metal-to-metal contact, and it does not conduct electricity.

A third failure mode may occur when the connector is engaged. If the cable extends too far into the transition zone, the tip of the pin terminal collides with the cable, which may prevent the connector from fully positioning, or may cause the pin or jack terminal to bend.

In extreme cases, terminals can be pushed out of the back of the housing even if they are fully in place inside the housing. To solve this problem, make sure that you are not using too much force to push the cable into the crimp machine beyond the cable stop of the crimp machine, or adjust the cable stop position to properly position the peeled cable axially.

8. "Banana" (over-bent) terminals

One of the most graphic crimp problems is called "banana" crimp because the crimp terminal is shaped like a banana. This makes it difficult to insert the terminal into the housing and may cause the terminal to collide. This problem can be easily solved by adjusting the position of the limit pin on the crimping machine. This small pin is located in the crimping machine and touches the junction area of the terminal when crimping the cable in the crimping area. During crimping, a large amount of metal at one end of the terminal moves (in the crimping zone). Such a large force tends to force the front of the terminal up unless restrained by an appropriate "limiting pin".

9. Crimp too far forward

A more obvious crimping problem is that the transition area is partially damaged, and the vertical protruding part is a design feature called the "terminal stop". Its function is to prevent the terminal from being inserted too deeply into the housing. If the stop is completely destroyed, the actual terminal will be pushed all the way through the housing.

The solution is simple. The problem is caused by the incorrect position of the terminal and the metal strip (the metal strip to which the terminal is attached when you receive the goods from the manufacturer) in relation to the crimp machine. Simply relax the substrate of the interchangeable tool and then realign the crimp machine to solve the problem.

10. The flare is too small

The correct size of the horn is close to 2 times the thickness of the terminal material. In essence affects the performance of the terminal, if the lack of horn, or less than the thickness of the terminal material, there is a risk of cutting the core. The reduction of retained core reduces the end connection strength. To correct the problem, make sure the punch and base on the crimp device are properly aligned.

11. Excessive flares

It can also be problematic if the horn is too large because it reduces the total area of contact between the terminal crimp area and the cable. The smaller the contact surface between the cable and the terminal, the smaller the cable pulling force. If the crimp height is correct, it may be a problem caused by tool wear and should be replaced.

12. Too long tail material

During the crimping process, the tail material is cut off from the terminal. Problems can arise if the end material is kept too long. When the terminal is inserted into the housing, an excessively long metal tail can extend to the rear of the connector, causing arcing between adjacent contacts of the connector when a high voltage is applied. If the tail material at the front of the terminal is too long, it will interfere with the connector engagement and cause "terminal collision".

The solution is simple. Adjust the feed plate on the crimp machine so that the terminal is properly centered in the crimp machine. Another sign that the terminals are not properly centered is that the horn is not properly formed. This occurs because the horn has a spatial relationship with the tool of the tail material.

13. The barb is bent

Although barb bending is not necessarily the result of an incorrect crimping process, the connector can still fail. The barb may bend inwards or outwards excessively, which affects the ability of the terminal to lock fully into the plastic housing. Barb damage may be caused by the friction wheel on the shaft holder of the crimp machine being too tight when the terminal is unrolled from the reel, or by the handling of the terminal after crimping the cable. Usually terminated cables are bundled and stored or shipped to another location in the plant. The barbs may also bend during bundling, or when each terminated cable is removed from the harness.