1. Structure of the terminal.
The structure of the terminal has the terminal head, barb, front foot, flare, back foot and clipped tail.
And can be divided into 3 areas: crimp area, transition area, joint area.
Please see the following figure:
Let's take a look at them.
Terminal head: generally inserted with the rubber shell of the female head
Barb: Prevent falling off when inserted with the parent rubber shell
Front foot: It is an important part of the wire and the terminal
Horn: prevent the terminal from being cut and protect the conductor (copper wire)
Rear foot: Prevent the part between the conductor and the terminal from breaking due to shaking during the shaking of the wire
Tail clipping: the product of the connection between the terminal and the material belt, has no practical effect.
Crimp area: The conductor rivet process needs to be in this area.
2. Common adverse conditions of terminal deformation.
In the process of transportation, handling, and use, if the terminal does not reach a certain shape specification, then no matter what is inserted and connected, it is not effective.
3. Defective products
(1).Example
| Item | Reference Pictures | Cause Season |
| Partial of wire is not crimped into wire barrel. |  |
a. careless operationb.the exposed wire is flaring after stripping |
| Extruded wire at wire barrel is too long. |  |
a. stripp length too long/too shortb. incorrect wire setting
c. wire shink |
| Extruded wire at wire barrel is not long enough. |  |
|
| Terminal bent upward. |  |
a. crimping height too lowb. incorrectly adjusted tooling
c. there are scraps sticked on the blade |
| Terminal bent downward |  |
(2)Deep punching (coated)
The rubber of the wire is wrapped into the horn mouth, even beyond the range of the horn to the front foot, which is easy to cause insufficient tension, resulting in short circuit.
(See the picture below for details)
(3) Crimped less (less plastic)
Less plastic crimped is the opposite of the adhesive, the rubber of the wire does not reach the crimping range of the front foot, which is easy to cause a force to be pulled out, resulting in insufficient tension and terminal fall off. (See the picture below for details)
(4) Conductor too long (copper wire too long)
It is mainly caused by the peeling process that some conductors are too long or too short, and even bifurcation. What are the consequences of this? According to the test, this is easy to cause short circuit, voltage resistance and insulation and other poor.
(5）Terminal oxidation.
Here we also need to note that the basic majority of the terminals are made of electrolytic copper as the base. Copper has excellent metalworking properties and high corrosion resistance, and electrical conductivity is very good, only second to silver. However, the terminals are easily oxidized when they are exposed to water during production and production in a humid environment for a long time.
4. There are three common failure forms of wiring terminals:
(1) Poor contact.
The metal conductor inside the terminal is the core part of the terminal, which transfers the voltage, current or signal from the external wire or cable to the corresponding contact with its matching connector. Therefore, the contact parts must have excellent structure, stable and reliable contact retention force and good electrical conductivity. Due to the unreasonable structural design of the contact parts, the wrong selection of materials, the instability of the mold, the abnormal processing size, the rough surface, the unreasonable surface treatment process such as heat treatment and electroplating, the improper assembly, the poor storage and use environment and the improper operation and use will cause poor contact in the contact parts and the matching parts.
(2) Poor insulation.
The function of the insulator is to keep the contacts in the correct position, and to insulate each other between the contacts and the contacts, and between the contacts and the shell. Therefore, the insulation parts must have excellent electrical properties, mechanical properties and process forming properties. Especially with the widespread use of high-density, miniaturized terminal blocks, the effective wall thickness of insulators is getting thinner and thinner. This puts more stringent requirements on insulation materials, injection mold accuracy and molding processes. Due to the existence of metal residues on the surface or inside the insulator, surface dust, flux and other pollution by moisture, organic material precipitates and harmful gas adsorption film and surface water film fusion to form ionic conductive channels, moisture absorption, mildew, insulation material aging and other reasons, will cause short circuit, leakage, breakdown, low insulation resistance poor insulation phenomenon.
(3) Improper fixation.
Insulators not only act as insulation, but also usually provide precise neutralization protection for extended contacts, but also have the function of installation positioning, locking and fixing to the equipment. Poor fixation, light impact contact reliable cause instant power failure, serious is the disintegration of the product. Disintegration refers to the abnormal separation between the plug and socket and between the pin and the jack caused by the unreliable structure of the terminal in the plugging state due to the material, design, process and other reasons, which will cause the serious consequences of the interruption of the power transmission and signal control of the control system. Due to unreliable design, wrong material selection, improper selection of forming process, poor process quality of heat treatment, mold, assembly, welding, assembly is not in place, etc., will cause poor fixing.
In addition, due to coating peeling, corrosion, bruises, plastic shell flaring, cracking, rough processing of contact parts, deformation and other reasons caused by poor appearance, due to positioning lock size is poor, poor processing quality consistency, total separation force is too large and other reasons caused by poor interchange, is also a common disease. These faults can generally be found and eliminated in time during inspection and use.
Post time: Dec-04-2023