What are the common faults of terminals?
The plastic insulating materials and conductive parts of the terminal are directly related to the quality of the terminal, which determine the insulation and conductivity of the terminal respectively. The failure of any terminal will lead to the failure of the whole system engineering. It is said that prevention is the purpose and analysis is the basis. It is pointed out that from a certain point of view, the function of the terminal block should be: the contact part should be connected, and the contact should be reliable. The insulation parts that should not be conductive must be insulated reliably.
There are three kinds of common fault forms of wiring terminals
1. Poor contact
The metal conductor inside the terminal is the core part of the terminal. It transmits the voltage, current or signal from the external wire or cable to the contact corresponding to the corresponding connector. Therefore, the contact must have excellent structure, stable and reliable contact retention force and good conductivity. Due to the unreasonable structural design of contact parts, wrong material selection, unstable mold, over tolerance of processing size, rough surface, unreasonable surface treatment process such as heat treatment and electroplating, improper assembly, bad storage and use environment and improper operation, poor contact will be caused at the contact parts and matching parts of the contact parts.
2. Poor insulation
The function of the insulator is to keep the contact in the correct position and to insulate the contacts and the shell from each other. Therefore, the insulating parts must have excellent electrical performance, mechanical performance and molding performance. Especially with the wide use of high density and miniaturized terminals, the effective wall thickness of insulator is becoming thinner and thinner. This puts forward more stringent requirements for insulation materials, injection mold precision and molding process. Due to the existence of metal surplus on the surface or inside of insulator, surface dust, flux pollution and moisture, organic material precipitation and harmful gas adsorption film and surface water film fusion to form ionic conductive channel, moisture absorption, mildew growth, insulation material aging and other reasons, will cause short circuit, electric leakage, breakdown, low insulation resistance and poor insulation phenomenon.
3. Poor fixation
The insulator not only plays the role of insulation, but also provides accurate neutralization protection for the extended contact, and also has the functions of installation, positioning, locking and fixing on the equipment. Poor fixation, light impact on contact reliability, resulting in instant power failure, serious is product disintegration. Disassembly refers to the abnormal separation between plug and socket and between pin and socket due to unreliable structure due to material, design, process and other reasons when the terminal is in the plug-in state, which will cause serious consequences of power transmission and signal control interruption of control system. Due to unreliable design, wrong material selection, improper selection of molding process, poor process quality of heat treatment, mold, assembly, welding, etc., and assembly is not in place, etc., it will cause poor fixation.
In addition, poor appearance caused by coating peeling, corrosion, bruise, plastic shell flash, fracture, rough processing and deformation of contact parts, and poor interchangeability caused by poor positioning and locking fit size, poor consistency of processing quality and excessive total separation force are also common diseases. These kinds of faults can be found and eliminated in time in the process of inspection and use.
Without reliable terminals, there will be no reliable system engineering. Failure and reliability are two aspects of a contradictory body corresponding and interrelated. Through the reliability screening of terminal blocks, various failure modes and failure mechanisms can be found, which can lead to a lot of experience and lessons and eliminate various hidden dangers. It can provide a scientific basis for improving the design, process, inspection and use. It is also an important basis for revising and formulating the technical conditions of terminal blocks. The ultimate goal of failure analysis is to find out the measures to prevent failure and realize the transformation from failure to reliability.