Missed welding generally refers to the solder joint without welding in the welding process. It is very simple to form a quality accident. The real cause of missing welding is difficult to find, and the entry point to solve the problem is not clear. The preventive measures can only strengthen self inspection, increase activity quality inspection and increase the frequency of final inspection to eliminate the occurrence of missing welding and open welding. Unqualified products shall not be handed over to the next process.

　　Dye penetrant can be used to detect the leakage data of electric welding. Dye detection is a non-destructive testing method. It is an appearance testing method, which is mainly used to explore the appearance damage such as cracks that cannot be recognized by the naked eye, such as the defects near the appearance of stainless steel data (cracks), pores, porosity, delamination, incomplete penetration and incomplete fusion (also known as Pt testing). It is applicable to check the dense metal data (weld), non-metallic data (glass, ceramics, fluoroplastics) and the defects of product appearance opening (cracks, pores, etc.).

　　Basic principle of dye penetrant flaw detector: paint the surface of the data with colorant, and the colorant enters the damaged part. After placing for a period of time, rinse off the colorant on the surface. Apply the developer to the cleaned surface, and the damaged part can be seen clearly because the colorant enters it.

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