1. There are oils or other contaminants in the brazing joint, which limits the cleaning effect of the flux.
Compared with brazing materials, the flux melts at a lower temperature and penetrates into the joint. After the flux penetrates into the joint, the presence of oxides is reduced, and then the molten brazing material can be spread, wetted and filled. If there is serious contamination at the joint position, this normal brazing process will not occur. Even if the flux has penetrated into the joint, it cannot successfully remove contaminants.
2. The assembly gap of the brazing joint is too large or too small
The molten silver brazing filler metal needs to be capillary on the closely-fitting surface. The joint gap can be increased, but it is likely to bring about the disappearance of capillary action, and if the joint gap is too small, it may also eliminate capillary action. The silver solder requires sufficient joint clearance to flow. At the same time, the wrong heating method may also cause the solder to fail to melt and flow correctly.
3. Wrong use of flux
The flux must be used correctly to ensure the consistency of flux quality and the accuracy of flux dosage. At the same time, it is necessary to ensure the correctness of the position of the flux, and reasonably control the amount of flux at different positions. on the other hand. Different brazing operators have different ways of mixing flux. At the same time, due to the difference in temperature and humidity, the flux will be different in the course of a day or a season.
4. The solder ring is too loose or placed in the wrong position
The solder ring needs to be fastened to the brazing pipe fitting and maintain physical contact with the pipe fitting. The induction coil should heat the tube and fittings, and the solder ring will melt through heat conduction. If the brazing filler metal is not properly preset, due to the large gap between it and the pipe, the brazing filler metal will only stick to the top of the steel fitting after melting, and will not penetrate into the joint.
We should thoroughly check the tolerances of parts, equipment and process procedures during brazing. Discover unacceptable condition variables during brazing and avoid them completely.