During the past decades, consumers and car manufacturers have become more and more strict about the appearance of heat exchangers. Therefore, in the past, high-concentration flux suspension spraying brazing was used in CAB process. The flux is gradually being replaced by the lowest concentration of flux.
A low flux concentration means a reduction in the amount of flux applied under the same conditions. This makes the viscosity, rheology and other issues of the flux suspension in the production process that need not be concerned before exposed. The inherent risk of leakage of the brazed finished product brought by the design and processing accuracy of the heat exchanger components is greatly increased under the low-concentration flux process, which has caused the cost of re-brazing and even scrapping of the manufacturer to rise significantly.
In order to solve this problem, a solution idea is to spray the normal flux / pipe part with the lowest concentration of flux with a certain viscosity and rheological properties. In the pipe and head plate joints, a higher concentration of painting flux is used for a second spray or brushing.
Of course, another idea is to use the flux atomizing spray device developed by us. It can not only ensure the uniform spraying of the smallest amount of flux, but also reduce the amount of flux spraying and over spraying by more than 80%. The second solution is described in another product of our company.
The small amount of additional painting flux that is applied a second time during the brazing process, in the molten state, helps fill the joint with the brazing near the joint, thereby greatly reducing the leakage or ensuring a normal service life. . In other words, painting fluxes are of great benefit for improving leak-related qualification rates and life.
On the other hand, additional painting flux may cause some flux residues on the surface of the heat exchanger (although non-corrosive flux residues will not affect the product's life and even have some protective effects) , but it does have some impact on product aesthetics.
For most non-joint areas, because there is no risk of leakage, the additional application of flux to affect the appearance of the product is redundant or even worth the loss. Therefore, paint fluxes are usually applied by local (joint area) spraying and brushing.
In other cases, because the heat exchanger components are too large, it is not suitable for conventional flux spraying through conveyor belts. Therefore, the manufacturer may considers directly or manually spraying flux to the heat exchanger through painting flux.
Considering these usage characteristics, paint fluxes usually include flux, water, surfactant, binder, thickener and even rheological additives. All auxiliaries will decompose during the temperature rising to 200-300 ℃.
