Web Search: Goods Information

Tel: 0086-571-88779191
E-mail: sales@cn-huaguang.com
Fax: 0086-571-88778459
HTTP: www.cn-huaguang.com
Brazing Knowledge

Seven Steps for a Successful Brazing

Date:2013-08-26 14:22


An optimum designing is significant for obtaining a robust joint. The overlapping length is usually four times the thickness of the matrix in the thinnest area. It is easy to be achieved for the lap joint. For other joints, the scarfing joint is another good choice. However, the gap of joint should be considered seriously in above two kinds of joint since the brazed workpieces are joined through capillary effect and the capillary effect was determined by the joint gap. For Cu-P and Ag based brazing alloy, the ideal joint gap should reach 0.001-0.005 inch. For joining dissimilar materials, the thermal expansion rate of each kind of metal in different temperatures should also be considered in designing the joint gap.

Cleaning before Brazing

The capillary effect can be exerted to the largest extent in brazing workpieces with clean surface. For the workpieces with greasy dirt surface, the organic solvent should be introduced to clean the surface. For the surface with severe oxides, the sandblasting way is always used to clean the surface.


For clean workpieces, we should pay more attention to protect the surface being oxidizing during brazing since the surface without any protection will be oxidized easily to prevent effective capillary effect due to the flame. The proper flux or protective atmosphere can protect the workpieces or brazing alloy being oxidizing. When Cu-P brazing alloys are introducing into joining copper and copper, the extra flux can not be used since the phosphorus element in the Cu-P brazing alloy can act as the deoxidizer.

Assembling and Clamping

It is significant to align the brazing workpieces in a proper position, which could make the capillary effect exert to the largest extent. Usually, the weight of workpieces can make the assembly contact closely. When the workpieces need to be clamped, the jigs should be small and show the ability of lower heat conductivity in order to decrease heat loss during brazing.

Choosing brazing alloy

The compatibility of the joined materials should be considered firstly in choosing the brazing alloy. Besides, other factors should not be neglected, such as the joint gap, brazing temperature, heating ways, working temperature and environment factors and so on.


There are many heating ways in brazing and the flame brazing is the most common one. Firstly, the whole assemblies need to be heated to the brazing temperature. Secondly, the brazing alloy was applied on the substrates once reaching the brazing temperature. Lastly, the molten brazing alloy filled the joint gap due to capillary effect and completed the joining.

Cleaning after brazing

The joints should be cooled naturally. Due to corrosion of the flux, any flux residue residing in the joint could weaken the joint. The flux residue could be cleared by immersing the joint in the hot water. If the flux began to etch and the residue may occur, the pickling method should be introduced into remove residue.

TypeInfo: Brazing Knowledge

Keywords for the information: