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Flame Brazing

Mar 23, 2020

Flame brazing


Flame brazing is performed by using a flame formed by combusting a vaporized product of a combustible gas or liquid fuel with oxygen or air for brazing heating. It is divided into flame brazing and flame brazing.

  This welding method is widely used and versatile, the process is relatively simple, the operation technology is easy to master, and it is easy to realize automatic operation. The initial investment of the equipment is low, the types of combustion gases are many, and the source is convenient and reliable. Completed, no shielding gas is required, usually a flux is required; a wide range of solders can be used, from low-temperature silver-based solders to high-temperature nickel and copper-based solders, and there is almost no requirement on the shape of the solder , Wire, sheet, pre-formed or paste form of solder can be used in flame brazing.


  However, because flame brazing is performed in an oxidizing environment, there are flux residues and hot scale on the surface of the joint after brazing. Moreover, the heating temperature is difficult to grasp during manual operation, so workers are required to have a high level of skill. It is also unsuitable for brazing easily oxidizable metals such as titanium and zirconium. In addition, flame brazing is a local heating process that may cause stress or deformation in the base metal.

  The advantages and disadvantages of flame brazing are outstanding. Overall, its advantages are more. If you have a good eye for discovery, then it is not difficult to find that we have used this method in the welding of small and medium pieces such as bicycles, electric frames, aluminum kettle nozzles, etc. in our lives.

  If you want to use flame brazing to weld the workpiece, please refer to the following procedure!

  Before brazing, the surface of the workpiece must be cleaned strictly. The flame is then adjusted and heated in the brazed area. When brazing, it is necessary to maintain a uniform temperature, especially the temperature on the joint surface must reach the brazing temperature uniformly. Therefore, it should be maintained at the brazing temperature for a period of time as much as possible to complete the brazing material to the joint gap Inflow and gas precipitation. In order to achieve this, the welding torch is constantly oscillated during the manual brazing process; in an automated operation, the workpiece is oscillated and rotated as it passes through the heating zone, or the flame is moved around the workpiece.


  In manual flame brazing operations, feed-in and brazing materials are usually used. In automated flame brazing operations, prefabricated brazing materials or fluxes can be used. When the solder wire is delivered to the joint by hand, the solder wire is immersed in the flux first, and then the solder is used to solder the joint to the joint. This action can be completed multiple times during the heating process of the workpiece, even during the application. After the solder, if there is a phenomenon that hinders the flow of the solder, it can also be compensated by increasing the flux, while controlling the heat to make the molten solder flow through the joint. After brazing is completed, the joint must be cooled below the solid phase line of the solder in a static state to prevent the joint from cracking.