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Information Sheets
Brazing
Brazing is a metal joining process which uses a non-ferrous filler materials with a melting point below that of the base metals being joined. The filler metal wets the base metal when molten in a manner similar to that of a solder and its base metal. The melting point temperature of the filler is generally above 425 deg. C
There is s slight diffusion of the filler metal into a hot solid base metal to a surface alloying of the base and filler metals. The molten metal flows between the close-fitting metals because of capillary forces.
Commonly used brazing filler materials include:
- aluminium - silicon;
- copper - phosphorus;
- silver;
- nickel;
- Copper and copper-zinc
In order to obtain sound joints, the surfaces around the joint must be free from dirt, oil and oxides or other foreign matter at the time of brazing. Fluxes are used mainly to prevent the formation of oxides on the base and filler materials. The also promote the flow of the filler. It should be noted that many fluxes give off noxious or toxic fume when being used and required dedicated fume extraction.
The prime advantage of the laser being used as the heat source for soldering is the the heat source can be applied in a very controlled manner with control being over the position, the size of the area being heated and the amount and duration of the applied heat. The laser also applies heat without any contact with the materials being soldered or applying any mechanical forces to those materials.