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AC/OX CUTTING/WELDING/BRAZING Soldering and Brazing Techniques Soldering and brazing are thermal fusion processes for joining metals. The processes are related to welding, but whereas both filler material and workpiece surfaces are melted in welding, only the filler material is melted in soldering and brazing processes.

The filler material will always have a lower melting temperature than the material to be joined.

When heated, it will reach melting temperature range, liquefy and with the help of the flux spread out and bind to the surfaces of the workpieces. This bond is a result of the filler material’s ability to “wet” the workpiece. In this process there is a very faint alloying zone between the melted filler material and the base material. When the filler solidifies it will stick firmly to the base material.

Fluxes

In brazing and soldering processes it is most often required to use a flux suited for the filler material and base material. Fluxes serve three basic functions that are required to obtain a successful result.

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of the liquified alloy so that it can spread uniformly, ensuring good wetting of the base material. The dissolving ability of the fluxes is limited and they cannot be heated for any period of time. The soldering/ brazing time should, therefore not exceed 3 - 5 minutes. Overheating may also destroy the properties of the flux.

Surplus flux remaining on the workpiece after brazing should be removed by rinsing in clean water and brushing.

Keep in mind that most fluxes have a toxic content. This applies not only to Unitor’s fluxes, but to all types. Make sure that there is proper ventilation whenever you braze or solder and avoid contact with eyes, mucous membranes, skin and open wounds. Advantages of brazing and soldering 1. A quick and cheap method of joining materials which does not involve expensive equipment. 2. Most metals and combinations of metals can be joined by brazing and soldering.

1. Flux eliminates the oxide layer on the surface of the base material during the heating process, and protects against further oxidation.

3. If the correct filler metal and flux is chosen, brazing produces a bond of hight tensile strength with good corrosion resistance.

2. The flux is adapted to the filler material in such a way that it melts slightly before correct working temperature is reached, thereby indicating when filler material should be applied.

4. Due to the relatively low temperatures applied, there is little deformation and change of structure in the workpiece.

3. When the filler material is applied the flux reduces the surface tension