brazing techniques is a joining of metal process by heat the base metal including the temperature above 427⁰c. During the welding process add a non-ferrous filler metal is called spelter, and which is melts and flux for activate the surface. In this welding process only filler metal are melted, and not the base metal.
The filler metal drawn in to joint process by capillary action and distributed by tinning. It is some time makes hard soldering or silver soldering. Because of the filler metals is hard solder or silver based alloy. For steel used as combination of 10% of Ni, 40% of Zi, 50% Cu and melting point temperature above 900⁰c.
Brazing process as follows:
It is very similar to oxyacetylene welding process, it provide good bonding by required to cleaned by mechanical, chemical or both combination together. The work piece and filler metal are properly.
First clean the surface of metal such as mechanical cleaning, a file and use steel wool. The chemical clean surface obtained acid by use of warm water.
The work piece is mounted with support and clamped. That is important because of the finish bond become a weak, the joint move during the braze.
The braze of metal depends upon the flux used and base metal. The metal of flux is selected depends upon suitable work metal.
The weld work piece is heated under correct brazing temperature. The heating of work piece by using gas torch, the torch flame adjusts to a neutral flame because the flames give the best result under normal condition. In this method can be weld to aluminum metal but that is difficulty. The brazing agent molten temperature range from 10 to 20 degree only that lower than aluminum, it is no red- hot temperature and indicate like steel metal. As shown in figure different form of filler materials used in brazing techniques.
- Torch and rod filler material for the plate joint process.
- Ring of filler metal at the entrance of gap.
- The foil of filler metal between flat part surfaces.
some advantage as compared to welding:
The important brazing techniques advantages as compared to welding process,
- Heat distortion is very less.
- It can be welded dissimilar metals
- If used for metal with poor weldability.
- It not affects the heat treatment of original materials.
Some of industrial brazing applications:
- It is used to fastening of radiators, electrical parts, tanks, pipe fitting, axles and more.
- it can be weld to dissimilar metal, cast metal and ferrous metal.
- it is used to joint of band saws in bicycle parts such as rims and frames.