What Is Dip Brazing?
To braze is to join two or more pieces of metal by means of flowing a filler metal between the joint interfaces at a temperature below the melting point of the base metal but above 900°F. The filler metal, upon cooling to the solid state, forms a strong metallic bond throughout the joined area.
In aluminum dip brazing the filler metal is basically 88% aluminum and 12% silicon.
The parts to be brazed after being chemically cleaned, are assembled with the filler metal preplaced as near the joints as possible. The assembly is then preheated in an air furnace to 1,025°F to insure uniform temperature of dissimilar masses in the assembly. The part is then immersed in a molten salt bath. These salts are actually aluminum brazing flux. The bath is maintained at 1,095°F±5°F in a salt bath furnace. As the assembly is immersed or dipped, the molten flux comes in contact with all internal and external surfaces simultaneously. This liquid heat is extremely fast and uniform.
Since the bath is a flux, complete bonding on oxide-free surfaces assures unusually high quality joints. The time of immersion is determined by the mass to be heated but is seldom over two minutes in duration.
How To Design For Dip Brazing
Permanent Mold C712
Sand Cast A712