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Soldering
and brazing are very much alike, resulting in the names of
the joints being confused and interchanged. The definitions
are different only in a technical and arbitrary way. Actually,
it is desirable to separate the two processes to some degree.
The American Welding Society has selected an arbitrary temperature
of 800° F as a line of demarkation between the two processes.
The definitions of each process follow:
Soldering A joining process wherein a joint is produced
by heating, generally below 800°F and using a nonferrous
filler metal that has a melting point below that of the base
metals. The filler metal is distributed between the properly
fitted parts by capillary attraction.
Brazing A joining process that is identical to soldering
except that the joining takes place at temperatures above
800éF. The filler metal is distributed between closely fitted
surfaces of the joint by capillary attraction.
What many mechanics call brazing is really braze-welding,
wherein, a nonferrous filler metal is
applied but is not distributed to the joint by capillary action.
Since brazing alloys are much stronger than solder alloys,
the brazed joint does not require as much depth to achieve
the strength as does the soldered joint. To achieve that strength,
the filler metal must alloy with the base metal. For the filler
metal to properly combine with the base metal, the soldering
or brazing condition must be good. There are eight basic steps
in making capillary metallurgical joints. The eight operations
listed here in order in which they are performed; not in the
order of importance.
- Cutting
and sizing the parts to be joined.
- Cleaning.
- Fluxing.
- Assembling
and supporting or jigging.
- Heating.
- Applying
filler metal.
- Cooling.
- Post-cleaning.
Sometimes there are several added operations for cooling
and post-cleaning. These steps may be required for many
operations in order to prevent further action by the flux.
Soldering and brazing are both widely used processes for
many maintenance and repair applications. When the basic
procedures are followed and the correct filler alloys are
used, successful joints result.
Brazing is a joining process wherein a joint is produced
using a filler metal and by heating at
temperatures above 800°F.
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