and brazing are terms often used to denote the same
operation that of joining similar or dissimilar metals by
means of molten metal which may be of the same kind, but
which usually has a lower melting point than the metals to
be joined. The term '"brazing" is usually employed to denote
the soldering with an alloy of copper or zinc.
is usually taken to represent the joining of surfaces by
means of an alloy of lead and tin, and "hard-soldering" is
understood to mean the process of uniting as above described
with silver and its alloys used as a uniting metal. Hard
soldering and brazing are practically the same, and are both
done in about the same way.
of brazing is the melting of a low fusing metal against the
metals to be united while they are in such a condition of
cleanliness and temperature that the metal welds itself to
Soft brass, when melted, will weld itself to iron,
copper, and a number of other metals, while the temperature
of the metals in question is at a considerable number of
degrees below their several melting points.
In fact, only
heat enough need by employed to fairly melt the uniting
metal and to render it fluid enough to flow, or to "run," as
the mechanic aptly states it.
To braze, also to solder, it is absolutely necessary that
the surfaces to be united are clean and free from oxide.
The term "clean"
is used in brazing and soldering, to mean that there is no
"matter in the wrong place" as far as the surfaces to be
operated upon are concerned. If the surfaces should be
covered with a mixture of plumbago and soap, it is pretty
sure that the brass would not adhere, and they could be
If, on the contrary, the surfaces were
daubed with grease, resin, lime, borax or similar
substances, the brazing will not be interfered with; hence,
it is better to say that surfaces to be brazed or soldered,
should be made bright and free from oxide, finger marks, and
all other matter except the proper flux to prevent
oxidization of the surfaces when heated.
This and this
alone, is the purpose of all the fluxes used either in
soldering, brazing or welding. The flux prevents oxidization
from contact of the hot metal with the air, or with the
gases from the fuel used in heating.