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A top electrode placement can work if the wire diameter is small compared to the energy setting.
In this case there is enough plasma pressure to force the molten wire onto the base material.
Placement of the electrode directly on top
of the fill wire can melt the wire into the
base if the energy is sufficient, or the wire
is very small. Alternatively, it may only melt
the wire causing it to ball as shown here.
A final scenario can occur when the electrode is placed on top of a large wire being welded to a
base material at a high weld energy setting . In this case the plasma can push the wire metal down
to the base metal surface but there may be no penetration into the base material .
HANDS ON: Try adding fill wire using the top placement method . Build up a small mound of
material .
As a rule of thumb it is always best to use the side electrode placement . This is especially true of
larger fill wire diameters . If it is essential for a top placement weld the process will be improved
by using very fine laser wire to ensure full wire melting . Choosing the correct wire gauge for your
application is very important . For example, micro-scale applications, it is important to select
the smallest fill wire available . If a wire is selected that is similar in size to the base metal, there
is a good chance that the energy setting required to melt the wire will also melt the base metal .
Alternatively, if the wire is small relative to the base metal, the wire can be melted adding material
to the base metal without any damage or warping to the base metal . For larger features, select
a wire size that will allow you to perform your task efficiently . For example, filling a large pore
should not be done with ultra-fine wire, but instead with wire of approximately the same diameter
as the pore . In this case the repair can be accomplished in literally one weld . In comparison, with
the ultra-fine wire, the repair would take many welds .
Pulse Arc Welding: Pushing Metal
There are two competing forces at work during the pulse arc welding process . The first is the
surface tension of the molten metal . Surface tension is a force between the metal atoms that is
pulling the molten pool of metal flat during the metal’s liquid phase . The Second is the electrons
from the plasma pushing the molten metal in the direction the electrode tip points . The plasma
