29
OrionWelders.com
ch
.
4
temperature (especially at the interface between the two pieces) can become hot enough to melt
the metal in a spot . The terms resistance welder and spot welder are descriptive of this process .
If you limit the amount of energy and electrical current going into the weld you can create a
temporary or weak weld called a “tack” weld . It provides the ability to temporarily position a part
before permanent welding . This ability opens a multitude of creative possibilities . It also helps
eliminate the need for complicated binding or clamping of parts before permanent welding or
soldering .
Because the heart of the Orion is an industrial capacitive resistance welder, everything from one
time custom pieces to production welding is possible .
Left:
A typical (industrial) welding
configuration . Right: A close-up
zoom of the weld showing the
electrical resistances that are
used to create the weld spot .
As shown in the figure above, a typical weld configuration requires a positive and negative
electrode with pressure applied to the work piece parts . As we zoom in on a cross sectional
view of the work piece parts, we can identify the electrical resistance locations where heat is
generated . For fine spot, or small scale resistance welding, most of the heat is generated at the
contact point between the two work pieces . This has been identified on the figure as the largest
resistance point . During the weld a large pulse of electrical current is dumped quickly through the
work piece causing rapid heating and melting at the electrode location .
Left:
On the micro scale all surfaces have a degree of surface roughness. This roughness causes
the work pieces to only contact in a limited number of locations. Middle: Applying more pressure
will cause more surface contact, less resistance and less resistive heating. Right: Applying less
pressure will cause less surface contact, more resistance for better resistive heating.
A resistance welder uses the resistance to the flow of electricity
to heat and melt the part via a large electrical current . This contact
point is where the highest heat is generated . Light pressure
between the parts means less contact between the two surfaces,
more resistance, and hence more heating and melting . Heavy
pressure between the parts translates to more contact between
the two surfaces, less resistance, and less heating .