& Joining Methods
spot welding (RSW)
Resistance spot welding (RSW) is a resistance
welding process which produces coalescence
at the faying surfaces in one spot by the
heat obtained from resistance to electric
current through the work parts held together
under pressure by electrodes.
The size and shape of the individually
formed welds are limited primarily by the
size and contour of the electrodes. The
equipment for resistance spot welding can
be relatively simple and inexpensive up
through extremely large multiple spot welding
machines. The stationary single spot welding
machines are of two general types: the horn
or rocker arm type and the press type.
The horn type machines have a pivoted or
rocking upper electrode arm, which is actuated
by pneumatic power or by the operator`s
physical power. They can be used for a wide
range of work but are restricted to 50 kVA
and are used for thinner gauges. For larger
machines normally over 50 kVA, the press
type machine is used. In these machines,
the upper electrode moves in a slide. The
pressure and motion are provided on the
upper electrode by hydraulic or pneumatic
pressure, or are motor operated.
For high-volume production work, such as
in the automotive industry, multiple spot
welding machines are used. These are in
the form of a press on which individual
guns carrying electrode tips are mounted.
Welds are made in a sequential order so
that all electrodes are not carrying current
at the same time.