Spot welding means joining two or more metals parts together with the help of heat and pressure.

1. What is Resistance Spot Welding?
Spot welding
means joining two or
more metals parts
together with the
help of heat and
pressure. It is
considered one of the
oldest welding
processes. This type
of welding can be
used to weld thin or
thick foils but cannot
be used for above
about 6 mm
thickness. High
quality welds can also be made in stainless steels, nickel alloys,
aluminum alloys and titanium.
Resistance spot welding produces little fumes and very less arc
rays. Danger of flying sparks is less when compared to other
processes. But tongs and linkages can cause higher risk of mechanical
hazards such as pinching and crushing the fingers and hands.
Resistance is the opposition that a
substance offers to the flow of electric
current. If the metal has lesser
resistance, less heat is generated
when current passes through it. The
higher the resistance of a metal, the
more heat is generated when the
same current passes through it. If you
want best results in resistance
welding you should have a detailed
understanding of the materials being
welded, careful control of the heat
and pressure at the weld point, and
consideration of numerous other
factors.

2. Benefits of Resistance Welding
• High speed welding
• Easily automated
• Suitable for high rate production
• Economical
Source:
http://everlastgenerators.com/wordpress/welders/what-is-
resistance-spot-welding/