Mig spot welding is a process which uses a timed Mig arc to join two
thicknesses of metal by
penetrating through one into the other one to form a cast weld nugget.
It may be used where
resistance spot welding is inaccessible or would not be practical.
Applications of this process in
the automotive, truck cab and related industries may take advantage of
a number of benefits it
offers, as follows:
a. Welds can be made in joints where there is accessibility to only
b. The weld need not necessarily mark the reverse side of the joint.
c. Special metal preparation is not necessary so long as the surface
is free from contaminants.
d. Operator skill is minimal.
e. The welding machines are less expensive than resistance spot
f. The welding gun can be portable and there is no "throat depth"
limitation as with resistance
Some process limitations must also be considered.
a. On material greater than 1/16-inch thick the process is only
practical in the flat position.
b. The two thicknesses of material must be in tight contact to insure
correct thermal distribution
c. Welds cannot be made through adhesives or sealants.
d. Quality and strength of welds is dependent on consistent
performance of the wire feed system.
Thus, regular checking and maintenance of the equipment is essential.