Seam welding is the one type of resistance welding and also another modification
of spot welding. The basic chief difference of spot weld and seam weld is that the
formation of electrode. They are usually power driven and rotate whilst gripping
the work. The current is supplied through the rotatable wheel and melt the metal.
The edges of the two sheets must be overlap, so that the welding heat can be developed
in joining interface of the sheet metal. The large manufacturing of cylindrical container,
drum, pipe, etc. is best suited by these types of welding.
When the body is being performed into a
tube, the overlapping edge made in united piece which is called longitudinal welding
and the end position fitted of assembly work welding is called circumferential welding.
The use of seam welding is mainly designated for the thin sheet metal, the sheet
metal often welded which should not exceed 1/8 inch. The welding speed may vary with
the sheet gauge. The special machines are employed for the faster welding speed.
In the bellow diagram shown the basic principle of seam welding.
Principle of seam welding diagram
Generally two types of seam welding machines found 1) Circumferential Seam Welding
Machine 2) Longitudinal Seam Welding Machine. They are called because of the types
of welding joint performance. Although the Universal Seam Welding Machine can perform
both operation. By the changing of electrode assembly the circumferential welding
can be converted into longitudinal welding.
In the seam welding operation, the sheets to be welded are properly overlapped and
positioned between the both rollers. The clamp may be provided for the holding properly
and applying the pressure. A current is provided through rollers to the material
contact with them. The sufficient heat is produced and material reached in plastic
stage. The welding operation done by pressure applied with both rollers and applied
The another important factor with roller cooling efficient. The huge amount of heat
is developed through the rollers, so its required sufficient cooling system, which
is increase the life of roller electrodes. The removal of heat from region of the
work the special type roller is used. Which is cooling system is provided. After
a short period of use the edges of the electrodes require trimming, the trimming
operating can not be obtained by filling operation. The trimming or re-shaping operation
of copper alloy electrode properly done with lath machining. The another process
to reshaping the electrode fit into the roller machine, which have plus point is
no material loss happened. The self trimming device is widely used which is which
keeps the edge of electrode constantly good condition.