Types of Welding
Spot Welding.
Weld current is concentrated in a small area by shape of the welding electrode.
Projection Welding.
Weld current is concentrated by one or more projections
raised in one component.
The same current and force is required for each projection, so large machines capable of delivering these are required.
Used for welding of nuts and bolts and for annular ring projections (tube to sheet).
Seam Welding.
Current is concentrated by use of a narrow wheel which rotates, driving the components through the weld heads.
The welds can be overlapped, producing a gas-tight join.
Duty cycle is very high, so large transformers are necessary.
