Flash welding is used to make an end-to-end joint of two thick metal pieces as shown in Figure 20.45. In this method, current is switched on and then the ends to be welded are brought closer slowly to make contact. Thus, heat is localized at the ends and reaches at the welding temperature. The ends, after they have contact with each other are then forced against each other by applying mechanical pressure which forces the molten metal and slag to be squeezed out in the form of sparks enabling the pure metal to form the joint and disallowing the heat to spread back.
Figure 20.45 Flash Welding
Advantages
- It consumes less current.
- Large area (end to end) can be welded.
- Edge preparation is not required.
- Excellent weld can be made at high production rate.
- The joint is stronger.
Disadvantages
- Metals like lead, zinc, tin, copper, and their alloys are not welded by this method.
- The equipment is expensive.
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