Metal Arc Welding and Its Process

In the metal-arc welding a metal rod is used as one electrode, while the work being welded is used as another electrode. The temperature produced is about 2400*C and 2600*C on the negative and positive electrode respectively. During the welding operation, this metal electrode is melted by the heat of the arc, and is fused with the base metal, thus forming a solid union after the metal has been cooled. Both ac and dc may be used.

The welding operation is started by adjusting the machine to the correct amperage which is determined by the size of the rod to be used. The correct welding speed is important. Various currents can have a deciding effect on the forming of proper beads. A welding shows bead characteristics under different conditions:

1. Welding current too low-excessive piling of the metal.

2. Welding current too high - causing excessive splatter.

3. Voltage too high - bead too small.

4. Welding speed too slow - cause excessive piling up of weld metal.

5. Proper current and timing - create a smooth, regular, well-formed bead.

Under cutting is also result o too much current. No enough current results in overlapping and a lack of fusion with the metal.

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