Page 64 - CITS - Welder - Trade Theory

WELDER - CITS

5 Lack of Fusion: A condition in which fusion is less than complete.
Lack of fusion, also called cold lapping or cold shuts, occurs when there is no fusion between the weld metal and
the surfaces of the base plate.
Causes
1 Poor welding technique.
2 Use of a very wide weld joint.

3 Very low travel speed and attempting to make too large a weld in a single pass.
4 Low welding voltage.
5 Presence of Oxide layer.

6 Lack of Penetration:- A condition in which joint penetration is less than that specified.
Incomplete penetration
This type of defect is found in any of three ways:
1 When the weld bead does not penetrate the entire thickness of the base plate.

2 When two opposing weld beads do not interpenetrate.
3 When the weld bead does not penetrate the toe of a fillet weld but only bridges across it.
Welding current has the greatest effect on penetration. Incomplete penetration is usually caused by the use of
too low a welding current and can be eliminated by simply increasing the amperage. Other causes can be the
use of too slow a travel speed and an incorrect torch angle. Both will allow the molten weld metal to roll in front of
the arc, acting as a cushion to prevent penetration. The arc must be kept on the leading edge of the weld puddle.

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CITS : C G & M - Welder - Lesson 12&13 CITS : C G & M - Welder - Lesson 12&13