Page 136 - CITS - Welder - Trade Practical

WELDER - CITS

Skill Sequence

Arc gouging on MS plate 10mm thick in flat position

Objectives: At the end of this exercise you shall be able to
• prepare and do the arc gouging on MS plate 10mm thick in flat position.

Prepare the pieces: Mark and cut the pieces as per given sizes by gas cutting. Clean the surfaces. Mark and

punch a straight line.
Position the plate down hand or flat.
Select the electrode and set the current.
Select a 4 mm dia. gouging electrode for a 10 mm thick plate.
Set 300 amps current in AC or DC m/c and if DC is used set the (straight polarity) electrode negative (DCEN).
Gouging the plate: Point the electrode towards one end of the edge with an angle of 20°-30° and 90° to the rear
surface of the plate. (Fig 1)

Fig 1

Strike the arc.
Note : Wear a respirator while gouging.
As the molten pool is established, lower the electrode holder and reduce the angle between 5°-15° from 20°-30°.
Move the electrode along the line of marking from the right to the left side of the plate without side movement.

While gouging is in progress push the molten pool and slag away from the arc and the gouged groove.
Due to rapid fusion because of the arc, heat, move the electrode fast and control the gouging operation.
Note : Ensure that the angle of slope is not too steep, and avoid grooving too deeply.
Note : Use safety boots and leg guards to protect the legs.

Maintain the angle and travel of electrode constant so as to obtain a groove of uniform width and depth.
Clean the gouging surfaces.
Note : Inspect the gouging.
Check the smoothness, depth and uniformity of gouging.

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CITS : C G & M - Welder - Exercise 28