Page 38 - CITS - Welder - Trade Practical

WELDER - CITS

• Ignite and set the neutral flame.
• Allow for sufficient preheating, and then switch ‘on’ the jet of oxygen.

• Simultaneously switch ‘on’ the machine to move the cutting unit forward with the correct speed on the rails to
make a straight line cut.
• Stop the machine and turn the switch to neutral position at the end of the cut.

• Set the cutting nozzle to 30° angle and cut the bevel similar to the straight line cut.
• Turn the job plate by 180° and cut the 60° bevel angle by setting the cutting nozzle to 60°.
• Arrest the linear movement of the cutting unit of the machine with the rails using a clamp and attach it to the
pivot block used for cutting circle and profiles.
• Set the pivot block to get the required diameter and fix it on the machine table.
• Set the cutting nozzle perpendicular to the job plate and ignite it and set the preheating flame.
• When the plate becomes red hot, open the stream of cutting oxygen and cut the circle.
• For profile cutting attach the template of the profile to the machine table and make the cutting head unit to
follow the profile.
• After the cut is over stop all machine movements and remove the slag from all the gas cut surfaces.
• Use tongs while handling the gas cut job.

• Ensure that the molten slag diving cutting and solidified hot slag chipped after cutting fall into a collecting
through kept below the table.
• Clean the cutting edges from slag and inspect the cut for gas cutting defects.

Skill Sequence

Assembly of the portable cutting machine

Objectives: At the end of this exercise, you shall be able to
• assemble the cutting machine
• set the templates system for reproduction
• set the correct gas pressure.

The assembly of the machine, the use of templates or systems of reproduction, the position of the work, the speed
range and cutting nozzles vary according to the type of the machines.
Assemble the accessories like cutting head for straight and bevel cutting with the cutting machine. (Fig 1)

Select the 1.2mm size of the cutting nozzle for 10mm thick plate.
Set the correct gas pressure of 0.15 kg/cm2 for acetylene and 1.4 to 2 kg/cm2 for oxygen for 1.2mm size nozzle.
Set the machine to run freely as per the regulated speed i.e. 50cm/min for 10mm thick plate.
Ignite the flame and adjust the neutral flame.

Set the nozzle tip to a correct distance from the surface of the plate to be cut i.e. about 7 to 8mm.
Start the machine and run to the required distance to cut the metal.
Switch ‘off’ the machine and extinguish the flame at the end of the cut.
Remove the plate, clean the iron oxide slag and inspect the cut surface.
For cutting a bevel edge tilt the cutting torch nozzle to the required angle and follow the same skill sequence
followed for straight line cutting. (Fig 2)

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CITS : C G & M - Welder - Exercise 04