6.1 State TWO causes of undercutting in an arc-welded joint - NSC Mechanical Technology Welding and Metalwork - Question 6 - 2017 - Paper 1
Question 6
6.1 State TWO causes of undercutting in an arc-welded joint.
6.2 How would you prevent slag inclusion in an arc-welded joint?
6.3 Describe how the liquid dye penet... show full transcript
Worked Solution & Example Answer:6.1 State TWO causes of undercutting in an arc-welded joint - NSC Mechanical Technology Welding and Metalwork - Question 6 - 2017 - Paper 1
Step 1
State TWO causes of undercutting in an arc-welded joint.
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Answer
Current setting is too high.
Welding speed is too fast.
Step 2
How would you prevent slag inclusion in an arc-welded joint?
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Answer
Ensure the joint is properly cleaned before welding is done.
Chip off the slag from previous weld runs before continuing.
Step 3
Describe how the liquid dye penetration test is done on a welded joint.
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Answer
The process involves the following steps:
Spray dye onto the clean surface of the weld to be inspected.
Allow a short time for the dye to penetrate, then remove any excess dye with a solvent.
Wash the surface with water and allow it to dry.
Finally, spray a developer on the surface to reveal any dye trapped in cracks or pinholes.
Step 4
Name THREE advantages of the use of MIG/MAGS welding rather than arc welding.
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Answer
Operator needs less skills to operate MIG/MAGS compared to arc welding.
Continuous welds can be made without replacing electrodes, minimizing downtime.
It is a quicker process, allowing for faster production times.
Step 5
State TWO functions of the gas flow meter.
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Answer
Control the flow rate of shielding gas.
Measure the flow rate of the gas during the welding process.
Step 6
Label the parts A–E in the illustration of the MIG/MAGS-welding process.
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Answer
A = Melted welding pool / Parent metal / Weld metal / Weld
B = Contact nozzle / Weld pistol / gun
C = Gas shroud / Weld pistol / gun
D = Shielding gas
E = Earth clamp / Skelm / Earth cable
Step 7
What is the purpose of the shielding gas in the MIG/MAGS welding process?
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Answer
The purpose of the shielding gas is to control the welding arc and to shield the molten pool from atmospheric gases that could contaminate it.
Step 8
Why must the earth cable be properly connected to the parent metal?
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To complete the circuit, maintain constant current, and prevent electric shock.
Step 9
Name THREE types of gases used for MIG/MAGS welding.
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