6.1 State TWO causes of undercutting in an arc-welded joint - NSC Mechanical Technology Automotive - 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 Automotive - Question 6 - 2017 - Paper 1
Step 1
State TWO causes of undercutting in an arc-welded joint.
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Answer
One cause of undercutting can be a high current setting, which can lead to excessive melting and insufficient fusion.
Another cause is the incorrect electrode size, which may not provide adequate welding depth and can affect stability.
Step 2
How would you prevent slag inclusion in an arc-welded joint?
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Answer
To prevent slag inclusion, ensure you:
Chip off any slag from previous welds before continuing.
Clean the joint thoroughly before starting the welding process.
Step 3
Describe how the liquid dye penetration test is done on a welded joint.
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Answer
The liquid dye penetration test involves the following steps:
Apply dye spray onto the clean surface of the weld area.
Allow a short period for the dye to penetrate into any cracks or voids.
Remove excess dye with a solvent and wash the area to remove any residues.
Apply a developer to reveal the presence of dye, which will show any defects.
Step 4
Name THREE advantages of the use of MIG/MAGS welding rather than arc welding.
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Answer
MIG/MAGS welding requires less skill from the operator, making it more accessible.
Continuous welds can be executed without frequent electrode replacements, leading to increased efficiency.
It facilitates quicker welds, which decreases overall production time.
Step 5
State TWO functions of the gas flow meter.
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Answer
The gas flow meter regulates the flow of shielding gas during the welding process.
It measures the rate of flow to ensure optimal shielding conditions.
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 shielding gas serves to control the welding arc and protects the molten pool from atmospheric contamination, ensuring a high-quality weld.
Step 8
Why must the earth cable be properly connected to the parent metal?
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The earth cable must be connected to complete the electrical circuit, which is essential for maintaining a consistent current flow and preventing electric shock.
Step 9
Name THREE types of gases used for MIG/MAGS welding.
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