CCC Welding & Metalworking Techniques 1 — Questions and Answers
Question 1: Which welding process is most commonly used for MIG (GMAW) welding in collision repair shops?
- Shielded Metal Arc Welding (SMAW)
- Gas Metal Arc Welding (GMAW) (Correct answer)
- Tungsten Inert Gas (TIG) welding
- Flux-Cored Arc Welding (FCAW)
Correct answer: Gas Metal Arc Welding (GMAW)
Gas Metal Arc Welding (GMAW), commonly called MIG welding, is the industry standard in collision repair due to its speed, ease of use, and clean welds on automotive steel.
Question 2: What shielding gas mixture is most commonly recommended for MIG welding mild steel in automotive collision repair?
- 100% Argon
- 75% Argon / 25% CO2 (Correct answer)
- 100% CO2
- 50% Argon / 50% Helium
Correct answer: 75% Argon / 25% CO2
A 75% Argon / 25% CO2 mix (C25) provides excellent arc stability, good penetration, and minimal spatter, making it the standard choice for welding mild steel panels.
Question 3: When sectioning a pillar or rocker panel, where should the weld seam be placed according to best collision repair practices?
- At the point of greatest damage
- At the factory seam location
- In the center of the replacement panel
- At least 2 inches from any factory seam or joint (Correct answer)
Correct answer: At least 2 inches from any factory seam or joint
Industry guidelines require sectioning welds to be placed at least 2 inches away from factory seams or joints to avoid weakening structural areas already subjected to stress.
Question 4: Which type of weld is primarily used to join two overlapping panels in collision repair?
- Butt weld
- Lap weld (Correct answer)
- T-joint weld
- Edge weld
Correct answer: Lap weld
Lap welds join two overlapping panels and are extensively used in collision repair when replacing body panels that are spot-welded from the factory.
Question 5: What is the purpose of a stitch weld (skip weld) technique when welding automotive sheet metal?
- To increase penetration depth
- To reduce heat buildup and panel warpage (Correct answer)
- To create a stronger continuous bead
- To apply weld in a single pass
Correct answer: To reduce heat buildup and panel warpage
Stitch welding uses alternating weld and skip intervals to allow the metal to cool between passes, preventing excessive heat buildup that causes panel warping.
Question 6: When replacing a factory spot weld, which method is preferred to replicate the original bond in collision repair?
- Plug weld using a MIG welder
- TIG spot weld
- Resistance spot weld or plug weld (Correct answer)
- Flux-cored tack weld
Correct answer: Resistance spot weld or plug weld
Resistance spot welding exactly replicates the OEM process; when not available, plug welds via MIG are the accepted alternative, making either method preferred depending on equipment availability.
Question 7: What wire diameter is most commonly used for welding thin automotive body panels (18–20 gauge) in collision repair?
- 0.035 inch (0.9 mm)
- 0.030 inch (0.8 mm)
- 0.045 inch (1.2 mm)
- 0.023 inch (0.6 mm) (Correct answer)
Correct answer: 0.023 inch (0.6 mm)
0.023 inch (0.6 mm) wire is preferred for thin gauge automotive sheet metal because it deposits less heat and material, reducing the risk of burn-through.
CCC Welding & Metalworking Techniques 1
Which welding process is most commonly used for MIG (GMAW) welding in collision repair shops?