456A GMAW MIG

Question 1

What are the two main modes of metal transfer in GMAW (MIG) welding?

Accepted Answer

Short-circuit (short arc) transfer and spray transfer — with globular and pulsed spray as additional modes

Answer

Stick transfer and flux transfer

Answer

Gravity transfer and magnetic transfer

Answer

Continuous transfer and intermittent transfer

Question 2

What shielding gas or gas mixture is most commonly used for GMAW welding of carbon steel?

Accepted Answer

75% argon / 25% CO₂ (C25) or 90% argon / 10% CO₂

Answer

Pure argon (100%)

Answer

100% CO₂

Answer

Pure helium

Question 3

What is wire feed speed (WFS) in GMAW and what does it control?

Accepted Answer

The rate at which the filler wire is fed to the arc; it directly controls the welding amperage in constant-voltage systems

Answer

The speed the welder moves along the joint

Answer

The speed of the shielding gas flow

Answer

The speed of the cooling water flow

Question 4

What is the function of the contact tip in a GMAW gun?

Accepted Answer

To transfer welding current to the wire and guide it precisely to the weld joint

Answer

To start the arc by creating a spark

Answer

To regulate the shielding gas flow

Answer

To cool the welding wire

Question 5

What is the correct contact-tip-to-work distance (CTWD) or stick-out for GMAW on carbon steel?

Accepted Answer

10 to 19 mm (3/8 to 3/4 in.)

Answer

3 to 6 mm (1/8 to 1/4 in.)

Answer

25 to 38 mm (1 to 1-1/2 in.)

Answer

50 mm (2 in.) minimum

Question 6

What is a bird's nest or wire tangle in GMAW, and what causes it?

Accepted Answer

A tangle of wire at the drive rolls caused by a blockage in the liner, worn contact tip, excessive drive roll pressure, or wire feeding issues

Answer

A decorative weld pattern

Answer

A type of weld defect in the finished joint

Answer

A pattern used for vertical-up welding