456A GMAW MIG 2

Question 1

What is the difference between push (forehand) and pull (backhand) gun angle in GMAW?

Accepted Answer

Push angle tilts the gun in the direction of travel for less penetration and wider bead; pull angle tilts away from travel direction for deeper penetration and narrower bead

Answer

Push (forehand) technique tilts the gun 10-15° in the direction of travel, placing the arc ahead of the puddle. This produces less penetration, a wider/flatter bead, and better visibility. Pull (backhand) tilts the gun 10-15° away from the direction of travel, producing deeper penetration, a narrower/more convex bead, and more spatter.

Question 2

What is the purpose of anti-spatter compound in GMAW welding?

Accepted Answer

To coat the nozzle, workpiece surface, and fixtures to prevent spatter from adhering, making cleanup easier

Answer

Anti-spatter compound is applied to the inside of the gas nozzle, the workpiece surface near the weld, and fixtures/clamps. It prevents molten spatter from welding onto these surfaces, reducing cleanup time and preventing nozzle blockage. It must not be applied to the weld joint itself as it can contaminate the weld.

Question 3

What causes excessive spatter in GMAW welding?

Accepted Answer

Voltage set too high or too low for the wire feed speed, contaminated base metal, wrong shielding gas, excessive stick-out, or moisture on the wire

Answer

Excessive spatter results from: voltage too low (unstable short-circuit transfer), voltage too high (long arc, excessive droplet spray), contaminated or rusty base metal, wrong or depleted shielding gas, excessive stick-out, moisture on the wire or base metal, or worn/wrong-sized contact tip. Proper parameter balance minimizes spatter.

Question 4

What is pulsed GMAW and what are its advantages?

Accepted Answer

An electronically controlled process that alternates between high peak current (for droplet transfer) and low background current (to maintain the arc), allowing spray-type transfer at lower average heat input

Answer

Pulsed GMAW uses a power source that rapidly switches between high peak current (which detaches a single droplet per pulse in a spray-like manner) and low background current (which maintains the arc without metal transfer). This provides the quality of spray transfer with lower average heat input, enabling use on thinner materials and in all positions.

Question 5

What is the correct procedure for setting up a GMAW machine for a new welding job?

Accepted Answer

Select correct wire size and type, install matching drive rolls and contact tip, set gas type and flow rate, adjust wire feed speed and voltage per the manufacturer's chart, and make test welds

Answer

Proper GMAW setup includes: (1) selecting the correct wire type and diameter for the application, (2) installing matching drive rolls, liner, and contact tip, (3) selecting the correct shielding gas and setting the flow rate (typically 15-20 L/min), (4) setting wire feed speed and voltage using the manufacturer's parameter chart, (5) adjusting stick-out, and (6) making test welds to fine-tune.

Red Seal Welder 456A Practice Test

Red Seal Welder 456A Practice Test

456A GMAW MIG 2