456A MIG/FCAW (GMAW & Flux-Cored Arc Welding) 4

Question 1

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

Accepted Answer

Transfers current to the wire and guides the wire accurately to the arc

Answer

The contact tip (made of copper alloy) transfers welding current from the gun body to the electrode wire through electrical contact as the wire slides through it. It also guides the wire accurately toward the weld joint. Contact tips must match the wire diameter and should be replaced when worn oval or spattered shut.

Question 2

What is 'cold wire inclusions' or 'cold laps' in FCAW welding and how are they prevented?

Accepted Answer

Unmelted wire tips fused onto the weld surface; prevented by proper voltage and maintaining correct torch angle

Answer

Cold wire inclusions occur when the wire tip is not fully melted before contacting the weld pool or base metal, leaving an unmelted wire stub. Proper voltage settings ensure the wire melts completely in the arc. Torch angle must keep the arc in the leading edge of the pool.

Question 3

What is the recommended technique for welding a vertical-up fillet weld with GMAW short-circuit transfer?

Accepted Answer

Triangular or Z-weave pattern with pauses at the toes to build up metal and prevent sagging

Answer

Vertical-up GMAW (short-circuit) typically uses a triangular or Z-weave pattern. Pausing slightly at each toe ensures fusion to the base metal and builds up the weld profile. The upward travel direction allows gravity to support the solidifying weld pool and prevents undercutting.

Question 4

What is the difference between E70T-1 and E71T-1 FCAW electrodes?

Accepted Answer

E70T-1 is limited to flat/horizontal positions; E71T-1 is all-position including vertical-up and overhead

Answer

In the FCAW electrode classification, the digit after 'E7' indicates position: '0' means flat and horizontal only, '1' means all positions. E70T-1 is a flat/horizontal electrode producing a large, fluid slag; E71T-1 has a fast-freezing slag system designed for out-of-position welding.

Question 5

What does 'nozzle-to-work distance' (also called contact-tip-to-work distance or stick-out) affect in FCAW?

Accepted Answer

Resistance preheating of the wire, affecting current draw, deposition rate, and penetration

Answer

In FCAW, as in GMAW, the wire stick-out distance affects the resistive preheating of the wire between the contact tip and the arc. Longer stick-out preheats the wire more, reduces actual welding current (at the same wire feed speed), and lowers penetration. It is a critical variable specified in the WPS.

Red Seal Welder 456A Practice Test

Red Seal Welder 456A Practice Test

456A MIG/FCAW (GMAW & Flux-Cored Arc Welding) 4