Certified Welder Welding Processes and Equipment 2 — Questions and Answers
Question 1: What does the term 'duty cycle' mean when applied to a welding power source?
- The number of electrodes used per hour
- The percentage of a 10-minute period the machine can weld at a rated output (Correct answer)
- The maximum amperage the machine can ever produce
- The frequency of AC current output
Correct answer: The percentage of a 10-minute period the machine can weld at a rated output
Duty cycle is the percentage of a 10-minute period that a machine can operate at its rated amperage without overheating.
Question 2: Which welding process uses a non-consumable tungsten electrode and a separate filler rod?
- SMAW
- FCAW
- GTAW (Correct answer)
- SAW
Correct answer: GTAW
Gas Tungsten Arc Welding (GTAW/TIG) uses a non-consumable tungsten electrode with a separate filler metal added manually.
Question 3: In Submerged Arc Welding (SAW), what is the purpose of the granular flux?
- It cools the weld pool rapidly
- It shields the arc and weld pool from atmospheric contamination (Correct answer)
- It provides the primary filler metal
- It stabilizes the electrical current
Correct answer: It shields the arc and weld pool from atmospheric contamination
In SAW, the granular flux covers the arc and molten weld pool, shielding it from atmospheric gases and stabilizing the arc.
Question 4: What type of current is most commonly used for GTAW when welding aluminum?
- DCEP (DC Electrode Positive)
- DCEN (DC Electrode Negative)
- AC (Alternating Current) (Correct answer)
- High-frequency DC
Correct answer: AC (Alternating Current)
AC current is used for GTAW on aluminum because the electrode-positive half-cycle provides oxide cleaning action on the aluminum surface.
Question 5: Which component in a GMAW setup controls the rate at which wire is fed to the welding gun?
- The shielding gas regulator
- The wire feed unit (wire feeder) (Correct answer)
- The contact tip
- The power source transformer
Correct answer: The wire feed unit (wire feeder)
The wire feed unit drives the electrode wire from the spool to the welding gun at a speed set by the operator.
Question 6: What is plasma arc cutting (PAC) most similar to in terms of operating principle?
- Oxyfuel cutting
- GTAW with high amperage (Correct answer)
- Carbon arc gouging
- Laser cutting
Correct answer: GTAW with high amperage
Plasma arc cutting uses a constricted arc similar to GTAW but with a high-velocity plasma jet to cut through metal.
Question 7: In FCAW, what distinguishes a self-shielded wire from a gas-shielded wire?
- Self-shielded wire is solid; gas-shielded wire is tubular
- Self-shielded wire generates its own shielding from core compounds; gas-shielded requires external gas (Correct answer)
- Self-shielded wire requires DCEN; gas-shielded requires DCEP
- Self-shielded wire is used only indoors
Correct answer: Self-shielded wire generates its own shielding from core compounds; gas-shielded requires external gas
Self-shielded FCAW electrodes contain flux compounds in the core that produce shielding gas and slag, eliminating the need for external shielding gas.
Certified Welder Welding Processes and Equipment 2
What does the term 'duty cycle' mean when applied to a welding power source?