AWS Tools & Equipment Operation 2 — Questions and Answers
Question 1: What is the primary purpose of a wire feed speed control on a MIG welder?
- To adjust shielding gas flow
- To regulate the rate at which electrode wire is fed into the weld pool (Correct answer)
- To control the duty cycle of the machine
- To set the polarity of the electrode
Correct answer: To regulate the rate at which electrode wire is fed into the weld pool
Wire feed speed directly controls the amount of filler metal deposited per unit of time, affecting bead size and penetration.
Question 2: Which type of electrode holder is classified as 'fully insulated'?
- One with exposed copper jaws only at the tip
- One where all metal parts are covered by insulating material except the jaw contact points (Correct answer)
- One made entirely of plastic
- One used exclusively for AC welding
Correct answer: One where all metal parts are covered by insulating material except the jaw contact points
A fully insulated holder has insulation covering all metal surfaces except the jaw contact area, reducing shock hazard.
Question 3: What does the duty cycle rating on a welding machine indicate?
- The maximum amperage the machine can ever produce
- The percentage of a 10-minute period the machine can weld at rated output without overheating (Correct answer)
- The number of electrodes consumed per hour
- The efficiency of the power transformer
Correct answer: The percentage of a 10-minute period the machine can weld at rated output without overheating
Duty cycle defines safe continuous operation time; a 60% duty cycle means 6 minutes on and 4 minutes rest per 10-minute cycle.
Question 4: On an oxy-fuel cutting torch, the high-pressure oxygen cutting lever controls:
- The preheat flame temperature
- The flow of pure oxygen that oxidizes the base metal to make the cut (Correct answer)
- The acetylene pressure at the tip
- The speed of the cutting head travel
Correct answer: The flow of pure oxygen that oxidizes the base metal to make the cut
The cutting lever releases a high-velocity stream of pure oxygen that reacts with preheated iron to burn and blow away molten slag.
Question 5: What is the function of the contactor inside a welding power source?
- To convert AC to DC
- To energize the electrode circuit only when the arc is initiated or the gun trigger is pressed (Correct answer)
- To regulate primary input voltage
- To cool the transformer coils
Correct answer: To energize the electrode circuit only when the arc is initiated or the gun trigger is pressed
The contactor is a heavy-duty relay that keeps the electrode de-energized until welding begins, improving safety.
Question 6: When setting up a plasma cutter, the correct gas pressure is most critical because:
- Higher pressure always gives a cleaner cut
- Insufficient pressure causes incomplete piercing and excess dross while excessive pressure can blow out the arc (Correct answer)
- Pressure only affects cutting speed, not quality
- Gas pressure controls only the standoff distance
Correct answer: Insufficient pressure causes incomplete piercing and excess dross while excessive pressure can blow out the arc
Pressure must be within the manufacturer's specified range to maintain a stable plasma column and produce clean, dross-free cuts.
Question 7: A welding cable's ampacity rating must be selected based on:
- The brand of the welding machine only
- The maximum welding current and the duty cycle at which it will operate (Correct answer)
- The length of the cable alone
- The type of electrode coating used
Correct answer: The maximum welding current and the duty cycle at which it will operate
Cable ampacity depends on current load and the percentage of time that current flows; undersized cables overheat and become a fire hazard.
AWS Tools & Equipment Operation 2
What is the primary purpose of a wire feed speed control on a MIG welder?