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Gas Metal Arc Welding

Instructions:

Answer 50 questions in 15 minutes.
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Match each statement with the correct term.
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This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. What 2 organizations designate specifications for GMAW wires?
Constant current (CC)
Voltage is the force that overcomes resistance to allow amperage flow
AWS and CSA
15 feet (4.5 meters)

2. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Gives arc voltage values to the control system of the feeder
Higher 26 to 35 arc volts
20 to 200 times per second
The Arc voltage

3. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Reducing the gas source pressure to a constant working pressure
AWS and CSA
Higher 26 to 35 arc volts
Cause flaking - which can clog the liner and contact tube

4. What is the disadvantage of the gauge preset type of regulator/flowmeter?
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Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Generally not as accurate
Minutes of elapsed time continually run (out of 10 minutes)

5. List the factors that determine the mode of metal transfer
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Shielding the molten weld metal from atmospheric contamination
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
3

6. What would be an indication that the drive roll pressure is adjusted correctly?
When the filler wire is in direct contract with the base metal
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Wire feeds smoothly (yet will slip should a problem occur in the gun)
V groove or U groove

7. What does the term GMAW identify?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Gas metal arc welding
Shielding the molten weld metal from atmospheric contamination
(DCEP) Direct Current Electrode Positive or Reverse polarity

8. In the GMAW process what does voltage control?
The Arc voltage
Puddle fluidity
15 feet (4.5 meters)
Higher 26 to 35 arc volts

9. What does the wire feeder control?
Speed of the feed motor and - starting / stopping electrode feed
(DCEP) Direct Current Electrode Positive or Reverse polarity
15 feet (4.5 meters)
To prevent leakage - Carbon Dioxide (CO2)

10. Give a brief description of the GMAW process
Wire feed speed
Welding process that joins metals by heating them with an electric arc
By there current carrying capacity
AWS and CSA

11. Draw a typical volt amp curve for a machine that is designed for GMAW
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Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
(DCEP) Direct Current Electrode Positive or Reverse polarity
Generally not as accurate

12. What is a typical flow rate of CO2 for short circuit transfer?
Controls the rate of flow of a shielding gas to the gun nozzle
Pressure - The rate of flow of a shielding gas
5.8 to 12.5 L/min
National Electrical Manufactures Association

13. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
The Arc voltage
(DCEP) Direct Current Electrode Positive or Reverse polarity
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

14. What is an advantage of pulsed arc transfer with GMAW?
Gives arc voltage values to the control system of the feeder
Pressure vessels and the piping industry
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Aluminum wire

15. When is the metal transferred with short circuit transfer?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
These terms are quite restrictive and often technically incorrect
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
When the filler wire is in direct contract with the base metal

16. What is the purpose of the shielding gas used in GMAW?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Shielding the molten weld metal from atmospheric contamination
Welding process that joins metals by heating them with an electric arc
The negative side of a welding unit

17. What 2 controls are found on a GMAW set- up?
V groove or U groove
Wire feed speed - Voltage control
Dry ice can form within the flow control openings and cause blockage of shielding gas
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

18. List 3 forms compressed gases may be supplied for welding
Cause flaking - which can clog the liner and contact tube
Duty cycle
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
DCEP (Direct Current Electrode Positive) Reverse Polarity

19. A pull type drive system is usually used on what type of material?
To limit the short circuiting current so that spatter is reduced
Aluminum wire
3
National Electrical Manufactures Association

20. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Gives arc voltage values to the control system of the feeder
Dry ice can form within the flow control openings and cause blockage of shielding gas
...
Puddle fluidity

21. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Constant current (CC)
85%
To prevent drawing of liquid CO2 (Carbon Dioxide)
Minutes of elapsed time continually run (out of 10 minutes)

22. What type of power source is commonly used with a voltage sensing wire feeder?
By there current carrying capacity
To prevent leakage - Carbon Dioxide (CO2)
Constant current (CC)
Pressure vessels and the piping industry

23. What wire are knurled drive rolls most commonly used on?
Flux cored wires
(DCEP) Direct Current Electrode Positive or Reverse polarity
Push type: Wire is fed by a set of drive rolls located in the wire feed unit - Pull type: Drive rolls mounted in the gun itself - Push- pull type: Combination of the two
SMAW - GTAW

24. What is the purpose of a regulator and what does it indicate on its gauges?
Pressure vessels and the piping industry
5.8 to 12.5 L/min
Reducing the gas source pressure to a constant working pressure
Welding process that joins metals by heating them with an electric arc

25. Why must CO2 cylinders be used in the vertical position?
Generally not as accurate
To prevent drawing of liquid CO2 (Carbon Dioxide)
Aluminum wire
Gas metal arc welding

26. List 3 wire drive systems and give a short description of each
Push type: Wire is fed by a set of drive rolls located in the wire feed unit - Pull type: Drive rolls mounted in the gun itself - Push- pull type: Combination of the two
Wire feeds smoothly (yet will slip should a problem occur in the gun)
20 to 200 times per second
Wire feed speed - Voltage control

27. What does voltage do in an electrical circuit?
Cause flaking - which can clog the liner and contact tube
Voltage is the force that overcomes resistance to allow amperage flow
Minimum distortion due to low heat input
Motor driven generators - Transformer rectifiers - and Inverter designs

28. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
3
Puddle fluidity
Guns

29. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
Welding process that joins metals by heating them with an electric arc
5.8 to 12.5 L/min
Gas metal arc welding

30. What controls the wire speed on a voltage sensing wire feeder?
...
The Arc voltage
15 feet (4.5 meters)
If you dont know this check your phone

31. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Speed of the feed motor and - starting / stopping electrode feed
3
Gives arc voltage values to the control system of the feeder

32. Why is the term GMAW preferred over MIG or MAG?
Generally not as accurate
These terms are quite restrictive and often technically incorrect
12 to 22 arc volts
Minutes of elapsed time continually run (out of 10 minutes)

33. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Minutes of elapsed time continually run (out of 10 minutes)
DCEP (Direct Current Electrode Positive) Reverse Polarity
If you dont know this check your phone
Short- circuiting transfer - Globular transfer - Spray transfer

34. What is the recommended electrode stick- out for .035 solid wire?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
3
1/4 inch to 1/2 inch
SMAW - GTAW

35. What is the key advantage of short circuiting transfer?
Minutes of elapsed time continually run (out of 10 minutes)
SMAW - GTAW
Minimum distortion due to low heat input
Penetration and burn - off rate of the electrode

36. How are GMAW guns rated?
By there current carrying capacity
Constant current (CC)
Flux cored wires
85%

37. What is the preferred drive roll design for solid wires?
The Arc voltage
To limit the short circuiting current so that spatter is reduced
Puddle fluidity
V groove or U groove

38. What controls amperage when using GMAW?
The negative side of a welding unit
Wire feed speed
Penetration and burn - off rate of the electrode
Constant voltage (CV)

39. Why is a line heater required when using GMAW?
Generally not as accurate
Voltage is the force that overcomes resistance to allow amperage flow
Dry ice can form within the flow control openings and cause blockage of shielding gas
Guns

40. What current and polarity is generally used with GMAW?
12 to 22 arc volts
Wire feed speed - Voltage control
DCEP (Direct Current Electrode Positive) Reverse Polarity
Minimum distortion due to low heat input

41. What is the main purpose of 'slope'?
Constant current (CC)
To limit the short circuiting current so that spatter is reduced
Flux cored wires
Wire feed speed

42. What effect does increasing and decreasing the inductance have on the weld?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
V groove or U groove
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
SMAW - GTAW

43. What type of power source is used with a constant speed wire feeder?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Controls the rate of flow of a shielding gas to the gun nozzle
Constant current (CC)
Constant voltage (CV)

44. What is the required arc voltage used for short circuit transfer?
12 to 22 arc volts
15 feet (4.5 meters)
AWS and CSA
To prevent leakage - Carbon Dioxide (CO2)

45. What does inductance control?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
SMAW - GTAW
3
The time rate of response for the current rise and fall

46. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
When the filler wire is in direct contract with the base metal
Short- circuiting transfer - Globular transfer - Spray transfer
(DCEP) Direct Current Electrode Positive or Reverse polarity
Wire feed speed

47. Regulators control_____________ flowmeters SHOW____________.
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
AWS and CSA
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Pressure - The rate of flow of a shielding gas

48. What are the 2 types of wire feeders available?
Cause flaking - which can clog the liner and contact tube
Constant- speed wire feeders and Voltage- sennsing wire feeders
(DCEP) Direct Current Electrode Positive or Reverse polarity
The time rate of response for the current rise and fall

49. List several industries that would use GMAW
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20 to 200 times per second
Pressure vessels and the piping industry
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

50. What is a solenoid valve and what actuates it?
20 to 200 times per second
Wire feed speed
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Gives arc voltage values to the control system of the feeder