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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.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

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 term is used to describe when the workpiece is hooked to the negative pole on the power source?
(DCEP) Direct Current Electrode Positive or Reverse polarity
If you dont know this check your phone
Puddle fluidity
Welding process that joins metals by heating them with an electric arc

2. When is the metal transferred with short circuit transfer?
Minimum distortion due to low heat input
When the filler wire is in direct contract with the base metal
12 to 22 arc volts
To prevent drawing of liquid CO2 (Carbon Dioxide)

3. What happens when the electrode extension is increased?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
These terms are quite restrictive and often technically incorrect
Pressure - The rate of flow of a shielding gas
The resistace to electrical current flow increases with it. Causing the electrode to heat

4. List 3 wire drive systems and give a short description of each
Generally not as accurate
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
Speed of the feed motor and - starting / stopping electrode feed
The resistace to electrical current flow increases with it. Causing the electrode to heat

5. What are the 2 types of wire feeders available?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
12 to 22 arc volts
Constant- speed wire feeders and Voltage- sennsing wire feeders
Guns

6. What is another term for electrode holders for GMAW?
3
Minimum distortion due to low heat input
Guns
The Arc voltage

7. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
...
Speed of the feed motor and - starting / stopping electrode feed
5.8 to 12.5 L/min
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

8. Regulators control_____________ flowmeters SHOW____________.
Pressure - The rate of flow of a shielding gas
When the filler wire is in direct contract with the base metal
Gas metal arc welding
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9. What is the disadvantage of the gauge preset type of regulator/flowmeter?
To prevent leakage - Carbon Dioxide (CO2)
DCEP (Direct Current Electrode Positive) Reverse Polarity
Gives arc voltage values to the control system of the feeder
Generally not as accurate

10. Why is the term GMAW preferred over MIG or MAG?
Speed of the feed motor and - starting / stopping electrode feed
These terms are quite restrictive and often technically incorrect
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Minimum distortion due to low heat input

11. What is the purpose of the shielding gas used in GMAW?
Wire feed speed
Speed of the feed motor and - starting / stopping electrode feed
Short- circuiting transfer - Globular transfer - Spray transfer
Shielding the molten weld metal from atmospheric contamination

12. What power sources are used with the GMAW Process?
Wire feed speed
Motor driven generators - Transformer rectifiers - and Inverter designs
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

13. What is an advantage of pulsed arc transfer with GMAW?
Insufficient current to melt the wire off cleanly
The Arc voltage
Reducing the gas source pressure to a constant working pressure
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

14. What type of power source is used with a constant speed wire feeder?
To prevent leakage - Carbon Dioxide (CO2)
Constant current (CC)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Constant voltage (CV)

15. What type of power source is commonly used with a voltage sensing wire feeder?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Constant current (CC)
AWS and CSA

16. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Controls the rate of flow of a shielding gas to the gun nozzle
Dry ice can form within the flow control openings and cause blockage of shielding gas
National Electrical Manufactures Association

17. How many times per second does short circuiting take place?
20 to 200 times per second
Shielding the molten weld metal from atmospheric contamination
Generally not as accurate
Higher 26 to 35 arc volts

18. Draw a typical volt amp curve for a machine that is designed for GMAW
AWS and CSA
Reducing the gas source pressure to a constant working pressure
1/4 inch to 1/2 inch
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19. What is the maximum distance that hard wire can be successfully pushed?
15 feet (4.5 meters)
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
Short- circuiting transfer - Globular transfer - Spray transfer
Dry ice can form within the flow control openings and cause blockage of shielding gas

20. List the basic equipment requirements for the GMAW process
Welding process that joins metals by heating them with an electric arc
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

21. With straight polarity where is 2/3 of the arc energy?
By there current carrying capacity
The negative side of a welding unit
Pressure vessels and the piping industry
Minimum distortion due to low heat input

22. What is a solenoid valve and what actuates it?
85%
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
By there current carrying capacity

23. Why is a line heater required when using GMAW?
SMAW - GTAW
Dry ice can form within the flow control openings and cause blockage of shielding gas
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
National Electrical Manufactures Association

24. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Shielding the molten weld metal from atmospheric contamination
Cause flaking - which can clog the liner and contact tube
Speed of the feed motor and - starting / stopping electrode feed

25. List the three methods of metal transfer with GMAW
The resistace to electrical current flow increases with it. Causing the electrode to heat
Puddle fluidity
To limit the short circuiting current so that spatter is reduced
Short- circuiting transfer - Globular transfer - Spray transfer

26. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
Controls the rate of flow of a shielding gas to the gun nozzle
The Arc voltage
12 to 22 arc volts

27. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Shielding the molten weld metal from atmospheric contamination
The time rate of response for the current rise and fall
Gives arc voltage values to the control system of the feeder

28. What is the required arc voltage used for short circuit transfer?
12 to 22 arc volts
The resistace to electrical current flow increases with it. Causing the electrode to heat
The time rate of response for the current rise and fall
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

29. List several industries that would use GMAW
DCEP (Direct Current Electrode Positive) Reverse Polarity
To prevent drawing of liquid CO2 (Carbon Dioxide)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Pressure vessels and the piping industry

30. What 2 organizations designate specifications for GMAW wires?
Higher 26 to 35 arc volts
Shielding the molten weld metal from atmospheric contamination
DCEP (Direct Current Electrode Positive) Reverse Polarity
AWS and CSA

31. What output on the welding machine is used to rate the duty cycle?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Minutes of elapsed time continually run (out of 10 minutes)
When the filler wire is in direct contract with the base metal
The Arc voltage

32. Give a description of 'pinch effect'
Puddle fluidity
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
20 to 200 times per second
Speed of the feed motor and - starting / stopping electrode feed

33. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
20 to 200 times per second
85%
Controls the rate of flow of a shielding gas to the gun nozzle
Dry ice can form within the flow control openings and cause blockage of shielding gas

34. What controls amperage when using GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Wire feed speed
Flux cored wires

35. What does voltage do in an electrical circuit?
AWS and CSA
To prevent leakage - Carbon Dioxide (CO2)
1/4 inch to 1/2 inch
Voltage is the force that overcomes resistance to allow amperage flow

36. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Motor driven generators - Transformer rectifiers - and Inverter designs
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
If you dont know this check your phone
Generally not as accurate

37. What does the abbreviation NEMA stand for?
5.8 to 12.5 L/min
15 feet (4.5 meters)
National Electrical Manufactures Association
...

38. What controls the wire speed on a voltage sensing wire feeder?
V groove or U groove
The Arc voltage
Pressure vessels and the piping industry
To prevent drawing of liquid CO2 (Carbon Dioxide)

39. What processes are constant current (CC) power sources designed to be used with?
Penetration and burn - off rate of the electrode
SMAW - GTAW
Speed of the feed motor and - starting / stopping electrode feed
Generally not as accurate

40. What is a typical flow rate of CO2 for short circuit transfer?
Reducing the gas source pressure to a constant working pressure
To prevent leakage - Carbon Dioxide (CO2)
5.8 to 12.5 L/min
Puddle fluidity

41. What would be an indication that the drive roll pressure is adjusted correctly?
Welding process that joins metals by heating them with an electric arc
Puddle fluidity
Wire feeds smoothly (yet will slip should a problem occur in the gun)
The resistace to electrical current flow increases with it. Causing the electrode to heat

42. What is the main purpose of 'slope'?
5.8 to 12.5 L/min
To limit the short circuiting current so that spatter is reduced
20 to 200 times per second
Constant- speed wire feeders and Voltage- sennsing wire feeders

43. What does the term GMAW identify?
1/4 inch to 1/2 inch
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
Gas metal arc welding
3

44. What 2 controls are found on a GMAW set- up?
National Electrical Manufactures Association
1/4 inch to 1/2 inch
Shielding the molten weld metal from atmospheric contamination
Wire feed speed - Voltage control

45. What is the purpose of a regulator and what does it indicate on its gauges?
Reducing the gas source pressure to a constant working pressure
Spatter problems and poor weld appearance
To prevent leakage - Carbon Dioxide (CO2)
By there current carrying capacity

46. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
If you dont know this check your phone
(DCEP) Direct Current Electrode Positive or Reverse polarity
To prevent leakage - Carbon Dioxide (CO2)

47. In the GMAW process what does voltage control?
Puddle fluidity
By there current carrying capacity
3
1/4 inch to 1/2 inch

48. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
Controls the rate of flow of a shielding gas to the gun nozzle
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Generally not as accurate

49. What is the key advantage of short circuiting transfer?
Reducing the gas source pressure to a constant working pressure
Minimum distortion due to low heat input
Constant current (CC)
To prevent leakage - Carbon Dioxide (CO2)

50. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
Wire feed speed - Voltage control
Controls the rate of flow of a shielding gas to the gun nozzle
Puddle fluidity