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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. Give a description of 'pinch effect'
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
By there current carrying capacity
Pressure - The rate of flow of a shielding gas
Higher 26 to 35 arc volts

2. What is the effect of too much slope?
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Insufficient current to melt the wire off cleanly
85%
Dry ice can form within the flow control openings and cause blockage of shielding gas

3. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Spatter problems and poor weld appearance
When the filler wire is in direct contract with the base metal
85%
Dry ice can form within the flow control openings and cause blockage of shielding gas

4. What power sources are used with the GMAW Process?
Constant- speed wire feeders and Voltage- sennsing wire feeders
V groove or U groove
Motor driven generators - Transformer rectifiers - and Inverter designs
Dry ice can form within the flow control openings and cause blockage of shielding gas

5. Why must CO2 cylinders be used in the vertical position?
Welding process that joins metals by heating them with an electric arc
To prevent drawing of liquid CO2 (Carbon Dioxide)
Guns
1/4 inch to 1/2 inch

6. List the three methods of metal transfer with GMAW
Gives arc voltage values to the control system of the feeder
Short- circuiting transfer - Globular transfer - Spray transfer
V groove or U groove
Minimum distortion due to low heat input

7. What controls amperage when using GMAW?
Wire feed speed
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Puddle fluidity
To prevent leakage - Carbon Dioxide (CO2)

8. When is the metal transferred with short circuit transfer?
Wire feed speed
Controls the rate of flow of a shielding gas to the gun nozzle
Speed of the feed motor and - starting / stopping electrode feed
When the filler wire is in direct contract with the base metal

9. What is another term for electrode holders for GMAW?
Guns
When the filler wire is in direct contract with the base metal
Cause flaking - which can clog the liner and contact tube
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

10. What is the preferred drive roll design for solid wires?
Constant current (CC)
V groove or U groove
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3

11. What does the term GMAW identify?
Gas metal arc welding
SMAW - GTAW
Pressure vessels and the piping industry
Higher 26 to 35 arc volts

12. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
Generally not as accurate
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When the filler wire is in direct contract with the base metal

13. List the factors that determine the mode of metal transfer
Penetration and burn - off rate of the electrode
Guns
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Minimum distortion due to low heat input

14. What wire are knurled drive rolls most commonly used on?
The Arc voltage
Flux cored wires
Cause flaking - which can clog the liner and contact tube
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

15. What type of power source is commonly used with a voltage sensing wire feeder?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
AWS and CSA
Constant current (CC)

16. What is a typical flow rate of CO2 for short circuit transfer?
...
Insufficient current to melt the wire off cleanly
Higher 26 to 35 arc volts
5.8 to 12.5 L/min

17. Why is a line heater required when using GMAW?
15 feet (4.5 meters)
AWS and CSA
5.8 to 12.5 L/min
Dry ice can form within the flow control openings and cause blockage of shielding gas

18. What does inductance control?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Higher 26 to 35 arc volts
Guns
The time rate of response for the current rise and fall

19. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Constant current (CC)
12 to 22 arc volts
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

20. In the GMAW process what does amperage control?
Gives arc voltage values to the control system of the feeder
Flux cored wires
To prevent drawing of liquid CO2 (Carbon Dioxide)
Penetration and burn - off rate of the electrode

21. With straight polarity where is 2/3 of the arc energy?
Constant current (CC)
The negative side of a welding unit
Flux cored wires
Penetration and burn - off rate of the electrode

22. List 3 wire drive systems and give a short description of each
V groove or U groove
Generally not as accurate
National Electrical Manufactures Association
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

23. What happens when the electrode extension is increased?
Controls the rate of flow of a shielding gas to the gun nozzle
Insufficient current to melt the wire off cleanly
The resistace to electrical current flow increases with it. Causing the electrode to heat
15 feet (4.5 meters)

24. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Cause flaking - which can clog the liner and contact tube
Motor driven generators - Transformer rectifiers - and Inverter designs
Guns
Higher 26 to 35 arc volts

25. Regulators control_____________ flowmeters SHOW____________.
V groove or U groove
When the filler wire is in direct contract with the base metal
Pressure - The rate of flow of a shielding gas
15 feet (4.5 meters)

26. What is the maximum distance that hard wire can be successfully pushed?
When the filler wire is in direct contract with the base metal
Pressure vessels and the piping industry
5.8 to 12.5 L/min
15 feet (4.5 meters)

27. What output on the welding machine is used to rate the duty cycle?
AWS and CSA
Minutes of elapsed time continually run (out of 10 minutes)
12 to 22 arc volts
DCEP (Direct Current Electrode Positive) Reverse Polarity

28. In the GMAW process what does voltage control?
AWS and CSA
When the filler wire is in direct contract with the base metal
Puddle fluidity
Generally not as accurate

29. Draw a typical volt amp curve for a machine that is designed for GMAW
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Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Reducing the gas source pressure to a constant working pressure
To prevent leakage - Carbon Dioxide (CO2)

30. Why is the term GMAW preferred over MIG or MAG?
Generally not as accurate
Welding process that joins metals by heating them with an electric arc
12 to 22 arc volts
These terms are quite restrictive and often technically incorrect

31. How many times per second does short circuiting take place?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Controls the rate of flow of a shielding gas to the gun nozzle
National Electrical Manufactures Association
20 to 200 times per second

32. What is the required arc voltage used for short circuit transfer?
Duty cycle
Penetration and burn - off rate of the electrode
12 to 22 arc volts
Controls the rate of flow of a shielding gas to the gun nozzle

33. What effect does increasing and decreasing the inductance have on the weld?
Generally not as accurate
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
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

34. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
When the filler wire is in direct contract with the base metal
(DCEP) Direct Current Electrode Positive or Reverse polarity
Constant current (CC)

35. 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
The resistace to electrical current flow increases with it. Causing the electrode to heat
Voltage is the force that overcomes resistance to allow amperage flow
These terms are quite restrictive and often technically incorrect

36. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
AWS and CSA
National Electrical Manufactures Association
If you dont know this check your phone
Wire feeds smoothly (yet will slip should a problem occur in the gun)

37. What is the purpose of the shielding gas used in GMAW?
Pressure vessels and the piping industry
Shielding the molten weld metal from atmospheric contamination
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

38. How are GMAW guns rated?
By there current carrying capacity
To limit the short circuiting current so that spatter is reduced
The negative side of a welding unit
Wire feed speed - Voltage control

39. What is a solenoid valve and what actuates it?
Aluminum wire
Minutes of elapsed time continually run (out of 10 minutes)
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

40. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Reducing the gas source pressure to a constant working pressure
85%
Gives arc voltage values to the control system of the feeder
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

41. What is an advantage of pulsed arc transfer with GMAW?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Motor driven generators - Transformer rectifiers - and Inverter designs
Aluminum wire
Minutes of elapsed time continually run (out of 10 minutes)

42. What would be an indication that the drive roll pressure is adjusted correctly?
5.8 to 12.5 L/min
Controls the rate of flow of a shielding gas to the gun nozzle
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

43. 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
Pressure - The rate of flow of a shielding gas
The negative side of a welding unit

44. List the basic equipment requirements for the GMAW process
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Insufficient current to melt the wire off cleanly
...
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

45. What are the 2 types of wire feeders available?
Duty cycle
Dry ice can form within the flow control openings and cause blockage of shielding gas
Constant- speed wire feeders and Voltage- sennsing wire feeders
Gas metal arc welding

46. List several industries that would use GMAW
Welding process that joins metals by heating them with an electric arc
Constant- speed wire feeders and Voltage- sennsing wire feeders
Generally not as accurate
Pressure vessels and the piping industry

47. What type of power source is used with a constant speed wire feeder?
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
Controls the rate of flow of a shielding gas to the gun nozzle
Constant voltage (CV)

48. What is the main purpose of 'slope'?
Spatter problems and poor weld appearance
Minimum distortion due to low heat input
The negative side of a welding unit
To limit the short circuiting current so that spatter is reduced

49. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
To prevent drawing of liquid CO2 (Carbon Dioxide)
Gas metal arc welding
V groove or U groove

50. What 2 controls are found on a GMAW set- up?
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
Shielding the molten weld metal from atmospheric contamination
SMAW - GTAW
Wire feed speed - Voltage control