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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 is the effect of too much slope?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Insufficient current to melt the wire off cleanly
Cause flaking - which can clog the liner and contact tube
The negative side of a welding unit

2. What happens when the electrode extension is increased?
Guns
The resistace to electrical current flow increases with it. Causing the electrode to heat
Spatter problems and poor weld appearance
DCEP (Direct Current Electrode Positive) Reverse Polarity

3. Give a description of 'pinch effect'
3
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
These terms are quite restrictive and often technically incorrect
To prevent drawing of liquid CO2 (Carbon Dioxide)

4. List the three methods of metal transfer with GMAW
Speed of the feed motor and - starting / stopping electrode feed
Short- circuiting transfer - Globular transfer - Spray transfer
85%
To prevent leakage - Carbon Dioxide (CO2)

5. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Higher 26 to 35 arc volts
Constant current (CC)
3
15 feet (4.5 meters)

6. What wire are knurled drive rolls most commonly used on?
Shielding the molten weld metal from atmospheric contamination
Duty cycle
Constant voltage (CV)
Flux cored wires

7. How many times per second does short circuiting take place?
Higher 26 to 35 arc volts
When the filler wire is in direct contract with the base metal
20 to 200 times per second
Duty cycle

8. Draw a typical volt amp curve for a machine that is designed for GMAW
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20 to 200 times per second
Insufficient current to melt the wire off cleanly
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

9. What is the key advantage of short circuiting transfer?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Minimum distortion due to low heat input
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...

10. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
The Arc voltage
To prevent drawing of liquid CO2 (Carbon Dioxide)
12 to 22 arc volts
...

11. What does the abbreviation NEMA stand for?
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
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

12. When is the metal transferred with short circuit transfer?
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Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
When the filler wire is in direct contract with the base metal
The time rate of response for the current rise and fall

13. What is a solenoid valve and what actuates it?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Pressure - The rate of flow of a shielding gas
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

14. Why is the term GMAW preferred over MIG or MAG?
Pressure - The rate of flow of a shielding gas
Constant- speed wire feeders and Voltage- sennsing wire feeders
The time rate of response for the current rise and fall
These terms are quite restrictive and often technically incorrect

15. In the GMAW process what does amperage control?
Speed of the feed motor and - starting / stopping electrode feed
Flux cored wires
Penetration and burn - off rate of the electrode
Minimum distortion due to low heat input

16. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Motor driven generators - Transformer rectifiers - and Inverter designs
Gives arc voltage values to the control system of the feeder
Shielding the molten weld metal from atmospheric contamination
...

17. 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
Generally not as accurate
AWS and CSA
Short- circuiting transfer - Globular transfer - Spray transfer

18. Why is globular transfer generally avoided with GMAW?
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
Spatter problems and poor weld appearance
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
12 to 22 arc volts

19. What processes are constant current (CC) power sources designed to be used with?
3
National Electrical Manufactures Association
Guns
SMAW - GTAW

20. List the basic equipment requirements for the GMAW process
To limit the short circuiting current so that spatter is reduced
Constant current (CC)
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

21. What output on the welding machine is used to rate the duty cycle?
Minutes of elapsed time continually run (out of 10 minutes)
12 to 22 arc volts
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
These terms are quite restrictive and often technically incorrect

22. What is an advantage of pulsed arc transfer with GMAW?
85%
Short- circuiting transfer - Globular transfer - Spray transfer
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Cause flaking - which can clog the liner and contact tube

23. What does the term GMAW identify?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Gas metal arc welding
Pressure - The rate of flow of a shielding gas
Short- circuiting transfer - Globular transfer - Spray transfer

24. A pull type drive system is usually used on what type of material?
85%
The Arc voltage
Shielding the molten weld metal from atmospheric contamination
Aluminum wire

25. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
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To prevent drawing of liquid CO2 (Carbon Dioxide)
Welding process that joins metals by heating them with an electric arc
3

26. What controls the wire speed on a voltage sensing wire feeder?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Constant voltage (CV)
The Arc voltage
By there current carrying capacity

27. What 2 controls are found on a GMAW set- up?
Higher 26 to 35 arc volts
The Arc voltage
Constant- speed wire feeders and Voltage- sennsing wire feeders
Wire feed speed - Voltage control

28. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
Short- circuiting transfer - Globular transfer - Spray transfer
Motor driven generators - Transformer rectifiers - and Inverter designs
Pressure vessels and the piping industry

29. List the factors that determine the mode of metal transfer
12 to 22 arc volts
Gas metal arc welding
AWS and CSA
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

30. List 3 wire drive systems and give a short description of each
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
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
To limit the short circuiting current so that spatter is reduced

31. What 2 organizations designate specifications for GMAW wires?
Gas metal arc welding
...
AWS and CSA
3

32. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Penetration and burn - off rate of the electrode
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
...

33. What is the main purpose of 'slope'?
Pressure vessels and the piping industry
Shielding the molten weld metal from atmospheric contamination
To limit the short circuiting current so that spatter is reduced
If you dont know this check your phone

34. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
Wire feeds smoothly (yet will slip should a problem occur in the gun)
5.8 to 12.5 L/min
Motor driven generators - Transformer rectifiers - and Inverter designs

35. What does inductance control?
Constant- speed wire feeders and Voltage- sennsing wire feeders
The time rate of response for the current rise and fall
Short- circuiting transfer - Globular transfer - Spray transfer
Guns

36. With straight polarity where is 2/3 of the arc energy?
Gas metal arc welding
The negative side of a welding unit
1/4 inch to 1/2 inch
Short- circuiting transfer - Globular transfer - Spray transfer

37. What is another term for electrode holders for GMAW?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
20 to 200 times per second
Guns
Insufficient current to melt the wire off cleanly

38. What is the maximum distance that hard wire can be successfully pushed?
Short- circuiting transfer - Globular transfer - Spray transfer
15 feet (4.5 meters)
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

39. What effect does increasing and decreasing the inductance have on the weld?
Insufficient current to melt the wire off cleanly
Penetration and burn - off rate of the electrode
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Short- circuiting transfer - Globular transfer - Spray transfer

40. What type of power source is commonly used with a voltage sensing wire feeder?
Short- circuiting transfer - Globular transfer - Spray transfer
Minutes of elapsed time continually run (out of 10 minutes)
Constant current (CC)
Wire feeds smoothly (yet will slip should a problem occur in the gun)

41. 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
5.8 to 12.5 L/min
To limit the short circuiting current so that spatter is reduced
Penetration and burn - off rate of the electrode

42. What would be an indication that the drive roll pressure is adjusted correctly?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
If you dont know this check your phone
Wire feed speed - Voltage control
Wire feeds smoothly (yet will slip should a problem occur in the gun)

43. What are the 2 types of wire feeders available?
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
Constant- speed wire feeders and Voltage- sennsing wire feeders
(DCEP) Direct Current Electrode Positive or Reverse polarity

44. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
Reducing the gas source pressure to a constant working pressure
85%
Pressure vessels and the piping industry

45. What current and polarity is generally used with GMAW?
...
AWS and CSA
Gives arc voltage values to the control system of the feeder
DCEP (Direct Current Electrode Positive) Reverse Polarity

46. What power sources are used with the GMAW Process?
Welding process that joins metals by heating them with an electric arc
Motor driven generators - Transformer rectifiers - and Inverter designs
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
If you dont know this check your phone

47. What is the disadvantage of the gauge preset type of regulator/flowmeter?
1/4 inch to 1/2 inch
The Arc voltage
Motor driven generators - Transformer rectifiers - and Inverter designs
Generally not as accurate

48. What is the preferred drive roll design for solid wires?
Insufficient current to melt the wire off cleanly
National Electrical Manufactures Association
V groove or U groove
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

49. What does the wire feeder control?
3
Controls the rate of flow of a shielding gas to the gun nozzle
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Speed of the feed motor and - starting / stopping electrode feed

50. What controls amperage when using GMAW?
Controls the rate of flow of a shielding gas to the gun nozzle
Pressure vessels and the piping industry
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Wire feed speed