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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 minimum % value of argon that must be present to use the spray transfer method of GMAW?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
85%
Aluminum wire
To prevent drawing of liquid CO2 (Carbon Dioxide)

2. How are GMAW guns rated?
AWS and CSA
When the filler wire is in direct contract with the base metal
By there current carrying capacity
1/4 inch to 1/2 inch

3. What are the 2 types of wire feeders available?
The negative side of a welding unit
To limit the short circuiting current so that spatter is reduced
Constant- speed wire feeders and Voltage- sennsing wire feeders
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

4. 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
National Electrical Manufactures Association
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
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5. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
5.8 to 12.5 L/min
Aluminum wire
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

6. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
Aluminum wire
The time rate of response for the current rise and fall
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

7. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Insufficient current to melt the wire off cleanly
Speed of the feed motor and - starting / stopping electrode feed
Cause flaking - which can clog the liner and contact tube
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8. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Short- circuiting transfer - Globular transfer - Spray transfer
Guns

9. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
Constant voltage (CV)
Duty cycle
Speed of the feed motor and - starting / stopping electrode feed

10. What does inductance control?
Guns
When the filler wire is in direct contract with the base metal
Aluminum wire
The time rate of response for the current rise and fall

11. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
3
...
AWS and CSA
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

12. What 2 controls are found on a GMAW set- up?
20 to 200 times per second
Wire feed speed - Voltage control
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Welding process that joins metals by heating them with an electric arc

13. What is the effect of too much slope?
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
85%
Insufficient current to melt the wire off cleanly

14. What is another term for electrode holders for GMAW?
Guns
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
DCEP (Direct Current Electrode Positive) Reverse Polarity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

15. What effect does increasing and decreasing the inductance have on the weld?
Minimum distortion due to low heat input
Voltage is the force that overcomes resistance to allow amperage flow
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 - Voltage control

16. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Guns
Constant current (CC)

17. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Puddle fluidity
Minutes of elapsed time continually run (out of 10 minutes)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Gives arc voltage values to the control system of the feeder

18. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
AWS and CSA
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Dry ice can form within the flow control openings and cause blockage of shielding gas

19. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Constant current (CC)
...
These terms are quite restrictive and often technically incorrect

20. A pull type drive system is usually used on what type of material?
When the filler wire is in direct contract with the base metal
Puddle fluidity
If you dont know this check your phone
Aluminum wire

21. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Speed of the feed motor and - starting / stopping electrode feed
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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

22. What is the purpose of a regulator and what does it indicate on its gauges?
Short- circuiting transfer - Globular transfer - Spray transfer
Duty cycle
3
Reducing the gas source pressure to a constant working pressure

23. List the factors that determine the mode of metal transfer
Short- circuiting transfer - Globular transfer - Spray transfer
Shielding the molten weld metal from atmospheric contamination
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Minimum distortion due to low heat input

24. List several industries that would use GMAW
Shielding the molten weld metal from atmospheric contamination
DCEP (Direct Current Electrode Positive) Reverse Polarity
Pressure vessels and the piping industry
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

25. What type of power source is commonly used with a voltage sensing wire feeder?
Shielding the molten weld metal from atmospheric contamination
Constant current (CC)
1/4 inch to 1/2 inch
If you dont know this check your phone

26. What is an advantage of pulsed arc transfer 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
...
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
SMAW - GTAW

27. What does the term GMAW identify?
Spatter problems and poor weld appearance
Pressure vessels and the piping industry
Voltage is the force that overcomes resistance to allow amperage flow
Gas metal arc welding

28. What is the preferred drive roll design for solid wires?
Pressure - The rate of flow of a shielding gas
(DCEP) Direct Current Electrode Positive or Reverse polarity
V groove or U groove
The resistace to electrical current flow increases with it. Causing the electrode to heat

29. Draw a typical volt amp curve for a machine that is designed for GMAW
If you dont know this check your phone
Cause flaking - which can clog the liner and contact tube
Puddle fluidity
Pressure - The rate of flow of a shielding gas

30. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
By there current carrying capacity
Wire feeds smoothly (yet will slip should a problem occur in the gun)
85%

31. What does voltage do in an electrical circuit?
AWS and CSA
To limit the short circuiting current so that spatter is reduced
Constant- speed wire feeders and Voltage- sennsing wire feeders
Voltage is the force that overcomes resistance to allow amperage flow

32. What is a typical flow rate of CO2 for short circuit transfer?
These terms are quite restrictive and often technically incorrect
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
Flux cored wires
5.8 to 12.5 L/min

33. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Welding process that joins metals by heating them with an electric arc
3
Pressure - The rate of flow of a shielding gas
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

34. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Generally not as accurate
Speed of the feed motor and - starting / stopping electrode feed

35. When is the metal transferred with short circuit transfer?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
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
When the filler wire is in direct contract with the base metal

36. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Generally not as accurate
3
Insufficient current to melt the wire off cleanly

37. What is the purpose of the shielding gas used in GMAW?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
85%
Shielding the molten weld metal from atmospheric contamination
Penetration and burn - off rate of the electrode

38. What happens when the electrode extension is increased?
Pressure - The rate of flow of a shielding gas
The resistace to electrical current flow increases with it. Causing the electrode to heat
5.8 to 12.5 L/min
Spatter problems and poor weld appearance

39. With straight polarity where is 2/3 of the arc energy?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
The negative side of a welding unit
Higher 26 to 35 arc volts
20 to 200 times per second

40. How many times per second does short circuiting take place?
20 to 200 times per second
Wire feed speed - Voltage control
3
15 feet (4.5 meters)

41. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Minimum distortion due to low heat input
The negative side of a welding unit
Controls the rate of flow of a shielding gas to the gun nozzle
Duty cycle

42. What does the wire feeder control?
Pressure vessels and the piping industry
Controls the rate of flow of a shielding gas to the gun nozzle
Speed of the feed motor and - starting / stopping electrode feed
20 to 200 times per second

43. In the GMAW process what does amperage control?
To prevent leakage - Carbon Dioxide (CO2)
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Penetration and burn - off rate of the electrode
Pressure - The rate of flow of a shielding gas

44. In the GMAW process what does voltage control?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Gives arc voltage values to the control system of the feeder
Puddle fluidity
Guns

45. What wire are knurled drive rolls most commonly used on?
3
Motor driven generators - Transformer rectifiers - and Inverter designs
Flux cored wires
To prevent drawing of liquid CO2 (Carbon Dioxide)

46. What 2 organizations designate specifications for GMAW wires?
When the filler wire is in direct contract with the base metal
Insufficient current to melt the wire off cleanly
DCEP (Direct Current Electrode Positive) Reverse Polarity
AWS and CSA

47. List the three methods of metal transfer with GMAW
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Reducing the gas source pressure to a constant working pressure
These terms are quite restrictive and often technically incorrect
Short- circuiting transfer - Globular transfer - Spray transfer

48. Why is a fiber washer required and what cylinder gas requires it?
Gas metal arc welding
Wire feed speed - Voltage control
To prevent leakage - Carbon Dioxide (CO2)
Speed of the feed motor and - starting / stopping electrode feed

49. What would be an indication that the drive roll pressure is adjusted correctly?
Minimum distortion due to low heat input
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Spatter problems and poor weld appearance
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

50. What is the required arc voltage used for short circuit transfer?
If you dont know this check your phone
12 to 22 arc volts
Aluminum wire
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun