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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?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Minutes of elapsed time continually run (out of 10 minutes)
To limit the short circuiting current so that spatter is reduced
AWS and CSA

2. Regulators control_____________ flowmeters SHOW____________.
Reducing the gas source pressure to a constant working pressure
Pressure - The rate of flow of a shielding gas
The resistace to electrical current flow increases with it. Causing the electrode to heat
DCEP (Direct Current Electrode Positive) Reverse Polarity

3. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
...
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Duty cycle

4. What 2 controls are found on a GMAW set- up?
If you dont know this check your phone
Wire feed speed - Voltage control
Higher 26 to 35 arc volts
By there current carrying capacity

5. What is the main purpose of 'slope'?
The negative side of a welding unit
Generally not as accurate
To limit the short circuiting current so that spatter is reduced
15 feet (4.5 meters)

6. Why must CO2 cylinders be used in the vertical position?
1/4 inch to 1/2 inch
V groove or U groove
Duty cycle
To prevent drawing of liquid CO2 (Carbon Dioxide)

7. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Pressure - The rate of flow of a shielding gas
Reducing the gas source pressure to a constant working pressure
85%
Flux cored wires

8. What does the wire feeder control?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Speed of the feed motor and - starting / stopping electrode feed
Cause flaking - which can clog the liner and contact tube
Short- circuiting transfer - Globular transfer - Spray transfer

9. With straight polarity where is 2/3 of the arc energy?
Pressure vessels and the piping industry
85%
The negative side of a welding unit
Cause flaking - which can clog the liner and contact tube

10. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
Gas metal arc welding
Controls the rate of flow of a shielding gas to the gun nozzle
To prevent leakage - Carbon Dioxide (CO2)

11. What controls the wire speed on a voltage sensing wire feeder?
Controls the rate of flow of a shielding gas to the gun nozzle
The Arc voltage
Shielding the molten weld metal from atmospheric contamination
To prevent drawing of liquid CO2 (Carbon Dioxide)

12. What would be an indication that the drive roll pressure is adjusted correctly?
These terms are quite restrictive and often technically incorrect
Motor driven generators - Transformer rectifiers - and Inverter designs
Minimum distortion due to low heat input
Wire feeds smoothly (yet will slip should a problem occur in the gun)

13. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
5.8 to 12.5 L/min
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
To prevent leakage - Carbon Dioxide (CO2)

14. In the GMAW process what does voltage control?
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
Puddle fluidity
Controls the rate of flow of a shielding gas to the gun nozzle

15. What is the purpose of a regulator and what does it indicate on its gauges?
To prevent leakage - Carbon Dioxide (CO2)
Minutes of elapsed time continually run (out of 10 minutes)
Reducing the gas source pressure to a constant working pressure
Short- circuiting transfer - Globular transfer - Spray transfer

16. What is another term for electrode holders for GMAW?
Controls the rate of flow of a shielding gas to the gun nozzle
Speed of the feed motor and - starting / stopping electrode feed
Guns
3

17. Draw a typical volt amp curve for a machine that is designed for GMAW
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Duty cycle
Puddle fluidity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

18. Why is a fiber washer required and what cylinder gas requires it?
Flux cored wires
Minutes of elapsed time continually run (out of 10 minutes)
Constant voltage (CV)
To prevent leakage - Carbon Dioxide (CO2)

19. What is the key advantage of short circuiting transfer?
3
Reducing the gas source pressure to a constant working pressure
Minimum distortion due to low heat input
Flux cored wires

20. List 3 wire drive systems and give a short description of each
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
1/4 inch to 1/2 inch
15 feet (4.5 meters)

21. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Voltage is the force that overcomes resistance to allow amperage flow
Minimum distortion due to low heat input
Shielding the molten weld metal from atmospheric contamination
Duty cycle

22. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
Guns
Motor driven generators - Transformer rectifiers - and Inverter designs
Speed of the feed motor and - starting / stopping electrode feed

23. What is a typical flow rate of CO2 for short circuit transfer?
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
5.8 to 12.5 L/min
The Arc voltage

24. Give a brief description of the GMAW process
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Welding process that joins metals by heating them with an electric arc
Shielding the molten weld metal from atmospheric contamination

25. List 3 forms compressed gases may be supplied for welding
Penetration and burn - off rate of the electrode
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DCEP (Direct Current Electrode Positive) Reverse Polarity
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

26. What is an advantage of pulsed arc transfer with GMAW?
Wire feed speed - Voltage control
15 feet (4.5 meters)
To limit the short circuiting current so that spatter is reduced
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

27. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
When the filler wire is in direct contract with the base metal
...
Puddle fluidity
15 feet (4.5 meters)

28. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
To prevent leakage - Carbon Dioxide (CO2)
Short- circuiting transfer - Globular transfer - Spray transfer
1/4 inch to 1/2 inch

29. 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
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Higher 26 to 35 arc volts

30. What wire are knurled drive rolls most commonly used on?
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The Arc voltage
Spatter problems and poor weld appearance
Flux cored wires

31. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
Voltage is the force that overcomes resistance to allow amperage flow
3
Minutes of elapsed time continually run (out of 10 minutes)

32. What controls amperage when using GMAW?
Minimum distortion due to low heat input
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Penetration and burn - off rate of the electrode
Wire feed speed

33. Why is a line heater required when using GMAW?
Flux cored wires
Higher 26 to 35 arc volts
Constant- speed wire feeders and Voltage- sennsing wire feeders
Dry ice can form within the flow control openings and cause blockage of shielding gas

34. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Wire feed speed
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Cause flaking - which can clog the liner and contact tube
Dry ice can form within the flow control openings and cause blockage of shielding gas

35. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
Short- circuiting transfer - Globular transfer - Spray transfer
Guns
If you dont know this check your phone

36. A pull type drive system is usually used on what type of material?
Aluminum wire
Penetration and burn - off rate of the electrode
To prevent leakage - Carbon Dioxide (CO2)
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

37. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Guns
The resistace to electrical current flow increases with it. Causing the electrode to heat
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

38. How are GMAW guns rated?
By there current carrying capacity
Cause flaking - which can clog the liner and contact tube
Short- circuiting transfer - Globular transfer - Spray transfer
(DCEP) Direct Current Electrode Positive or Reverse polarity

39. What type of power source is commonly used with a voltage sensing wire feeder?
When the filler wire is in direct contract with the base metal
The time rate of response for the current rise and fall
Wire feed speed
Constant current (CC)

40. 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
3
Wire feed speed
Voltage is the force that overcomes resistance to allow amperage flow

41. What is the recommended electrode stick- out for .035 solid wire?
Short- circuiting transfer - Globular transfer - Spray transfer
Puddle fluidity
Welding process that joins metals by heating them with an electric arc
1/4 inch to 1/2 inch

42. List several industries that would use GMAW
Minutes of elapsed time continually run (out of 10 minutes)
Aluminum wire
Pressure vessels and the piping industry
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

43. What does voltage do in an electrical circuit?
Gives arc voltage values to the control system of the feeder
These terms are quite restrictive and often technically incorrect
Voltage is the force that overcomes resistance to allow amperage flow
Wire feed speed

44. Why is the term GMAW preferred over MIG or MAG?
Higher 26 to 35 arc volts
These terms are quite restrictive and often technically incorrect
To prevent drawing of liquid CO2 (Carbon Dioxide)
Aluminum wire

45. List the basic equipment requirements for the GMAW process
Controls the rate of flow of a shielding gas to the gun nozzle
Minimum distortion due to low heat input
Cause flaking - which can clog the liner and contact tube
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

46. What is the maximum distance that hard wire can be successfully pushed?
DCEP (Direct Current Electrode Positive) Reverse Polarity
15 feet (4.5 meters)
Puddle fluidity
Aluminum wire

47. What does the term GMAW identify?
...
The time rate of response for the current rise and fall
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Gas metal arc welding

48. List the factors that determine the mode of metal transfer
Short- circuiting transfer - Globular transfer - Spray transfer
...
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

49. When is the metal transferred with short circuit transfer?
5.8 to 12.5 L/min
Wire feed speed - Voltage control
The negative side of a welding unit
When the filler wire is in direct contract with the base metal

50. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
To prevent drawing of liquid CO2 (Carbon Dioxide)
To limit the short circuiting current so that spatter is reduced
Pressure - The rate of flow of a shielding gas