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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. A pull type drive system is usually used on what type of material?
Pressure vessels and the piping industry
Reducing the gas source pressure to a constant working pressure
Aluminum wire
Wire feed speed

2. 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
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
To limit the short circuiting current so that spatter is reduced

3. What is a typical flow rate of CO2 for short circuit transfer?
To prevent leakage - Carbon Dioxide (CO2)
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
Motor driven generators - Transformer rectifiers - and Inverter designs

4. How many times per second does short circuiting take place?
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
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

5. 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
85%
If you dont know this check your phone
Wire feeds smoothly (yet will slip should a problem occur in the gun)

6. List 3 wire drive systems and give a short description of each
Reducing the gas source pressure to a constant working pressure
1/4 inch to 1/2 inch
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

7. What controls amperage when using GMAW?
Wire feed speed - Voltage control
Wire feed speed
V groove or U groove
12 to 22 arc volts

8. What is the recommended electrode stick- out for .035 solid wire?
Welding process that joins metals by heating them with an electric arc
1/4 inch to 1/2 inch
Pressure vessels and the piping industry
Wire feed speed - Voltage control

9. What 2 organizations designate specifications for GMAW wires?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
AWS and CSA
Voltage is the force that overcomes resistance to allow amperage flow
...

10. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
National Electrical Manufactures Association
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
85%

11. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Motor driven generators - Transformer rectifiers - and Inverter designs
20 to 200 times per second

12. What are the 2 types of wire feeders available?
Controls the rate of flow of a shielding gas to the gun nozzle
Constant- speed wire feeders and Voltage- sennsing wire feeders
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

13. Regulators control_____________ flowmeters SHOW____________.
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
V groove or U groove
Pressure - The rate of flow of a shielding gas
To prevent leakage - Carbon Dioxide (CO2)

14. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
12 to 22 arc volts
Minimum distortion due to low heat input
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Cause flaking - which can clog the liner and contact tube

15. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
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Motor driven generators - Transformer rectifiers - and Inverter designs
Guns
DCEP (Direct Current Electrode Positive) Reverse Polarity

16. What happens when the electrode extension is increased?
Short- circuiting transfer - Globular transfer - Spray transfer
Speed of the feed motor and - starting / stopping electrode feed
The resistace to electrical current flow increases with it. Causing the electrode to heat
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

17. What does the abbreviation NEMA stand for?
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Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
National Electrical Manufactures Association
The Arc voltage

18. What is the key advantage of short circuiting transfer?
Generally not as accurate
Minimum distortion due to low heat input
The time rate of response for the current rise and fall
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

19. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
These terms are quite restrictive and often technically incorrect
Flux cored wires
Higher 26 to 35 arc volts
5.8 to 12.5 L/min

20. List 3 forms compressed gases may be supplied for welding
Flux cored wires
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
5.8 to 12.5 L/min
Penetration and burn - off rate of the electrode

21. Give a description of 'pinch effect'
Guns
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Pressure - The rate of flow of a shielding gas
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

22. List the factors that determine the mode of metal transfer
Short- circuiting transfer - Globular transfer - Spray transfer
Spatter problems and poor weld appearance
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Shielding the molten weld metal from atmospheric contamination

23. In the GMAW process what does amperage control?
When the filler wire is in direct contract with the base metal
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
By there current carrying capacity

24. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
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
Wire feeds smoothly (yet will slip should a problem occur in the gun)

25. In the GMAW process what does voltage control?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Spatter problems and poor weld appearance
5.8 to 12.5 L/min
Puddle fluidity

26. What is the maximum distance that hard wire can be successfully pushed?
Higher 26 to 35 arc volts
Gas metal arc welding
15 feet (4.5 meters)
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27. What is the purpose of the shielding gas used in GMAW?
15 feet (4.5 meters)
These terms are quite restrictive and often technically incorrect
Shielding the molten weld metal from atmospheric contamination
Cause flaking - which can clog the liner and contact tube

28. Why is the term GMAW preferred over MIG or MAG?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Controls the rate of flow of a shielding gas to the gun nozzle
These terms are quite restrictive and often technically incorrect
Minimum distortion due to low heat input

29. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
...
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
These terms are quite restrictive and often technically incorrect

30. What does the wire feeder control?
Guns
These terms are quite restrictive and often technically incorrect
Speed of the feed motor and - starting / stopping electrode feed
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

31. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
Voltage is the force that overcomes resistance to allow amperage flow
3
By there current carrying capacity

32. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
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
20 to 200 times per second

33. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
Short- circuiting transfer - Globular transfer - Spray transfer
(DCEP) Direct Current Electrode Positive or Reverse polarity
Higher 26 to 35 arc volts

34. What output on the welding machine is used to rate the duty cycle?
To limit the short circuiting current so that spatter is reduced
Minutes of elapsed time continually run (out of 10 minutes)
Short- circuiting transfer - Globular transfer - Spray transfer
DCEP (Direct Current Electrode Positive) Reverse Polarity

35. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Gives arc voltage values to the control system of the feeder
Penetration and burn - off rate of the electrode
National Electrical Manufactures Association
Dry ice can form within the flow control openings and cause blockage of shielding gas

36. Give a brief description of the GMAW process
Controls the rate of flow of a shielding gas to the gun nozzle
Welding process that joins metals by heating them with an electric arc
V groove or U groove
Cause flaking - which can clog the liner and contact tube

37. List the basic equipment requirements for the GMAW process
By there current carrying capacity
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
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

38. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
By there current carrying capacity
85%
DCEP (Direct Current Electrode Positive) Reverse Polarity

39. What does the term GMAW identify?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
3
Gas metal arc welding
Constant voltage (CV)

40. What is a solenoid valve and what actuates it?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Puddle fluidity
Minutes of elapsed time continually run (out of 10 minutes)
SMAW - GTAW

41. What is the disadvantage of the gauge preset type of regulator/flowmeter?
1/4 inch to 1/2 inch
The time rate of response for the current rise and fall
DCEP (Direct Current Electrode Positive) Reverse Polarity
Generally not as accurate

42. What is the main purpose of 'slope'?
Pressure - The rate of flow of a shielding gas
Voltage is the force that overcomes resistance to allow amperage flow
(DCEP) Direct Current Electrode Positive or Reverse polarity
To limit the short circuiting current so that spatter is reduced

43. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Constant current (CC)
Higher 26 to 35 arc volts
V groove or U groove

44. When is the metal transferred with short circuit transfer?
Shielding the molten weld metal from atmospheric contamination
Duty cycle
Generally not as accurate
When the filler wire is in direct contract with the base metal

45. What type of power source is commonly used with a voltage sensing wire feeder?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
To limit the short circuiting current so that spatter is reduced
Constant current (CC)
To prevent leakage - Carbon Dioxide (CO2)

46. What effect does increasing and decreasing the inductance have on the weld?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
By there current carrying capacity
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Penetration and burn - off rate of the electrode

47. How are GMAW guns rated?
Wire feed speed - Voltage control
By there current carrying capacity
Speed of the feed motor and - starting / stopping electrode feed
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

48. List several industries that would use GMAW
Constant- speed wire feeders and Voltage- sennsing wire feeders
Puddle fluidity
When the filler wire is in direct contract with the base metal
Pressure vessels and the piping industry

49. What controls the wire speed on a voltage sensing wire feeder?
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
The Arc voltage
12 to 22 arc volts
To prevent drawing of liquid CO2 (Carbon Dioxide)

50. What would be an indication that the drive roll pressure is adjusted correctly?
20 to 200 times per second
Shielding the molten weld metal from atmospheric contamination
Wire feeds smoothly (yet will slip should a problem occur in the gun)
To limit the short circuiting current so that spatter is reduced