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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. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
By there current carrying capacity
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
Cause flaking - which can clog the liner and contact tube

2. What processes are constant current (CC) power sources designed to be used with?
Gas metal arc welding
SMAW - GTAW
AWS and CSA
Insufficient current to melt the wire off cleanly

3. List 3 forms compressed gases may be supplied for welding
To prevent drawing of liquid CO2 (Carbon Dioxide)
15 feet (4.5 meters)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Constant voltage (CV)

4. How many times per second does short circuiting take place?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
20 to 200 times per second
Higher 26 to 35 arc volts
Wire feeds smoothly (yet will slip should a problem occur in the gun)

5. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
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
If you dont know this check your phone

6. What does the wire feeder control?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
The Arc voltage
Speed of the feed motor and - starting / stopping electrode feed
Duty cycle

7. List the basic equipment requirements for the GMAW process
...
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
To prevent drawing of liquid CO2 (Carbon Dioxide)
Wire feeds smoothly (yet will slip should a problem occur in the gun)

8. List the factors that determine the mode of metal transfer
The resistace to electrical current flow increases with it. Causing the electrode to heat
To limit the short circuiting current so that spatter is reduced
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Wire feed speed

9. What 2 controls are found on a GMAW set- up?
Wire feed speed - 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
Spatter problems and poor weld appearance
Flux cored wires

10. What is the purpose of a regulator and what does it indicate on its gauges?
Gas metal arc welding
Constant current (CC)
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Reducing the gas source pressure to a constant working pressure

11. What is an advantage of pulsed arc transfer with GMAW?
Duty cycle
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Pressure vessels and the piping industry
Generally not as accurate

12. What current and polarity is generally used with GMAW?
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Flux cored wires
DCEP (Direct Current Electrode Positive) Reverse Polarity
Constant current (CC)

13. Why is a fiber washer required and what cylinder gas requires it?
V groove or U groove
To prevent leakage - Carbon Dioxide (CO2)
Controls the rate of flow of a shielding gas to the gun nozzle
Cause flaking - which can clog the liner and contact tube

14. What is the maximum distance that hard wire can be successfully pushed?
Constant- speed wire feeders and Voltage- sennsing wire feeders
15 feet (4.5 meters)
20 to 200 times per second
Voltage is the force that overcomes resistance to allow amperage flow

15. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
When the filler wire is in direct contract with the base metal
Higher 26 to 35 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
To prevent drawing of liquid CO2 (Carbon Dioxide)

16. Why is a line heater required when using GMAW?
Short- circuiting transfer - Globular transfer - Spray transfer
Dry ice can form within the flow control openings and cause blockage of shielding gas
(DCEP) Direct Current Electrode Positive or Reverse polarity
Higher 26 to 35 arc volts

17. List the three methods of metal transfer with GMAW
Welding process that joins metals by heating them with an electric arc
Wire feed speed
Short- circuiting transfer - Globular transfer - Spray transfer
To limit the short circuiting current so that spatter is reduced

18. Regulators control_____________ flowmeters SHOW____________.
Gas metal arc welding
Pressure - The rate of flow of a shielding gas
3
Minimum distortion due to low heat input

19. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Voltage is the force that overcomes resistance to allow amperage flow
Generally not as accurate
3
Duty cycle

20. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Minutes of elapsed time continually run (out of 10 minutes)
Short- circuiting transfer - Globular transfer - Spray transfer
Dry ice can form within the flow control openings and cause blockage of shielding gas
85%

21. In the GMAW process what does amperage control?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Constant- speed wire feeders and Voltage- sennsing wire feeders
Penetration and burn - off rate of the electrode

22. What does inductance control?
Pressure vessels and the piping industry
The time rate of response for the current rise and fall
These terms are quite restrictive and often technically incorrect
Aluminum wire

23. List 3 wire drive systems and give a short description of each
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
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Insufficient current to melt the wire off cleanly
SMAW - GTAW

24. What is the purpose of the shielding gas used in GMAW?
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
Shielding the molten weld metal from atmospheric contamination
Pressure - The rate of flow of a shielding gas

25. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
V groove or U groove
3
Gives arc voltage values to the control system of the feeder

26. Draw a typical volt amp curve for a machine that is designed for GMAW
To limit the short circuiting current so that spatter is reduced
If you dont know this check your phone
By there current carrying capacity
Dry ice can form within the flow control openings and cause blockage of shielding gas

27. What does a flowmeter do and what does it measure?
Motor driven generators - Transformer rectifiers - and Inverter designs
Constant current (CC)
Constant voltage (CV)
Controls the rate of flow of a shielding gas to the gun nozzle

28. What is another term for electrode holders for GMAW?
Guns
If you dont know this check your phone
Wire feed speed - Voltage control
Minutes of elapsed time continually run (out of 10 minutes)

29. What is the effect of too much slope?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
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
Penetration and burn - off rate of the electrode
Insufficient current to melt the wire off cleanly

30. What does the term GMAW identify?
Higher 26 to 35 arc volts
(DCEP) Direct Current Electrode Positive or Reverse polarity
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

31. What would be an indication that the drive roll pressure is adjusted correctly?
The time rate of response for the current rise and fall
To prevent drawing of liquid CO2 (Carbon Dioxide)
DCEP (Direct Current Electrode Positive) Reverse Polarity
Wire feeds smoothly (yet will slip should a problem occur in the gun)

32. How are GMAW guns rated?
By there current carrying capacity
Motor driven generators - Transformer rectifiers - and Inverter designs
3
The resistace to electrical current flow increases with it. Causing the electrode to heat

33. What 2 organizations designate specifications for GMAW wires?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Minutes of elapsed time continually run (out of 10 minutes)
(DCEP) Direct Current Electrode Positive or Reverse polarity
AWS and CSA

34. What effect does increasing and decreasing the inductance have on the weld?
National Electrical Manufactures Association
Constant- speed wire feeders and Voltage- sennsing wire feeders
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Constant voltage (CV)

35. Give a brief description of the GMAW process
1/4 inch to 1/2 inch
Gas metal arc welding
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Welding process that joins metals by heating them with an electric arc

36. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
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
Minutes of elapsed time continually run (out of 10 minutes)
If you dont know this check your phone

37. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
If you dont know this check your phone
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Dry ice can form within the flow control openings and cause blockage of shielding gas

38. When is the metal transferred with short circuit transfer?
When the filler wire is in direct contract with the base metal
Motor driven generators - Transformer rectifiers - and Inverter designs
Constant current (CC)
Flux cored wires

39. What controls the wire speed on a voltage sensing wire feeder?
Generally not as accurate
Higher 26 to 35 arc volts
The Arc voltage
When the filler wire is in direct contract with the base metal

40. What output on the welding machine is used to rate the duty cycle?
By there current carrying capacity
To prevent leakage - Carbon Dioxide (CO2)
If you dont know this check your phone
Minutes of elapsed time continually run (out of 10 minutes)

41. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
If you dont know this check your phone
Cause flaking - which can clog the liner and contact tube
Aluminum wire

42. What controls amperage when using GMAW?
Flux cored wires
The Arc voltage
Wire feed speed
The resistace to electrical current flow increases with it. Causing the electrode to heat

43. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Short- circuiting transfer - Globular transfer - Spray transfer
Higher 26 to 35 arc volts
...
Generally not as accurate

44. What wire are knurled drive rolls most commonly used on?
12 to 22 arc volts
Flux cored wires
Gives arc voltage values to the control system of the feeder
Cause flaking - which can clog the liner and contact tube

45. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
Flux cored wires
Reducing the gas source pressure to a constant working pressure
1/4 inch to 1/2 inch

46. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
The negative side of a welding unit
If you dont know this check your phone
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

47. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
The resistace to electrical current flow increases with it. Causing the electrode to heat
...
Cause flaking - which can clog the liner and contact tube
Wire feed speed - Voltage control

48. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Gas metal arc welding
Minimum distortion due to low heat input

49. What power sources are used with the GMAW Process?
National Electrical Manufactures Association
85%
Motor driven generators - Transformer rectifiers - and Inverter designs
Gas metal arc welding

50. Why is globular transfer generally avoided with GMAW?
Wire feed speed
Pressure - The rate of flow of a shielding gas
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Spatter problems and poor weld appearance