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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. List several industries that would use GMAW
Wire feeds smoothly (yet will slip should a problem occur in the gun)
These terms are quite restrictive and often technically incorrect
Pressure vessels and the piping industry
Generally not as accurate

2. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
Wire feed speed - Voltage control
Reducing the gas source pressure to a constant working pressure
15 feet (4.5 meters)

3. Regulators control_____________ flowmeters SHOW____________.
Insufficient current to melt the wire off cleanly
Duty cycle
Pressure - The rate of flow of a shielding gas
Welding process that joins metals by heating them with an electric arc

4. Why is the term GMAW preferred over MIG or MAG?
The time rate of response for the current rise and fall
These terms are quite restrictive and often technically incorrect
Reducing the gas source pressure to a constant working pressure
Cause flaking - which can clog the liner and contact tube

5. What output on the welding machine is used to rate the duty cycle?
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
Penetration and burn - off rate of the electrode
Minutes of elapsed time continually run (out of 10 minutes)

6. Why must CO2 cylinders be used in the vertical position?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Reducing the gas source pressure to a constant working pressure
To prevent drawing of liquid CO2 (Carbon Dioxide)
...

7. How are GMAW guns rated?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Insufficient current to melt the wire off cleanly
By there current carrying capacity
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

8. What processes are constant current (CC) power sources designed to be used with?
Speed of the feed motor and - starting / stopping electrode feed
Gives arc voltage values to the control system of the feeder
SMAW - GTAW
The negative side of a welding unit

9. What does voltage do in an electrical circuit?
Welding process that joins metals by heating them with an electric arc
Voltage is the force that overcomes resistance to allow amperage flow
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Cause flaking - which can clog the liner and contact tube

10. How many times per second does short circuiting take place?
3
The time rate of response for the current rise and fall
Short- circuiting transfer - Globular transfer - Spray transfer
20 to 200 times per second

11. What is the recommended electrode stick- out for .035 solid wire?
Reducing the gas source pressure to a constant working pressure
3
Pressure - The rate of flow of a shielding gas
1/4 inch to 1/2 inch

12. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
85%
Guns
Cause flaking - which can clog the liner and contact tube

13. Why is a fiber washer required and what cylinder gas requires it?
85%
Gives arc voltage values to the control system of the feeder
To prevent leakage - Carbon Dioxide (CO2)
1/4 inch to 1/2 inch

14. List the factors that determine the mode of metal transfer
Insufficient current to melt the wire off cleanly
Penetration and burn - off rate of the electrode
Pressure - The rate of flow of a shielding gas
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

15. What is the effect of too much slope?
Gives arc voltage values to the control system of the feeder
Insufficient current to melt the wire off cleanly
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Short- circuiting transfer - Globular transfer - Spray transfer

16. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Motor driven generators - Transformer rectifiers - and Inverter designs
Pressure vessels and the piping industry
Cause flaking - which can clog the liner and contact tube
To prevent leakage - Carbon Dioxide (CO2)

17. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
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
3

18. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Spatter problems and poor weld appearance
Constant current (CC)
Higher 26 to 35 arc volts
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

19. What 2 organizations designate specifications for GMAW wires?
AWS and CSA
Constant current (CC)
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Penetration and burn - off rate of the electrode

20. What is the required arc voltage used for short circuit transfer?
12 to 22 arc volts
The negative side of a welding unit
Constant- speed wire feeders and Voltage- sennsing wire feeders
20 to 200 times per second

21. What is an advantage of pulsed arc transfer with GMAW?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Dry ice can form within the flow control openings and cause blockage of shielding gas
Reducing the gas source pressure to a constant working pressure
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

22. What is the main purpose of 'slope'?
Constant- speed wire feeders and Voltage- sennsing wire feeders
To limit the short circuiting current so that spatter is reduced
Flux cored wires
(DCEP) Direct Current Electrode Positive or Reverse polarity

23. What effect does increasing and decreasing the inductance have on the weld?
If you dont know this check your phone
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
The negative side of a welding unit

24. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Pressure vessels and the piping industry
DCEP (Direct Current Electrode Positive) Reverse Polarity
Spatter problems and poor weld appearance
3

25. List the three methods of metal transfer with GMAW
The Arc voltage
Short- circuiting transfer - Globular transfer - Spray transfer
Wire feed speed - Voltage control
To prevent leakage - Carbon Dioxide (CO2)

26. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Spatter problems and poor weld appearance
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 or Reverse polarity
If you dont know this check your phone

27. What does the term GMAW identify?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Gas metal arc welding
Minimum distortion due to low heat input
These terms are quite restrictive and often technically incorrect

28. In the GMAW process what does voltage control?
Shielding the molten weld metal from atmospheric contamination
Puddle fluidity
Flux cored wires
Wire feed speed - Voltage control

29. What would be an indication that the drive roll pressure is adjusted correctly?
Aluminum wire
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Duty cycle

30. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Insufficient current to melt the wire off cleanly
...
Cause flaking - which can clog the liner and contact tube
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

31. What are the 2 types of wire feeders available?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Constant- speed wire feeders and Voltage- sennsing wire feeders
Controls the rate of flow of a shielding gas to the gun nozzle
AWS and CSA

32. What does a flowmeter do and what does it measure?
Controls the rate of flow of a shielding gas to the gun nozzle
85%
V groove or U groove
Generally not as accurate

33. What 2 controls are found on a GMAW set- up?
Wire feed speed - Voltage control
Puddle fluidity
Constant current (CC)
Gives arc voltage values to the control system of the feeder

34. What current and polarity is generally used with GMAW?
Gas metal arc welding
3
Constant- speed wire feeders and Voltage- sennsing wire feeders
DCEP (Direct Current Electrode Positive) Reverse Polarity

35. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
If you dont know this check your phone
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Controls the rate of flow of a shielding gas to the gun nozzle

36. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Generally not as accurate
SMAW - GTAW
85%
12 to 22 arc volts

37. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
1/4 inch to 1/2 inch
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Pressure vessels and the piping industry
Gives arc voltage values to the control system of the feeder

38. List 3 forms compressed gases may be supplied for welding
Pressure vessels and the piping industry
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
SMAW - GTAW
National Electrical Manufactures Association

39. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
Controls the rate of flow of a shielding gas to the gun nozzle
Pressure vessels and the piping industry
SMAW - GTAW

40. What controls amperage when using GMAW?
15 feet (4.5 meters)
Wire feed speed
Gives arc voltage values to the control system of the feeder
Controls the rate of flow of a shielding gas to the gun nozzle

41. What is the disadvantage of the gauge preset type of regulator/flowmeter?
To limit the short circuiting current so that spatter is reduced
Generally not as accurate
SMAW - GTAW
Constant- speed wire feeders and Voltage- sennsing wire feeders

42. What wire are knurled drive rolls most commonly used on?
Aluminum wire
Duty cycle
Dry ice can form within the flow control openings and cause blockage of shielding gas
Flux cored wires

43. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
Reducing the gas source pressure to a constant working pressure
Generally not as accurate
Dry ice can form within the flow control openings and cause blockage of shielding gas

44. Give a description of 'pinch effect'
Gas metal arc welding
AWS and CSA
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Motor driven generators - Transformer rectifiers - and Inverter designs

45. What is the preferred drive roll design for solid wires?
Welding process that joins metals by heating them with an electric arc
V groove or U groove
Pressure vessels and the piping industry
Generally not as accurate

46. Draw a typical volt amp curve for a machine that is designed for GMAW
To prevent leakage - Carbon Dioxide (CO2)
If you dont know this check your phone
Short- circuiting transfer - Globular transfer - Spray transfer
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

47. What is another term for electrode holders for GMAW?
Guns
Higher 26 to 35 arc volts
Pressure - The rate of flow of a shielding gas
Voltage is the force that overcomes resistance to allow amperage flow

48. List 3 wire drive systems and give a short description of each
Constant- speed wire feeders and Voltage- sennsing wire feeders
Minutes of elapsed time continually run (out of 10 minutes)
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

49. What is a solenoid valve and what actuates it?
The negative side of a welding unit
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Welding process that joins metals by heating them with an electric arc
SMAW - GTAW

50. What is the key advantage of short circuiting transfer?
Insufficient current to melt the wire off cleanly
AWS and CSA
Minimum distortion due to low heat input
Wire feed speed - Voltage control