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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. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
Motor driven generators - Transformer rectifiers - and Inverter designs
Gives arc voltage values to the control system of the feeder
Controls the rate of flow of a shielding gas to the gun nozzle

2. What type of power source is commonly used with a voltage sensing wire feeder?
Constant- speed wire feeders and Voltage- sennsing wire feeders
National Electrical Manufactures Association
Speed of the feed motor and - starting / stopping electrode feed
Constant current (CC)

3. What is the required arc voltage used for short circuit transfer?
To prevent drawing of liquid CO2 (Carbon Dioxide)
12 to 22 arc volts
Minutes of elapsed time continually run (out of 10 minutes)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

4. In the GMAW process what does amperage control?
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
Welding process that joins metals by heating them with an electric arc
12 to 22 arc volts

5. Draw a typical volt amp curve for a machine that is designed for GMAW
If you dont know this check your phone
Constant voltage (CV)
The time rate of response for the current rise and fall
Generally not as accurate

6. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
The negative side of a welding unit
Minutes of elapsed time continually run (out of 10 minutes)
Generally not as accurate

7. What power sources are used with the GMAW Process?
By there current carrying capacity
...
15 feet (4.5 meters)
Motor driven generators - Transformer rectifiers - and Inverter designs

8. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
SMAW - GTAW
Constant voltage (CV)
If you dont know this check your phone

9. What is a typical flow rate of CO2 for short circuit transfer?
Pressure - The rate of flow of a shielding gas
5.8 to 12.5 L/min
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Speed of the feed motor and - starting / stopping electrode feed

10. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
These terms are quite restrictive and often technically incorrect
Controls the rate of flow of a shielding gas to the gun nozzle
85%

11. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
(DCEP) Direct Current Electrode Positive or Reverse polarity
...
Pressure vessels and the piping industry
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

12. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
To prevent drawing of liquid CO2 (Carbon Dioxide)
These terms are quite restrictive and often technically incorrect
Minutes of elapsed time continually run (out of 10 minutes)
3

13. What does the abbreviation NEMA stand for?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
The resistace to electrical current flow increases with it. Causing the electrode to heat
By there current carrying capacity
National Electrical Manufactures Association

14. What current and polarity is generally used with GMAW?
Controls the rate of flow of a shielding gas to the gun nozzle
Generally not as accurate
DCEP (Direct Current Electrode Positive) Reverse Polarity
Shielding the molten weld metal from atmospheric contamination

15. Why is a line heater required when using GMAW?
The resistace to electrical current flow increases with it. Causing the electrode to heat
If you dont know this check your phone
Dry ice can form within the flow control openings and cause blockage of shielding gas
3

16. Is the arc voltage for spray transfer higher or lower than that used for short circuit 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
Higher 26 to 35 arc volts
National Electrical Manufactures Association
Shielding the molten weld metal from atmospheric contamination

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

18. What are the 2 types of wire feeders available?
Insufficient current to melt the wire off cleanly
Constant- speed wire feeders and Voltage- sennsing wire feeders
Gas metal arc welding
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. List the three methods of metal transfer with GMAW
Higher 26 to 35 arc volts
Short- circuiting transfer - Globular transfer - Spray transfer
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

20. Regulators control_____________ flowmeters SHOW____________.
Pressure - The rate of flow of a shielding gas
Motor driven generators - Transformer rectifiers - and Inverter designs
12 to 22 arc volts
The time rate of response for the current rise and fall

21. What would be an indication that the drive roll pressure is adjusted correctly?
12 to 22 arc volts
To prevent leakage - Carbon Dioxide (CO2)
The negative side of a welding unit
Wire feeds smoothly (yet will slip should a problem occur in the gun)

22. A pull type drive system is usually used on what type of material?
Aluminum wire
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
Pressure vessels and the piping industry
SMAW - GTAW

23. What is the key advantage of short circuiting transfer?
(DCEP) Direct Current Electrode Positive or Reverse polarity
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
Minimum distortion due to low heat input

24. How are GMAW guns rated?
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
Speed of the feed motor and - starting / stopping electrode feed
Wire feed speed - Voltage control

25. What is an advantage of pulsed arc transfer with GMAW?
Gas metal arc welding
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
If you dont know this check your phone

26. What controls the wire speed on a voltage sensing wire feeder?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
1/4 inch to 1/2 inch
To limit the short circuiting current so that spatter is reduced
The Arc voltage

27. 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
Cause flaking - which can clog the liner and contact tube
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

28. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
The negative side of a welding unit
3
Constant voltage (CV)
(DCEP) Direct Current Electrode Positive or Reverse polarity

29. What does the term GMAW identify?
Gas metal arc welding
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Short- circuiting transfer - Globular transfer - Spray transfer
...

30. What effect does increasing and decreasing the inductance have on the weld?
85%
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
20 to 200 times per second
AWS and CSA

31. List several industries that would use GMAW
Aluminum wire
Pressure vessels and the piping industry
3
To prevent drawing of liquid CO2 (Carbon Dioxide)

32. What wire are knurled drive rolls most commonly used on?
85%
Controls the rate of flow of a shielding gas to the gun nozzle
To prevent leakage - Carbon Dioxide (CO2)
Flux cored wires

33. What type of power source is used with a constant speed wire feeder?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Constant voltage (CV)
20 to 200 times per second
If you dont know this check your phone

34. In the GMAW process what does voltage control?
Puddle fluidity
3
Shielding the molten weld metal from atmospheric contamination
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

35. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
15 feet (4.5 meters)
Aluminum wire
85%

36. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
...
(DCEP) Direct Current Electrode Positive or Reverse polarity
Speed of the feed motor and - starting / stopping electrode feed

37. How many times per second does short circuiting take place?
Voltage is the force that overcomes resistance to allow amperage flow
20 to 200 times per second
15 feet (4.5 meters)
V groove or U groove

38. List the factors that determine the mode of metal transfer
AWS and CSA
V groove or U groove
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Constant current (CC)

39. What is the effect of too much slope?
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
Insufficient current to melt the wire off cleanly
Constant voltage (CV)

40. What 2 organizations designate specifications for GMAW wires?
Minimum distortion due to low heat input
AWS and CSA
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
The negative side of a welding unit

41. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
5.8 to 12.5 L/min
Cause flaking - which can clog the liner and contact tube
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
To limit the short circuiting current so that spatter is reduced

42. What output on the welding machine is used to rate the duty cycle?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
SMAW - GTAW
Minutes of elapsed time continually run (out of 10 minutes)
15 feet (4.5 meters)

43. What is the recommended electrode stick- out for .035 solid wire?
85%
These terms are quite restrictive and often technically incorrect
15 feet (4.5 meters)
1/4 inch to 1/2 inch

44. What 2 controls are found on a GMAW set- up?
These terms are quite restrictive and often technically incorrect
When the filler wire is in direct contract with the base metal
Wire feed speed - Voltage control
Guns

45. 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
Reducing the gas source pressure to a constant working pressure
To limit the short circuiting current so that spatter is reduced

46. What happens when the electrode extension is increased?
Pressure vessels and the piping industry
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
The resistace to electrical current flow increases with it. Causing the electrode to heat

47. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Insufficient current to melt the wire off cleanly
Duty cycle
Wire feed speed - Voltage control
Short- circuiting transfer - Globular transfer - Spray transfer

48. What processes are constant current (CC) power sources designed to be used with?
Puddle fluidity
National Electrical Manufactures Association
SMAW - GTAW
Reducing the gas source pressure to a constant working pressure

49. What is the purpose of a regulator and what does it indicate on its gauges?
If you dont know this check your phone
Reducing the gas source pressure to a constant working pressure
Controls the rate of flow of a shielding gas to the gun nozzle
DCEP (Direct Current Electrode Positive) Reverse Polarity

50. What is the maximum distance that hard wire can be successfully pushed?
15 feet (4.5 meters)
(DCEP) Direct Current Electrode Positive or Reverse polarity
Shielding the molten weld metal from atmospheric contamination
Minutes of elapsed time continually run (out of 10 minutes)