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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 is the metal transferred with short circuit transfer?
These terms are quite restrictive and often technically incorrect
When the filler wire is in direct contract with the base metal
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

2. List the factors that determine the mode of metal transfer
Motor driven generators - Transformer rectifiers - and Inverter designs
Higher 26 to 35 arc volts
Minutes of elapsed time continually run (out of 10 minutes)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

3. What is the disadvantage of the gauge preset type of regulator/flowmeter?
AWS and CSA
Duty cycle
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Generally not as accurate

4. What does the abbreviation NEMA stand for?
Controls the rate of flow of a shielding gas to the gun nozzle
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
15 feet (4.5 meters)
National Electrical Manufactures Association

5. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
Wire feed speed
Cause flaking - which can clog the liner and contact tube
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

6. What is an advantage of pulsed arc transfer with GMAW?
3
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Constant current (CC)

7. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
(DCEP) Direct Current Electrode Positive or Reverse polarity
1/4 inch to 1/2 inch
National Electrical Manufactures Association

8. What is the key advantage of short circuiting transfer?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
20 to 200 times per second
Minimum distortion due to low heat input

9. What wire are knurled drive rolls most commonly used on?
Gas metal arc welding
Flux cored wires
Pressure - The rate of flow of a shielding gas
Short- circuiting transfer - Globular transfer - Spray transfer

10. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Welding process that joins metals by heating them with an electric arc
Duty cycle
The negative side of a welding unit
National Electrical Manufactures Association

11. What effect does increasing and decreasing the inductance have on the weld?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
When the filler wire is in direct contract with the base metal
Duty cycle

12. In the GMAW process what does voltage control?
12 to 22 arc volts
Higher 26 to 35 arc volts
Puddle fluidity
Motor driven generators - Transformer rectifiers - and Inverter designs

13. What is the required arc voltage used for short circuit transfer?
5.8 to 12.5 L/min
Motor driven generators - Transformer rectifiers - and Inverter designs
12 to 22 arc volts
Wire feed speed - Voltage control

14. Regulators control_____________ flowmeters SHOW____________.
Dry ice can form within the flow control openings and cause blockage of shielding gas
Pressure - The rate of flow of a shielding gas
National Electrical Manufactures Association
These terms are quite restrictive and often technically incorrect

15. What is the main purpose of 'slope'?
Insufficient current to melt the wire off cleanly
To limit the short circuiting current so that spatter is reduced
Aluminum wire
(DCEP) Direct Current Electrode Positive or Reverse polarity

16. What is a solenoid valve and what actuates it?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
If you dont know this check your phone
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Voltage is the force that overcomes resistance to allow amperage flow

17. Draw a typical volt amp curve for a machine that is designed for GMAW
If you dont know this check your phone
Short- circuiting transfer - Globular transfer - Spray transfer
SMAW - GTAW
To prevent leakage - Carbon Dioxide (CO2)

18. What 2 organizations designate specifications for GMAW wires?
AWS and CSA
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Puddle fluidity
If you dont know this check your phone

19. Give a description of 'pinch effect'
Reducing the gas source pressure to a constant working pressure
Motor driven generators - Transformer rectifiers - and Inverter designs
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

20. What is the purpose of the shielding gas used in GMAW?
Spatter problems and poor weld appearance
If you dont know this check your phone
When the filler wire is in direct contract with the base metal
Shielding the molten weld metal from atmospheric contamination

21. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Pressure - The rate of flow of a shielding gas
AWS and CSA
...
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

22. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Reducing the gas source pressure to a constant working pressure
Gives arc voltage values to the control system of the feeder
Penetration and burn - off rate of the electrode
Aluminum wire

23. What type of power source is used with a constant speed wire feeder?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Guns
Constant voltage (CV)
Welding process that joins metals by heating them with an electric arc

24. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
Higher 26 to 35 arc volts
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

25. In the GMAW process what does amperage control?
Pressure vessels and the piping industry
3
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

26. Why is a line heater required when using GMAW?
Speed of the feed motor and - starting / stopping electrode feed
Dry ice can form within the flow control openings and cause blockage of shielding gas
Higher 26 to 35 arc volts
Constant current (CC)

27. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Welding process that joins metals by heating them with an electric arc
3
Shielding the molten weld metal from atmospheric contamination
Gives arc voltage values to the control system of the feeder

28. What is the maximum distance that hard wire can be successfully pushed?
15 feet (4.5 meters)
Welding process that joins metals by heating them with an electric arc
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Wire feed speed - Voltage control

29. Give a brief description of the GMAW process
By there current carrying capacity
Welding process that joins metals by heating them with an electric arc
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
1/4 inch to 1/2 inch

30. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
Constant current (CC)
To prevent leakage - Carbon Dioxide (CO2)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

31. What does the wire feeder control?
Short- circuiting transfer - Globular transfer - Spray transfer
National Electrical Manufactures Association
Speed of the feed motor and - starting / stopping electrode feed
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

32. What is the purpose of a regulator and what does it indicate on its gauges?
12 to 22 arc volts
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 limit the short circuiting current so that spatter is reduced

33. What would be an indication that the drive roll pressure is adjusted correctly?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
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

34. What is another term for electrode holders for GMAW?
Gives arc voltage values to the control system of the feeder
Guns
Constant- speed wire feeders and Voltage- sennsing wire feeders
AWS and CSA

35. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
(DCEP) Direct Current Electrode Positive or Reverse polarity
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
The resistace to electrical current flow increases with it. Causing the electrode to heat

36. How many times per second does short circuiting take place?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
20 to 200 times per second
Minimum distortion due to low heat input
The Arc voltage

37. What output on the welding machine is used to rate the duty cycle?
85%
Minutes of elapsed time continually run (out of 10 minutes)
Motor driven generators - Transformer rectifiers - and Inverter designs
Guns

38. List 3 forms compressed gases may be supplied for welding
Shielding the molten weld metal from atmospheric contamination
Minutes of elapsed time continually run (out of 10 minutes)
Pressure vessels and the piping industry
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

39. What are the 2 types of wire feeders available?
Gives arc voltage values to the control system of the feeder
Constant- speed wire feeders and Voltage- sennsing wire feeders
SMAW - GTAW
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

40. What is the preferred drive roll design for solid wires?
Aluminum wire
Gas metal arc welding
V groove or U groove
To prevent leakage - Carbon Dioxide (CO2)

41. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
Speed of the feed motor and - starting / stopping electrode feed
Minutes of elapsed time continually run (out of 10 minutes)
15 feet (4.5 meters)

42. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
12 to 22 arc volts
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
When the filler wire is in direct contract with the base metal

43. With straight polarity where is 2/3 of the arc energy?
AWS and CSA
The negative side of a welding unit
Welding process that joins metals by heating them with an electric arc
The resistace to electrical current flow increases with it. Causing the electrode to heat

44. List several industries that would use GMAW
Higher 26 to 35 arc volts
Speed of the feed motor and - starting / stopping electrode feed
Pressure vessels and the piping industry
3

45. 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
To prevent leakage - Carbon Dioxide (CO2)
15 feet (4.5 meters)

46. What is a typical flow rate of CO2 for short circuit transfer?
20 to 200 times per second
Minimum distortion due to low heat input
5.8 to 12.5 L/min
15 feet (4.5 meters)

47. Why must CO2 cylinders be used in the vertical position?
SMAW - GTAW
To prevent drawing of liquid CO2 (Carbon Dioxide)
Minutes of elapsed time continually run (out of 10 minutes)
Insufficient current to melt the wire off cleanly

48. What 2 controls are found on a GMAW set- up?
Cause flaking - which can clog the liner and contact tube
Minimum distortion due to low heat input
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Wire feed speed - Voltage control

49. What type of power source is commonly used with a voltage sensing wire feeder?
85%
Constant current (CC)
Gives arc voltage values to the control system of the feeder
Controls the rate of flow of a shielding gas to the gun nozzle

50. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
(DCEP) Direct Current Electrode Positive or Reverse polarity
Dry ice can form within the flow control openings and cause blockage of shielding gas
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze