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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.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

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. Why is a line heater required when using GMAW?
Shielding the molten weld metal from atmospheric contamination
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Dry ice can form within the flow control openings and cause blockage of shielding gas
Cause flaking - which can clog the liner and contact tube

2. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
...
Wire feed speed
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

3. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
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
Constant- speed wire feeders and Voltage- sennsing wire feeders
Higher 26 to 35 arc volts

4. What is the recommended electrode stick- out for .035 solid wire?
Penetration and burn - off rate of the electrode
1/4 inch to 1/2 inch
To prevent leakage - Carbon Dioxide (CO2)
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

5. What is the required arc voltage used for short circuit transfer?
12 to 22 arc volts
To limit the short circuiting current so that spatter is reduced
Short- circuiting transfer - Globular transfer - Spray transfer
(DCEP) Direct Current Electrode Positive or Reverse polarity

6. 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
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Pressure - The rate of flow of a shielding gas
Puddle fluidity

7. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
SMAW - GTAW
3
DCEP (Direct Current Electrode Positive) Reverse Polarity
Reducing the gas source pressure to a constant working pressure

8. What is another term for electrode holders for GMAW?
(DCEP) Direct Current Electrode Positive or Reverse polarity
These terms are quite restrictive and often technically incorrect
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Guns

9. What output on the welding machine is used to rate the duty cycle?
Minutes of elapsed time continually run (out of 10 minutes)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
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

10. What type of power source is commonly used with a voltage sensing wire feeder?
To prevent drawing of liquid CO2 (Carbon Dioxide)
5.8 to 12.5 L/min
Constant current (CC)
Minimum distortion due to low heat input

11. Give a brief description of the GMAW process
Insufficient current to melt the wire off cleanly
The time rate of response for the current rise and fall
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Welding process that joins metals by heating them with an electric arc

12. What does inductance control?
Shielding the molten weld metal from atmospheric contamination
Gives arc voltage values to the control system of the feeder
The time rate of response for the current rise and fall
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

13. When is the metal transferred with short circuit transfer?
When the filler wire is in direct contract with the base metal
If you dont know this check your phone
Spatter problems and poor weld appearance
The resistace to electrical current flow increases with it. Causing the electrode to heat

14. What happens when the electrode extension is increased?
These terms are quite restrictive and often technically incorrect
Reducing the gas source pressure to a constant working pressure
Shielding the molten weld metal from atmospheric contamination
The resistace to electrical current flow increases with it. Causing the electrode to heat

15. What power sources are used with the GMAW Process?
...
The time rate of response for the current rise and fall
Spatter problems and poor weld appearance
Motor driven generators - Transformer rectifiers - and Inverter designs

16. What 2 organizations designate specifications for GMAW wires?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
AWS and CSA
To limit the short circuiting current so that spatter is reduced
To prevent leakage - Carbon Dioxide (CO2)

17. What processes are constant current (CC) power sources designed to be used with?
5.8 to 12.5 L/min
SMAW - GTAW
12 to 22 arc volts
Pressure vessels and the piping industry

18. Regulators control_____________ flowmeters SHOW____________.
(DCEP) Direct Current Electrode Positive or Reverse polarity
85%
1/4 inch to 1/2 inch
Pressure - The rate of flow of a shielding gas

19. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
Generally not as accurate
Constant- speed wire feeders and Voltage- sennsing wire feeders
The Arc voltage

20. How are GMAW guns rated?
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
Cause flaking - which can clog the liner and contact tube
20 to 200 times per second

21. What is a solenoid valve and what actuates it?
By there current carrying capacity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
The resistace to electrical current flow increases with it. Causing the electrode to heat
Wire feeds smoothly (yet will slip should a problem occur in the gun)

22. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
The resistace to electrical current flow increases with it. Causing the electrode to heat
Wire feed speed
1/4 inch to 1/2 inch

23. List several industries that would use GMAW
Pressure vessels and the piping industry
Insufficient current to melt the wire off cleanly
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Minutes of elapsed time continually run (out of 10 minutes)

24. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Minutes of elapsed time continually run (out of 10 minutes)
Welding process that joins metals by heating them with an electric arc

25. 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
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
The resistace to electrical current flow increases with it. Causing the electrode to heat
Wire feed speed - Voltage control

26. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
Welding process that joins metals by heating them with an electric arc
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
The negative side of a welding unit

27. What would be an indication that the drive roll pressure is adjusted correctly?
National Electrical Manufactures Association
85%
Wire feeds smoothly (yet will slip should a problem occur in the gun)
AWS and CSA

28. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
Minutes of elapsed time continually run (out of 10 minutes)
To limit the short circuiting current so that spatter is reduced
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

29. What is an advantage of pulsed arc transfer with GMAW?
Penetration and burn - off rate of the electrode
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
Pressure vessels and the piping industry

30. What current and polarity is generally used with GMAW?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
DCEP (Direct Current Electrode Positive) Reverse Polarity
Reducing the gas source pressure to a constant working pressure
These terms are quite restrictive and often technically incorrect

31. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Dry ice can form within the flow control openings and cause blockage of shielding gas
Shielding the molten weld metal from atmospheric contamination
12 to 22 arc volts

32. List the basic equipment requirements for the GMAW process
When the filler wire is in direct contract with the base metal
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
3
Motor driven generators - Transformer rectifiers - and Inverter designs

33. What does a flowmeter do and what does it measure?
Penetration and burn - off rate of the electrode
1/4 inch to 1/2 inch
Minutes of elapsed time continually run (out of 10 minutes)
Controls the rate of flow of a shielding gas to the gun nozzle

34. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
The time rate of response for the current rise and fall
Higher 26 to 35 arc volts
Gives arc voltage values to the control system of the feeder
The Arc voltage

35. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
By there current carrying capacity
Duty cycle
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

36. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Short- circuiting transfer - Globular transfer - Spray transfer
Minutes of elapsed time continually run (out of 10 minutes)
Shielding the molten weld metal from atmospheric contamination
Generally not as accurate

37. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
National Electrical Manufactures Association
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

38. In the GMAW process what does voltage control?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Puddle fluidity
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

39. What 2 controls are found on a GMAW set- up?
Wire feed speed - Voltage control
Generally not as accurate
...
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

40. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
These terms are quite restrictive and often technically incorrect
Duty cycle
Generally not as accurate

41. What wire are knurled drive rolls most commonly used on?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Flux cored wires
Gives arc voltage values to the control system of the feeder
If you dont know this check your phone

42. What is the maximum distance that hard wire can be successfully pushed?
Speed of the feed motor and - starting / stopping electrode feed
Constant- speed wire feeders and Voltage- sennsing wire feeders
Wire feeds smoothly (yet will slip should a problem occur in the gun)
15 feet (4.5 meters)

43. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
Aluminum wire
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Controls the rate of flow of a shielding gas to the gun nozzle

44. What is the preferred drive roll design for solid wires?
V groove or U groove
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Minimum distortion due to low heat input
Penetration and burn - off rate of the electrode

45. Draw a typical volt amp curve for a machine that is designed for GMAW
DCEP (Direct Current Electrode Positive) Reverse Polarity
Reducing the gas source pressure to a constant working pressure
If you dont know this check your phone
Spatter problems and poor weld appearance

46. What does the term GMAW identify?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Shielding the molten weld metal from atmospheric contamination
Gas metal arc welding
If you dont know this check your phone

47. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Puddle fluidity
Pressure vessels and the piping industry

48. How many times per second does short circuiting take place?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Reducing the gas source pressure to a constant working pressure
20 to 200 times per second
Cause flaking - which can clog the liner and contact tube

49. What is the effect of too much slope?
1/4 inch to 1/2 inch
Constant voltage (CV)
Insufficient current to melt the wire off cleanly
Minimum distortion due to low heat input

50. In the GMAW process what does amperage control?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
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
Speed of the feed motor and - starting / stopping electrode feed