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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. What controls the wire speed on a voltage sensing wire feeder?
Insufficient current to melt the wire off cleanly
To limit the short circuiting current so that spatter is reduced
The Arc voltage
(DCEP) Direct Current Electrode Positive or Reverse polarity

2. What is the maximum distance that hard wire can be successfully pushed?
3
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
15 feet (4.5 meters)

3. Why is the term GMAW preferred over MIG or MAG?
Reducing the gas source pressure to a constant working pressure
By there current carrying capacity
Speed of the feed motor and - starting / stopping electrode feed
These terms are quite restrictive and often technically incorrect

4. What 2 controls are found on a GMAW set- up?
To limit the short circuiting current so that spatter is reduced
Pressure - The rate of flow of a shielding gas
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Wire feed speed - Voltage control

5. Why is globular transfer generally avoided with GMAW?
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Short- circuiting transfer - Globular transfer - Spray transfer
These terms are quite restrictive and often technically incorrect
Spatter problems and poor weld appearance

6. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
DCEP (Direct Current Electrode Positive) Reverse Polarity
Pressure - The rate of flow of a shielding gas
5.8 to 12.5 L/min

7. What type of power source is used with a constant speed wire feeder?
By there current carrying capacity
Guns
DCEP (Direct Current Electrode Positive) Reverse Polarity
Constant voltage (CV)

8. What is the preferred drive roll design for solid wires?
V groove or U groove
3
Voltage is the force that overcomes resistance to allow amperage flow
85%

9. How many times per second does short circuiting take place?
12 to 22 arc volts
1/4 inch to 1/2 inch
Constant current (CC)
20 to 200 times per second

10. List the three methods of metal transfer with 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
Wire feeds smoothly (yet will slip should a problem occur in the gun)
(DCEP) Direct Current Electrode Positive or Reverse polarity
Short- circuiting transfer - Globular transfer - Spray transfer

11. What is a typical flow rate of CO2 for short circuit transfer?
Voltage is the force that overcomes resistance to allow amperage flow
5.8 to 12.5 L/min
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
85%

12. A pull type drive system is usually used on what type of material?
Aluminum wire
The Arc voltage
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Penetration and burn - off rate of the electrode

13. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Puddle fluidity
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Pressure vessels and the piping industry

14. What effect does increasing and decreasing the inductance have on the weld?
Cause flaking - which can clog the liner and contact tube
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 current (CC)
These terms are quite restrictive and often technically incorrect

15. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Insufficient current to melt the wire off cleanly
20 to 200 times per second
Flux cored wires
3

16. What would be an indication that the drive roll pressure is adjusted correctly?
Shielding the molten weld metal from atmospheric contamination
85%
Wire feeds smoothly (yet will slip should a problem occur in the gun)
If you dont know this check your phone

17. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
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
Higher 26 to 35 arc volts

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

19. List the basic equipment requirements for the GMAW process
Gas metal arc welding
Penetration and burn - off rate of the electrode
Voltage is the force that overcomes resistance to allow amperage flow
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

20. List 3 forms compressed gases may be supplied for welding
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Penetration and burn - off rate of the electrode
85%
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

21. 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
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Constant voltage (CV)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

22. What is the main purpose of 'slope'?
15 feet (4.5 meters)
Reducing the gas source pressure to a constant working pressure
Spatter problems and poor weld appearance
To limit the short circuiting current so that spatter is reduced

23. In the GMAW process what does amperage control?
20 to 200 times per second
Penetration and burn - off rate of the electrode
The resistace to electrical current flow increases with it. Causing the electrode to heat
Short- circuiting transfer - Globular transfer - Spray transfer

24. A 10 minute cycle of welding time vs cooling time a given machine can handle.
...
Wire feed speed
Speed of the feed motor and - starting / stopping electrode feed
Duty cycle

25. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
...
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Guns
Speed of the feed motor and - starting / stopping electrode feed

26. In the GMAW process what does voltage control?
Constant current (CC)
AWS and CSA
The Arc voltage
Puddle fluidity

27. With straight polarity where is 2/3 of the arc energy?
85%
The negative side of a welding unit
Wire feed speed - Voltage control
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

28. What 2 organizations designate specifications for GMAW wires?
Welding process that joins metals by heating them with an electric arc
AWS and CSA
V groove or U groove
1/4 inch to 1/2 inch

29. What type of power source is commonly used with a voltage sensing wire feeder?
Higher 26 to 35 arc volts
Constant current (CC)
National Electrical Manufactures Association
Dry ice can form within the flow control openings and cause blockage of shielding gas

30. Give a description of 'pinch effect'
15 feet (4.5 meters)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Duty cycle

31. What is another term for electrode holders for GMAW?
By there current carrying capacity
Gas metal arc welding
AWS and CSA
Guns

32. Why is a fiber washer required and what cylinder gas requires it?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
To prevent leakage - Carbon Dioxide (CO2)
Generally not as accurate
These terms are quite restrictive and often technically incorrect

33. 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
Motor driven generators - Transformer rectifiers - and Inverter designs
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
SMAW - GTAW

34. What wire are knurled drive rolls most commonly used on?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Flux cored wires
Welding process that joins metals by heating them with an electric arc
Controls the rate of flow of a shielding gas to the gun nozzle

35. What is the effect of too much slope?
15 feet (4.5 meters)
Insufficient current to melt the wire off cleanly
...
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

36. What does inductance control?
The negative side of a welding unit
Voltage is the force that overcomes resistance to allow amperage flow
The time rate of response for the current rise and fall
To prevent leakage - Carbon Dioxide (CO2)

37. What is an advantage of pulsed arc transfer with GMAW?
(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
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

38. List the factors that determine the mode of metal transfer
Higher 26 to 35 arc volts
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

39. When is the metal transferred with short circuit transfer?
Constant voltage (CV)
AWS and CSA
When the filler wire is in direct contract with the base metal
To limit the short circuiting current so that spatter is reduced

40. What does voltage do in an electrical circuit?
5.8 to 12.5 L/min
The Arc voltage
By there current carrying capacity
Voltage is the force that overcomes resistance to allow amperage flow

41. What is the required arc voltage used for short circuit transfer?
12 to 22 arc volts
National Electrical Manufactures Association
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Controls the rate of flow of a shielding gas to the gun nozzle

42. 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)
Flux cored wires
85%
National Electrical Manufactures Association

43. What is a solenoid valve and what actuates it?
Short- circuiting transfer - Globular transfer - Spray transfer
DCEP (Direct Current Electrode Positive) Reverse Polarity
Insufficient current to melt the wire off cleanly
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

44. What does the wire feeder control?
5.8 to 12.5 L/min
Speed of the feed motor and - starting / stopping electrode feed
Gas metal arc welding
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

45. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Gives arc voltage values to the control system of the feeder
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on 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
V groove or U groove

46. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
National Electrical Manufactures Association

47. What happens when the electrode extension is increased?
When the filler wire is in direct contract with the base metal
The resistace to electrical current flow increases with it. Causing the electrode to heat
Constant current (CC)
Gas metal arc welding

48. What are the 2 types of wire feeders available?
Spatter problems and poor weld appearance
When the filler wire is in direct contract with the base metal
Wire feed speed - Voltage control
Constant- speed wire feeders and Voltage- sennsing wire feeders

49. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Duty cycle
Guns
To limit the short circuiting current so that spatter is reduced
If you dont know this check your phone

50. What does a flowmeter do and what does it measure?
Guns
Pressure - The rate of flow of a shielding gas
Controls the rate of flow of a shielding gas to the gun nozzle
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field