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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. What is the required arc voltage used for short circuit transfer?
Shielding the molten weld metal from atmospheric contamination
12 to 22 arc volts
The Arc voltage
By there current carrying capacity

2. Why is a line heater required when using GMAW?
Minimum distortion due to low heat input
Insufficient current to melt the wire off cleanly
Pressure - The rate of flow of a shielding gas
Dry ice can form within the flow control openings and cause blockage of shielding gas

3. Give a brief description of the GMAW process
...
1/4 inch to 1/2 inch
V groove or U groove
Welding process that joins metals by heating them with an electric arc

4. Why must CO2 cylinders be used in the vertical position?
Constant current (CC)
National Electrical Manufactures Association
These terms are quite restrictive and often technically incorrect
To prevent drawing of liquid CO2 (Carbon Dioxide)

5. What is the preferred drive roll design for solid 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
Puddle fluidity
Aluminum wire
V groove or U groove

6. List 3 wire drive systems and give a short description of each
Penetration and burn - off rate of the electrode
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
3
These terms are quite restrictive and often technically incorrect

7. How are GMAW guns rated?
By there current carrying capacity
The negative side of a welding unit
Pressure - The rate of flow of a shielding gas
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

8. What 2 organizations designate specifications for GMAW wires?
Constant voltage (CV)
Wire feeds smoothly (yet will slip should a problem occur in the gun)
AWS and CSA
Cause flaking - which can clog the liner and contact tube

9. When is the metal transferred with short circuit transfer?
Insufficient current to melt the wire off cleanly
5.8 to 12.5 L/min
When the filler wire is in direct contract with the base metal
20 to 200 times per second

10. Why is the term GMAW preferred over MIG or MAG?
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Guns
These terms are quite restrictive and often technically incorrect
The negative side of a welding unit

11. What wire are knurled drive rolls most commonly used on?
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(DCEP) Direct Current Electrode Positive or Reverse polarity
DCEP (Direct Current Electrode Positive) Reverse Polarity
Flux cored wires

12. What is an advantage of pulsed arc transfer with GMAW?
Duty cycle
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
85%
These terms are quite restrictive and often technically incorrect

13. List several industries that would use GMAW
Penetration and burn - off rate of the electrode
Dry ice can form within the flow control openings and cause blockage of shielding gas
Pressure vessels and the piping industry
To limit the short circuiting current so that spatter is reduced

14. What does the term GMAW identify?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Gas metal arc welding
When the filler wire is in direct contract with the base metal
Generally not as accurate

15. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
SMAW - GTAW
Pressure vessels and the piping industry
Welding process that joins metals by heating them with an electric arc
85%

16. What is the key advantage of short circuiting transfer?
To prevent leakage - Carbon Dioxide (CO2)
Minimum distortion due to low heat input
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
1/4 inch to 1/2 inch

17. What is the main purpose of 'slope'?
Voltage is the force that overcomes resistance to allow amperage flow
DCEP (Direct Current Electrode Positive) Reverse Polarity
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

18. Give a description of 'pinch effect'
The time rate of response for the current rise and fall
These terms are quite restrictive and often technically incorrect
Constant voltage (CV)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

19. Why is a fiber washer required and what cylinder gas requires it?
Constant current (CC)
Minutes of elapsed time continually run (out of 10 minutes)
Motor driven generators - Transformer rectifiers - and Inverter designs
To prevent leakage - Carbon Dioxide (CO2)

20. What does a flowmeter do and what does it measure?
12 to 22 arc volts
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
Controls the rate of flow of a shielding gas to the gun nozzle

21. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
Pressure - The rate of flow of a shielding gas
To limit the short circuiting current so that spatter is reduced
5.8 to 12.5 L/min

22. What current and polarity is generally used with GMAW?
SMAW - GTAW
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
When the filler wire is in direct contract with the base metal
DCEP (Direct Current Electrode Positive) Reverse Polarity

23. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Constant- speed wire feeders and Voltage- sennsing wire feeders
5.8 to 12.5 L/min
...
Insufficient current to melt the wire off cleanly

24. What controls amperage when using GMAW?
To limit the short circuiting current so that spatter is reduced
Cause flaking - which can clog the liner and contact tube
Wire feed speed
Controls the rate of flow of a shielding gas to the gun nozzle

25. In the GMAW process what does amperage control?
These terms are quite restrictive and often technically incorrect
Penetration and burn - off rate of the electrode
The resistace to electrical current flow increases with it. Causing the electrode to heat
Spatter problems and poor weld appearance

26. In the GMAW process what does voltage control?
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Gas metal arc welding
DCEP (Direct Current Electrode Positive) Reverse Polarity
Puddle fluidity

27. What is the maximum distance that hard wire can be successfully pushed?
15 feet (4.5 meters)
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Aluminum wire
To limit the short circuiting current so that spatter is reduced

28. Regulators control_____________ flowmeters SHOW____________.
Wire feed speed
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Pressure - The rate of flow of a shielding gas
Minimum distortion due to low heat input

29. What type of power source is used with a constant speed wire feeder?
Generally not as accurate
Constant voltage (CV)
If you dont know this check your phone
Gives arc voltage values to the control system of the feeder

30. How many times per second does short circuiting take place?
To limit the short circuiting current so that spatter is reduced
Wire feed speed
20 to 200 times per second
5.8 to 12.5 L/min

31. What does the wire feeder control?
Pressure - The rate of flow of a shielding gas
...
Speed of the feed motor and - starting / stopping electrode feed
To prevent drawing of liquid CO2 (Carbon Dioxide)

32. What is another term for electrode holders for GMAW?
Voltage is the force that overcomes resistance to allow amperage flow
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
Guns

33. What is the disadvantage of the gauge preset type of regulator/flowmeter?
The Arc voltage
Generally not as accurate
The time rate of response for the current rise and fall
The negative side of a welding unit

34. What is the recommended electrode stick- out for .035 solid wire?
The negative side of a welding unit
1/4 inch to 1/2 inch
5.8 to 12.5 L/min
If you dont know this check your phone

35. What is a solenoid valve and what actuates it?
85%
To prevent leakage - Carbon Dioxide (CO2)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Cause flaking - which can clog the liner and contact tube

36. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
Controls the rate of flow of a shielding gas to the gun nozzle
Flux cored wires
Dry ice can form within the flow control openings and cause blockage of shielding gas

37. Why is globular transfer generally avoided with GMAW?
These terms are quite restrictive and often technically incorrect
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 feed speed - Voltage control
Spatter problems and poor weld appearance

38. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Minimum distortion due to low heat input
3
Gas metal arc welding

39. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
SMAW - GTAW
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
Flux cored wires

40. List the basic equipment requirements for the GMAW process
To prevent leakage - Carbon Dioxide (CO2)
Gives arc voltage values to the control system of the feeder
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
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41. What is a typical flow rate of CO2 for short circuit transfer?
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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
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

42. What type of power source is commonly used with a voltage sensing wire feeder?
Wire feed speed - Voltage control
The time rate of response for the current rise and fall
Constant current (CC)
5.8 to 12.5 L/min

43. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Guns
Cause flaking - which can clog the liner and contact tube
Pressure vessels and the piping industry
DCEP (Direct Current Electrode Positive) Reverse Polarity

44. What power sources are used with the GMAW Process?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Motor driven generators - Transformer rectifiers - and Inverter designs
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

45. What effect does increasing and decreasing the inductance have on 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
The resistace to electrical current flow increases with it. Causing the electrode to heat
...
Reducing the gas source pressure to a constant working pressure

46. Draw a typical volt amp curve for a machine that is designed for GMAW
(DCEP) Direct Current Electrode Positive or Reverse polarity
If you dont know this check your phone
Shielding the molten weld metal from atmospheric contamination
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

47. What 2 controls are found on a GMAW set- up?
Wire feed speed
Wire feed speed - Voltage control
V groove or U groove
Constant voltage (CV)

48. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Duty cycle
National Electrical Manufactures Association

49. What is the effect of too much slope?
Cause flaking - which can clog the liner and contact tube
12 to 22 arc volts
Pressure vessels and the piping industry
Insufficient current to melt the wire off cleanly

50. What controls the wire speed on a voltage sensing wire feeder?
Dry ice can form within the flow control openings and cause blockage of shielding gas
(DCEP) Direct Current Electrode Positive or Reverse polarity
The Arc voltage
Duty cycle