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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. Why is the term GMAW preferred over MIG or MAG?
The Arc voltage
These terms are quite restrictive and often technically incorrect
Wire feed speed
Aluminum wire

2. What 2 organizations designate specifications for GMAW wires?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Puddle fluidity
Speed of the feed motor and - starting / stopping electrode feed
AWS and CSA

3. In the GMAW process what does voltage control?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Gas metal arc welding
1/4 inch to 1/2 inch
Puddle fluidity

4. Why must CO2 cylinders be used in the vertical position?
12 to 22 arc volts
Insufficient current to melt the wire off cleanly
To prevent drawing of liquid CO2 (Carbon Dioxide)
Constant voltage (CV)

5. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
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)

6. What is the main purpose of 'slope'?
To prevent drawing of liquid CO2 (Carbon Dioxide)
To limit the short circuiting current so that spatter is reduced
National Electrical Manufactures Association
(DCEP) Direct Current Electrode Positive or Reverse polarity

7. Give a brief description of the GMAW process
Wire feed speed
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
The Arc voltage
Welding process that joins metals by heating them with an electric arc

8. A 10 minute cycle of welding time vs cooling time a given machine can handle.
15 feet (4.5 meters)
85%
Duty cycle
1/4 inch to 1/2 inch

9. What would be an indication that the drive roll pressure is adjusted correctly?
Spatter problems and poor weld appearance
Wire feeds smoothly (yet will slip should a problem occur in the gun)
National Electrical Manufactures Association
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

10. Why is a line heater required when using GMAW?
5.8 to 12.5 L/min
Minimum distortion due to low heat input
Higher 26 to 35 arc volts
Dry ice can form within the flow control openings and cause blockage of shielding gas

11. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
...
Dry ice can form within the flow control openings and cause blockage of shielding gas
By there current carrying capacity
If you dont know this check your phone

12. List the factors that determine the mode of metal transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
AWS and CSA
To prevent drawing of liquid CO2 (Carbon Dioxide)
Gives arc voltage values to the control system of the feeder

13. What does a flowmeter do and what does it measure?
Higher 26 to 35 arc volts
Controls the rate of flow of a shielding gas to the gun nozzle
Aluminum wire
Minimum distortion due to low heat input

14. What current and polarity is generally used with GMAW?
Penetration and burn - off rate of the electrode
DCEP (Direct Current Electrode Positive) Reverse Polarity
Flux cored wires
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. What is the preferred drive roll design for solid wires?
Gives arc voltage values to the control system of the feeder
Controls the rate of flow of a shielding gas to the gun nozzle
V groove or U groove
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

16. What is another term for electrode holders for GMAW?
Minutes of elapsed time continually run (out of 10 minutes)
Guns
Generally not as accurate
Wire feeds smoothly (yet will slip should a problem occur in the gun)

17. How many times per second does short circuiting take place?
The negative side of a welding unit
To prevent drawing of liquid CO2 (Carbon Dioxide)
Pressure - The rate of flow of a shielding gas
20 to 200 times per second

18. Give a description of 'pinch effect'
Generally not as accurate
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)
...

19. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
When the filler wire is in direct contract with the base metal
Gas metal arc welding
Motor driven generators - Transformer rectifiers - and Inverter designs

20. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Guns
...
If you dont know this check your phone
To prevent drawing of liquid CO2 (Carbon Dioxide)

21. What is a typical flow rate of CO2 for short circuit transfer?
Gives arc voltage values to the control system of the feeder
Wire feed speed - Voltage control
SMAW - GTAW
5.8 to 12.5 L/min

22. What does the wire feeder control?
Welding process that joins metals by heating them with an electric arc
These terms are quite restrictive and often technically incorrect
Speed of the feed motor and - starting / stopping electrode feed
Pressure vessels and the piping industry

23. When is the metal transferred with short circuit transfer?
To limit the short circuiting current so that spatter is reduced
When the filler wire is in direct contract with the base metal
Minimum distortion due to low heat input
Constant current (CC)

24. What processes are constant current (CC) power sources designed to be used with?
Aluminum wire
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Insufficient current to melt the wire off cleanly
SMAW - GTAW

25. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Duty cycle
Insufficient current to melt the wire off cleanly
Higher 26 to 35 arc volts
Guns

26. List several industries that would use GMAW
Controls the rate of flow of a shielding gas to the gun nozzle
Pressure vessels and the piping industry
Pressure - The rate of flow of a shielding gas
12 to 22 arc volts

27. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
1/4 inch to 1/2 inch
Speed of the feed motor and - starting / stopping electrode feed

28. What is the purpose of a regulator and what does it indicate on its gauges?
Cause flaking - which can clog the liner and contact tube
15 feet (4.5 meters)
To prevent leakage - Carbon Dioxide (CO2)
Reducing the gas source pressure to a constant working pressure

29. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Motor driven generators - Transformer rectifiers - and Inverter designs
3
The negative side of a welding unit
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

30. What wire are knurled drive rolls most commonly used on?
Pressure vessels and the piping industry
By there current carrying capacity
The resistace to electrical current flow increases with it. Causing the electrode to heat
Flux cored wires

31. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
When the filler wire is in direct contract with the base metal
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
The Arc voltage
(DCEP) Direct Current Electrode Positive or Reverse polarity

32. What does voltage do in an electrical circuit?
Duty cycle
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
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Voltage is the force that overcomes resistance to allow amperage flow

33. What is the purpose of the shielding gas used in GMAW?
Pressure - The rate of flow of a shielding gas
Shielding the molten weld metal from atmospheric contamination
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
1/4 inch to 1/2 inch

34. List the three methods of metal transfer with GMAW
If you dont know this check your phone
Voltage is the force that overcomes resistance to allow amperage flow
Pressure vessels and the piping industry
Short- circuiting transfer - Globular transfer - Spray transfer

35. What does inductance control?
The negative side of a welding unit
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
The time rate of response for the current rise and fall
...

36. Why is globular transfer generally avoided with GMAW?
Higher 26 to 35 arc volts
Spatter problems and poor weld appearance
When the filler wire is in direct contract with the base metal
The Arc voltage

37. What is a solenoid valve and what actuates it?
DCEP (Direct Current Electrode Positive) Reverse Polarity
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
If you dont know this check your phone

38. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
15 feet (4.5 meters)
Constant- speed wire feeders and Voltage- sennsing wire feeders
(DCEP) Direct Current Electrode Positive or Reverse polarity
Cause flaking - which can clog the liner and contact tube

39. What is the required arc voltage used for short circuit transfer?
20 to 200 times per second
12 to 22 arc volts
3
Controls the rate of flow of a shielding gas to the gun nozzle

40. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
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
Generally not as accurate

41. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Controls the rate of flow of a shielding gas to the gun nozzle
Higher 26 to 35 arc volts
Gives arc voltage values to the control system of the feeder

42. List 3 forms compressed gases may be supplied for welding
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Aluminum wire
Pressure - The rate of flow of a shielding gas

43. What 2 controls are found on a GMAW set- up?
Constant current (CC)
Wire feed speed - Voltage control
Generally not as accurate
Pressure vessels and the piping industry

44. A pull type drive system is usually used on what type of material?
Higher 26 to 35 arc volts
Spatter problems and poor weld appearance
Aluminum wire
To prevent drawing of liquid CO2 (Carbon Dioxide)

45. What does the abbreviation NEMA stand for?
If you dont know this check your phone
1/4 inch to 1/2 inch
National Electrical Manufactures Association
Aluminum wire

46. What happens when the electrode extension is increased?
20 to 200 times per second
The resistace to electrical current flow increases with it. Causing the electrode to heat
If you dont know this check your phone
Constant current (CC)

47. In the GMAW process what does amperage control?
1/4 inch to 1/2 inch
Speed of the feed motor and - starting / stopping electrode feed
Minimum distortion due to low heat input
Penetration and burn - off rate of the electrode

48. How are GMAW guns rated?
Constant current (CC)
Reducing the gas source pressure to a constant working pressure
By there current carrying capacity
Guns

49. What type of power source is commonly used with a voltage sensing wire feeder?
Wire feed speed - Voltage control
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
...
Constant current (CC)

50. What controls amperage when using GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
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