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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 does the wire feeder control?
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
V groove or U groove
Speed of the feed motor and - starting / stopping electrode feed
12 to 22 arc volts

2. List 3 forms compressed gases may be supplied for welding
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Controls the rate of flow of a shielding gas to the gun nozzle
Welding process that joins metals by heating them with an electric arc

3. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Higher 26 to 35 arc volts
Wire feed speed
Cause flaking - which can clog the liner and contact tube

4. What output on the welding machine is used to rate the duty cycle?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Minutes of elapsed time continually run (out of 10 minutes)
Gives arc voltage values to the control system of the feeder
AWS and CSA

5. What is a typical flow rate of CO2 for short circuit transfer?
Gives arc voltage values to the control system of the feeder
15 feet (4.5 meters)
5.8 to 12.5 L/min
Welding process that joins metals by heating them with an electric arc

6. When is the metal transferred with short circuit transfer?
Motor driven generators - Transformer rectifiers - and Inverter designs
(DCEP) Direct Current Electrode Positive or Reverse polarity
When the filler wire is in direct contract with the base metal
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

7. What does the term GMAW identify?
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Gas metal arc welding
85%
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

8. What current and polarity is generally used with GMAW?
The time rate of response for the current rise and fall
Constant voltage (CV)
DCEP (Direct Current Electrode Positive) Reverse Polarity
Insufficient current to melt the wire off cleanly

9. What is the key advantage of short circuiting transfer?
Flux cored wires
The Arc voltage
Penetration and burn - off rate of the electrode
Minimum distortion due to low heat input

10. List several industries that would use GMAW
5.8 to 12.5 L/min
Insufficient current to melt the wire off cleanly
Pressure vessels and the piping industry
Penetration and burn - off rate of the electrode

11. Why is globular transfer generally avoided with GMAW?
Minimum distortion due to low heat input
Higher 26 to 35 arc volts
By there current carrying capacity
Spatter problems and poor weld appearance

12. Why is a line heater required when using GMAW?
Reducing the gas source pressure to a constant working pressure
Dry ice can form within the flow control openings and cause blockage of shielding gas
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Puddle fluidity

13. What is another term for electrode holders for GMAW?
Pressure - The rate of flow of a shielding gas
The negative side of a welding unit
Guns
Duty cycle

14. What 2 controls are found on a GMAW set- up?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Wire feed speed - Voltage control
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15. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
The Arc voltage
Controls the rate of flow of a shielding gas to the gun nozzle
...
Minimum distortion due to low heat input

16. What is the maximum distance that hard wire can be successfully pushed?
Wire feed speed - Voltage control
Speed of the feed motor and - starting / stopping electrode feed
Constant voltage (CV)
15 feet (4.5 meters)

17. In the GMAW process what does amperage control?
Puddle fluidity
Wire feed speed
To prevent drawing of liquid CO2 (Carbon Dioxide)
Penetration and burn - off rate of the electrode

18. In the GMAW process what does voltage control?
Puddle fluidity
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
Guns
Wire feed speed

19. What would be an indication that the drive roll pressure is adjusted correctly?
These terms are quite restrictive and often technically incorrect
AWS and CSA
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)

20. List the basic equipment requirements for the GMAW process
To limit the short circuiting current so that spatter is reduced
Gas metal arc welding
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Higher 26 to 35 arc volts

21. What happens when the electrode extension is increased?
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
...
Dry ice can form within the flow control openings and cause blockage of shielding gas

22. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
These terms are quite restrictive and often technically incorrect
Minutes of elapsed time continually run (out of 10 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

23. What controls amperage when using GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Wire feed speed
Dry ice can form within the flow control openings and cause blockage of shielding gas
Speed of the feed motor and - starting / stopping electrode feed

24. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
Voltage is the force that overcomes resistance to allow amperage flow
To limit the short circuiting current so that spatter is reduced
To prevent leakage - Carbon Dioxide (CO2)

25. Regulators control_____________ flowmeters SHOW____________.
Wire feed speed
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Welding process that joins metals by heating them with an electric arc
Pressure - The rate of flow of a shielding gas

26. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
The Arc voltage
Puddle fluidity
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Wire feed speed

27. List the factors that determine the mode of metal transfer
When the filler wire is in direct contract with the base metal
Short- circuiting transfer - Globular transfer - Spray transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Higher 26 to 35 arc volts

28. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
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Gives arc voltage values to the control system of the feeder
The resistace to electrical current flow increases with it. Causing the electrode to heat

29. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
15 feet (4.5 meters)
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(DCEP) Direct Current Electrode Positive or Reverse polarity
The negative side of a welding unit

30. List the three methods of metal transfer with GMAW
(DCEP) Direct Current Electrode Positive or Reverse polarity
Penetration and burn - off rate of the electrode
Insufficient current to melt the wire off cleanly
Short- circuiting transfer - Globular transfer - Spray transfer

31. Why must CO2 cylinders be used in the vertical position?
Welding Current - Filler wire diameter - arc length - type of shielding - position of 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
To prevent drawing of liquid CO2 (Carbon Dioxide)

32. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Short- circuiting transfer - Globular transfer - Spray transfer
85%
Guns
These terms are quite restrictive and often technically incorrect

33. List 3 wire drive systems and give a short description of each
Pressure - The rate of flow of a shielding gas
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
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
To prevent drawing of liquid CO2 (Carbon Dioxide)

34. How many times per second does short circuiting take place?
Insufficient current to melt the wire off cleanly
Minutes of elapsed time continually run (out of 10 minutes)
20 to 200 times per second
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35. What is the purpose of the shielding gas used in GMAW?
15 feet (4.5 meters)
The negative side of a welding unit
Shielding the molten weld metal from atmospheric contamination
Insufficient current to melt the wire off cleanly

36. With straight polarity where is 2/3 of the arc energy?
Wire feed speed - Voltage control
20 to 200 times per second
Reducing the gas source pressure to a constant working pressure
The negative side of a welding unit

37. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Wire feed speed
Wire feeds smoothly (yet will slip should a problem occur in the gun)
20 to 200 times per second
Cause flaking - which can clog the liner and contact tube

38. What is an advantage of pulsed arc transfer with GMAW?
1/4 inch to 1/2 inch
National Electrical Manufactures Association
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Insufficient current to melt the wire off cleanly

39. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
12 to 22 arc volts
Short- circuiting transfer - Globular transfer - Spray transfer
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

40. What type of power source is commonly used with a voltage sensing wire feeder?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Constant current (CC)
Short- circuiting transfer - Globular transfer - Spray transfer
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

41. What is a solenoid valve and what actuates it?
12 to 22 arc volts
AWS and CSA
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
The Arc voltage

42. Why is a fiber washer required and what cylinder gas requires it?
Controls the rate of flow of a shielding gas to the gun nozzle
Cause flaking - which can clog the liner and contact tube
To prevent leakage - Carbon Dioxide (CO2)
Pressure vessels and the piping industry

43. What does a flowmeter do and what does it measure?
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
Pressure vessels and the piping industry
The Arc voltage
Controls the rate of flow of a shielding gas to the gun nozzle

44. How are GMAW guns rated?
By there current carrying capacity
Flux cored wires
85%
Minutes of elapsed time continually run (out of 10 minutes)

45. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
V groove or U groove
Wire feed speed - Voltage control
If you dont know this check your phone

46. What does voltage do in an electrical circuit?
Flux cored wires
Voltage is the force that overcomes resistance to allow amperage flow
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

47. What wire are knurled drive rolls most commonly used on?
Constant voltage (CV)
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
(DCEP) Direct Current Electrode Positive or Reverse polarity

48. A pull type drive system is usually used on what type of material?
Aluminum wire
National Electrical Manufactures Association
15 feet (4.5 meters)
Puddle fluidity

49. What is the preferred drive roll design for solid wires?
V groove or U groove
To prevent drawing of liquid CO2 (Carbon Dioxide)
1/4 inch to 1/2 inch
Gives arc voltage values to the control system of the feeder

50. What is the required arc voltage used for short circuit transfer?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
12 to 22 arc volts
Constant- speed wire feeders and Voltage- sennsing wire feeders
Voltage is the force that overcomes resistance to allow amperage flow