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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 controls the wire speed on a voltage sensing wire feeder?
Spatter problems and poor weld appearance
The Arc voltage
Shielding the molten weld metal from atmospheric contamination
(DCEP) Direct Current Electrode Positive or Reverse polarity

2. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
3
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
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3. What is a solenoid valve and what actuates it?
1/4 inch to 1/2 inch
3
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

4. What does the abbreviation NEMA stand for?
Constant voltage (CV)
National Electrical Manufactures Association
Dry ice can form within the flow control openings and cause blockage of shielding gas
Gives arc voltage values to the control system of the feeder

5. List the basic equipment requirements for the GMAW process
The Arc voltage
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
The time rate of response for the current rise and fall
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

6. Why is a line heater required when using GMAW?
85%
The time rate of response for the current rise and fall
Controls the rate of flow of a shielding gas to the gun nozzle
Dry ice can form within the flow control openings and cause blockage of shielding gas

7. 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
Cause flaking - which can clog the liner and contact tube
By there current carrying capacity
Minimum distortion due to low heat input

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

9. What wire are knurled drive rolls most commonly used on?
Duty cycle
Flux cored wires
Aluminum wire
Shielding the molten weld metal from atmospheric contamination

10. What is the effect of too much slope?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Constant current (CC)
Insufficient current to melt the wire off cleanly
Cause flaking - which can clog the liner and contact tube

11. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Constant voltage (CV)
Motor driven generators - Transformer rectifiers - and Inverter designs
Duty cycle
Insufficient current to melt the wire off cleanly

12. Give a brief description of the GMAW process
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
Wire feed speed - Voltage control

13. 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%
DCEP (Direct Current Electrode Positive) Reverse Polarity
Generally not as accurate

14. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
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
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The time rate of response for the current rise and fall

15. A pull type drive system is usually used on what type of material?
To limit the short circuiting current so that spatter is reduced
Aluminum wire
85%
(DCEP) Direct Current Electrode Positive or Reverse polarity

16. What is a typical flow rate of CO2 for short circuit transfer?
3
Wire feed speed
5.8 to 12.5 L/min
Reducing the gas source pressure to a constant working pressure

17. List the factors that determine the mode of metal transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
85%
12 to 22 arc volts
Pressure vessels and the piping industry

18. When is the metal transferred with short circuit transfer?
20 to 200 times per second
When the filler wire is in direct contract with the base metal
Puddle fluidity
Spatter problems and poor weld appearance

19. What does the term GMAW identify?
Shielding the molten weld metal from atmospheric contamination
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Gas metal arc welding
20 to 200 times per second

20. What happens when the electrode extension is increased?
Minimum distortion due to low heat input
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The resistace to electrical current flow increases with it. Causing the electrode to heat
SMAW - GTAW

21. List 3 wire drive systems and give a short description of each
Cause flaking - which can clog the liner and contact tube
Spatter problems and poor weld appearance
Gas metal arc welding
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

22. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Aluminum wire
Cause flaking - which can clog the liner and contact tube
Welding process that joins metals by heating them with an electric arc

23. What is the preferred drive roll design for solid wires?
1/4 inch to 1/2 inch
V groove or U groove
3
Wire feed speed - Voltage control

24. What is an advantage of pulsed arc transfer with GMAW?
Constant voltage (CV)
Pressure vessels and the piping industry
Wire feed speed
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

25. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
To prevent leakage - Carbon Dioxide (CO2)
15 feet (4.5 meters)
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

26. What would be an indication that the drive roll pressure is adjusted correctly?
Cause flaking - which can clog the liner and contact tube
Wire feeds smoothly (yet will slip should a problem occur in the gun)
1/4 inch to 1/2 inch
By there current carrying capacity

27. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
By there current carrying capacity
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When the filler wire is in direct contract with the base metal

28. What does voltage do in an electrical circuit?
Aluminum wire
Duty cycle
Voltage is the force that overcomes resistance to allow amperage flow
5.8 to 12.5 L/min

29. What does the wire feeder control?
1/4 inch to 1/2 inch
Reducing the gas source pressure to a constant working pressure
Guns
Speed of the feed motor and - starting / stopping electrode feed

30. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Wire feed speed - Voltage control
Cause flaking - which can clog the liner and contact tube
3

31. What is the main purpose of 'slope'?
Wire feed speed - Voltage control
To limit the short circuiting current so that spatter is reduced
SMAW - GTAW
V groove or U groove

32. What 2 organizations designate specifications for GMAW wires?
3
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AWS and CSA
Dry ice can form within the flow control openings and cause blockage of shielding gas

33. What is the purpose of a regulator and what does it indicate on its gauges?
Reducing the gas source pressure to a constant working pressure
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Higher 26 to 35 arc volts
Constant current (CC)

34. Give a description of 'pinch effect'
Constant current (CC)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Cause flaking - which can clog the liner and contact tube
Motor driven generators - Transformer rectifiers - and Inverter designs

35. What does inductance control?
1/4 inch to 1/2 inch
Gives arc voltage values to the control system of the feeder
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. What current and polarity is generally used with GMAW?
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DCEP (Direct Current Electrode Positive) Reverse Polarity
Puddle fluidity

37. List several industries that would use GMAW
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Pressure vessels and the piping industry
Cause flaking - which can clog the liner and contact tube
85%

38. What type of power source is used with a constant speed wire feeder?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Constant voltage (CV)
Duty cycle
Pressure vessels and the piping industry

39. What 2 controls are found on a GMAW set- up?
1/4 inch to 1/2 inch
Wire feed speed - Voltage control
Wire feeds smoothly (yet will slip should a problem occur in the gun)
When the filler wire is in direct contract with the base metal

40. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Generally not as accurate
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Cause flaking - which can clog the liner and contact tube
Higher 26 to 35 arc volts

41. Why is the term GMAW preferred over MIG or MAG?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Guns
Wire feeds smoothly (yet will slip should a problem occur in the gun)
These terms are quite restrictive and often technically incorrect

42. With straight polarity where is 2/3 of the arc energy?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Welding process that joins metals by heating them with an electric arc
The negative side of a welding unit
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

43. What is the maximum distance that hard wire can be successfully pushed?
15 feet (4.5 meters)
National Electrical Manufactures Association
Motor driven generators - Transformer rectifiers - and Inverter designs
1/4 inch to 1/2 inch

44. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
...
3
Constant voltage (CV)
Gives arc voltage values to the control system of the feeder

45. In the GMAW process what does voltage control?
Gives arc voltage values to the control system of the feeder
...
Puddle fluidity
Guns

46. Why must CO2 cylinders be used in the vertical position?
Reducing the gas source pressure to a constant working pressure
To prevent drawing of liquid CO2 (Carbon Dioxide)
Aluminum wire
20 to 200 times per second

47. What output on the welding machine is used to rate the duty cycle?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Minutes of elapsed time continually run (out of 10 minutes)
1/4 inch to 1/2 inch
Controls the rate of flow of a shielding gas to the gun nozzle

48. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
Dry ice can form within the flow control openings and cause blockage of shielding gas
To prevent drawing of liquid CO2 (Carbon Dioxide)
If you dont know this check your phone

49. What power sources are used with the GMAW Process?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Short- circuiting transfer - Globular transfer - Spray transfer
Constant- speed wire feeders and Voltage- sennsing wire feeders
Motor driven generators - Transformer rectifiers - and Inverter designs

50. What type of power source is commonly used with a voltage sensing wire feeder?
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
Puddle fluidity
Constant current (CC)
Short- circuiting transfer - Globular transfer - Spray transfer