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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 happens when the electrode extension is increased?
Shielding the molten weld metal from atmospheric contamination
Controls the rate of flow of a shielding gas to the gun nozzle
V groove or U groove
The resistace to electrical current flow increases with it. Causing the electrode to heat

2. What is the preferred drive roll design for solid wires?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
V groove or U groove
SMAW - GTAW
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

3. What controls the wire speed on a voltage sensing wire feeder?
Wire feed speed - Voltage control
Voltage is the force that overcomes resistance to allow amperage flow
The Arc voltage
Aluminum wire

4. What wire are knurled drive rolls most commonly used on?
Pressure - The rate of flow of a shielding gas
Flux cored wires
Wire feed speed - Voltage control
Minimum distortion due to low heat input

5. What is a solenoid valve and what actuates it?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Wire feed speed - Voltage control
To prevent drawing of liquid CO2 (Carbon Dioxide)
Minutes of elapsed time continually run (out of 10 minutes)

6. Draw a typical volt amp curve for a machine that is designed for GMAW
5.8 to 12.5 L/min
Constant voltage (CV)
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Controls the rate of flow of a shielding gas to the gun nozzle

7. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
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Duty cycle
Cause flaking - which can clog the liner and contact tube
These terms are quite restrictive and often technically incorrect

8. What is the purpose of the shielding gas used in GMAW?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Dry ice can form within the flow control openings and cause blockage of shielding gas
Spatter problems and poor weld appearance
Shielding the molten weld metal from atmospheric contamination

9. What 2 controls are found on a GMAW set- up?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Wire feed speed - Voltage control
The resistace to electrical current flow increases with it. Causing the electrode to heat
85%

10. What is another term for electrode holders for GMAW?
5.8 to 12.5 L/min
Guns
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Shielding the molten weld metal from atmospheric contamination

11. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Speed of the feed motor and - starting / stopping electrode feed
Generally not as accurate
Welding process that joins metals by heating them with an electric arc
3

12. List several industries that would use GMAW
National Electrical Manufactures Association
To prevent leakage - Carbon Dioxide (CO2)
(DCEP) Direct Current Electrode Positive or Reverse polarity
Pressure vessels and the piping industry

13. When is the metal transferred with short circuit transfer?
When the filler wire is in direct contract with the base metal
Penetration and burn - off rate of the electrode
These terms are quite restrictive and often technically incorrect
To limit the short circuiting current so that spatter is reduced

14. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
SMAW - GTAW
3

15. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Spatter problems and poor weld appearance
Pressure vessels and the piping industry
Minutes of elapsed time continually run (out of 10 minutes)

16. What is an advantage of pulsed arc transfer with GMAW?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Flux cored wires
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

17. Why is the term GMAW preferred over MIG or MAG?
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Wire feeds smoothly (yet will slip should a problem occur in the gun)
Welding process that joins metals by heating them with an electric arc
These terms are quite restrictive and often technically incorrect

18. Why must CO2 cylinders be used in the vertical position?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
To limit the short circuiting current so that spatter is reduced
To prevent drawing of liquid CO2 (Carbon Dioxide)
Minimum distortion due to low heat input

19. A 10 minute cycle of welding time vs cooling time a given machine can handle.
12 to 22 arc volts
Duty cycle
Cause flaking - which can clog the liner and contact tube
Pressure vessels and the piping industry

20. 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
To prevent leakage - Carbon Dioxide (CO2)
Wire feed speed - Voltage control
Pressure - The rate of flow of a shielding gas

21. What is the recommended electrode stick- out for .035 solid wire?
By there current carrying capacity
1/4 inch to 1/2 inch
Pressure vessels and the piping industry
Constant voltage (CV)

22. What effect does increasing and decreasing the inductance have on the weld?
SMAW - GTAW
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
Cause flaking - which can clog the liner and contact tube

23. What current and polarity is generally used with GMAW?
Controls the rate of flow of a shielding gas to the gun nozzle
Insufficient current to melt the wire off cleanly
DCEP (Direct Current Electrode Positive) Reverse Polarity
Penetration and burn - off rate of the electrode

24. What is the main purpose of 'slope'?
Minimum distortion due to low heat input
Controls the rate of flow of a shielding gas to the gun nozzle
To limit the short circuiting current so that spatter is reduced
Speed of the feed motor and - starting / stopping electrode feed

25. What is the key advantage of short circuiting transfer?
1/4 inch to 1/2 inch
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Pressure vessels and the piping industry
Minimum distortion due to low heat input

26. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
To prevent drawing of liquid CO2 (Carbon Dioxide)
Pressure vessels and the piping industry
Reducing the gas source pressure to a constant working pressure

27. What does inductance control?
Gas metal arc welding
To limit the short circuiting current so that spatter is reduced
Pressure vessels and the piping industry
The time rate of response for the current rise and fall

28. What output on the welding machine is used to rate the duty cycle?
Generally not as accurate
To prevent leakage - Carbon Dioxide (CO2)
Minutes of elapsed time continually run (out of 10 minutes)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

29. What controls amperage when using GMAW?
Pressure vessels and the piping industry
Motor driven generators - Transformer rectifiers - and Inverter designs
Controls the rate of flow of a shielding gas to the gun nozzle
Wire feed speed

30. What does the term GMAW identify?
The resistace to electrical current flow increases with it. Causing the electrode to heat
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Gas metal arc welding
Constant- speed wire feeders and Voltage- sennsing wire feeders

31. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Motor driven generators - Transformer rectifiers - and Inverter designs
Cause flaking - which can clog the liner and contact tube
Pressure vessels and the piping industry
Short- circuiting transfer - Globular transfer - Spray transfer

32. What processes are constant current (CC) power sources designed to be used with?
Motor driven generators - Transformer rectifiers - and Inverter designs
85%
Generally not as accurate
SMAW - GTAW

33. What 2 organizations designate specifications for GMAW wires?
The time rate of response for the current rise and fall
Penetration and burn - off rate of the electrode
Puddle fluidity
AWS and CSA

34. Give a description of 'pinch effect'
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
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
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35. What is the maximum distance that hard wire can be successfully pushed?
15 feet (4.5 meters)
Wire feed speed
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Higher 26 to 35 arc volts

36. In the GMAW process what does amperage control?
The negative side of a welding unit
(DCEP) Direct Current Electrode Positive or Reverse polarity
By there current carrying capacity
Penetration and burn - off rate of the electrode

37. What would be an indication that the drive roll pressure is adjusted correctly?
To limit the short circuiting current so that spatter is reduced
Short- circuiting transfer - Globular transfer - Spray transfer
Wire feeds smoothly (yet will slip should a problem occur in 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

38. With straight polarity where is 2/3 of the arc energy?
Gives arc voltage values to the control system of the feeder
Wire feeds smoothly (yet will slip should a problem occur in the gun)
The negative side of a welding unit
20 to 200 times per second

39. List 3 forms compressed gases may be supplied for welding
AWS and CSA
SMAW - GTAW
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
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40. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Aluminum wire
Wire feed speed - Voltage control
Controls the rate of flow of a shielding gas to the gun nozzle

41. 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
Insufficient current to melt the wire off cleanly
Flux cored wires
20 to 200 times per second

42. Why is a fiber washer required and what cylinder gas requires it?
...
By there current carrying capacity
To prevent leakage - Carbon Dioxide (CO2)
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43. A pull type drive system is usually used on what type of material?
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 limit the short circuiting current so that spatter is reduced
Aluminum wire
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

44. In the GMAW process what does voltage 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
Puddle fluidity
Controls the rate of flow of a shielding gas to the gun nozzle

45. Give a brief description of the GMAW process
These terms are quite restrictive and often technically incorrect
Speed of the feed motor and - starting / stopping electrode feed
Welding process that joins metals by heating them with an electric arc
Penetration and burn - off rate of the electrode

46. What does the wire feeder control?
20 to 200 times per second
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
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Speed of the feed motor and - starting / stopping electrode feed

47. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
AWS and CSA
85%
When the filler wire is in direct contract with the base metal
By there current carrying capacity

48. Regulators control_____________ flowmeters SHOW____________.
By there current carrying capacity
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Pressure - The rate of flow of a shielding gas
Controls the rate of flow of a shielding gas to the gun nozzle

49. What type of power source is commonly used with a voltage sensing wire feeder?
Voltage is the force that overcomes resistance to allow amperage flow
Reducing the gas source pressure to a constant working pressure
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
Constant current (CC)

50. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
AWS and CSA
Dry ice can form within the flow control openings and cause blockage of shielding gas
Wire feed speed - Voltage control
3