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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 purpose of a regulator and what does it indicate on its gauges?
Reducing the gas source pressure to a constant working pressure
Voltage is the force that overcomes resistance to allow amperage flow
Constant- speed wire feeders and Voltage- sennsing wire feeders
Aluminum wire

2. What is the purpose of the shielding gas used in GMAW?
Puddle fluidity
Minutes of elapsed time continually run (out of 10 minutes)
Shielding the molten weld metal from atmospheric contamination
Insufficient current to melt the wire off cleanly

3. What type of power source is commonly used with a voltage sensing wire feeder?
By there current carrying capacity
...
V groove or U groove
Constant current (CC)

4. With straight polarity where is 2/3 of the arc energy?
Duty cycle
3
The negative side of a welding unit
Aluminum wire

5. What does the wire feeder control?
Minimum distortion due to low heat input
Speed of the feed motor and - starting / stopping electrode feed
Cause flaking - which can clog the liner and contact tube
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

6. What does a flowmeter do and what does it measure?
To limit the short circuiting current so that spatter is reduced
To prevent drawing of liquid CO2 (Carbon Dioxide)
15 feet (4.5 meters)
Controls the rate of flow of a shielding gas to the gun nozzle

7. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Higher 26 to 35 arc volts
Cause flaking - which can clog the liner and contact tube
V groove or U groove

8. What is a solenoid valve and what actuates it?
Welding process that joins metals by heating them with an electric arc
Controls the rate of flow of a shielding gas to the gun nozzle
Higher 26 to 35 arc volts
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

9. Regulators control_____________ flowmeters SHOW____________.
Reducing the gas source pressure to a constant working pressure
Welding process that joins metals by heating them with an electric arc
Constant voltage (CV)
Pressure - The rate of flow of a shielding gas

10. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
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The negative side of a welding unit
Cause flaking - which can clog the liner and contact tube

11. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
To limit the short circuiting current so that spatter is reduced
Wire feed speed

12. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
3
The time rate of response for the current rise and fall
National Electrical Manufactures Association

13. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Voltage is the force that overcomes resistance to allow amperage flow
Duty cycle
3
Controls the rate of flow of a shielding gas to the gun nozzle

14. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
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Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Flux cored wires

15. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
Motor driven generators - Transformer rectifiers - and Inverter designs
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
The time rate of response for the current rise and fall

16. Why must CO2 cylinders be used in the vertical position?
Wire feed speed
15 feet (4.5 meters)
To prevent drawing of liquid CO2 (Carbon Dioxide)
SMAW - GTAW

17. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
3
Flux cored wires
The time rate of response for the current rise and fall

18. What is the required arc voltage used for short circuit transfer?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
12 to 22 arc volts
The negative side of a welding unit
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

19. What is a typical flow rate of CO2 for short circuit transfer?
Speed of the feed motor and - starting / stopping electrode feed
5.8 to 12.5 L/min
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

20. Give a description of 'pinch effect'
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
AWS and CSA
Gas metal arc welding
The resistace to electrical current flow increases with it. Causing the electrode to heat

21. What effect does increasing and decreasing the inductance have on the weld?
Cause flaking - which can clog the liner and contact tube
Wire feed speed
Motor driven generators - Transformer rectifiers - and Inverter designs
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

22. What happens when the electrode extension is increased?
85%
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
Welding process that joins metals by heating them with an electric arc

23. 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
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)
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24. In the GMAW process what does voltage control?
Speed of the feed motor and - starting / stopping electrode feed
Insufficient current to melt the wire off cleanly
Minimum distortion due to low heat input
Puddle fluidity

25. What does inductance control?
The time rate of response for the current rise and fall
Reducing the gas source pressure to a constant working pressure
Flux cored wires
SMAW - GTAW

26. Draw a typical volt amp curve for a machine that is designed for GMAW
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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Constant- speed wire feeders and Voltage- sennsing wire feeders
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

27. What current and polarity is generally used with GMAW?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
To limit the short circuiting current so that spatter is reduced
...
DCEP (Direct Current Electrode Positive) Reverse Polarity

28. What 2 controls are found on a GMAW set- up?
Wire feed speed - Voltage control
1/4 inch to 1/2 inch
Guns
Flux cored wires

29. What controls the wire speed on a voltage sensing wire feeder?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Shielding the molten weld metal from atmospheric contamination
Wire feed speed - Voltage control
The Arc voltage

30. What is the key advantage of short circuiting transfer?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Reducing the gas source pressure to a constant working pressure
Minimum distortion due to low heat input
Cause flaking - which can clog the liner and contact tube

31. What is an advantage of pulsed arc transfer with GMAW?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Minutes of elapsed time continually run (out of 10 minutes)
12 to 22 arc volts

32. List the factors that determine the mode of metal transfer
To limit the short circuiting current so that spatter is reduced
AWS and CSA
The Arc voltage
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

33. Why is a fiber washer required and what cylinder gas requires it?
Minimum distortion due to low heat input
Gas metal arc welding
Minutes of elapsed time continually run (out of 10 minutes)
To prevent leakage - Carbon Dioxide (CO2)

34. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
20 to 200 times per second

35. What is the maximum distance that hard wire can be successfully pushed?
The time rate of response for the current rise and fall
15 feet (4.5 meters)
Constant current (CC)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

36. What wire are knurled drive rolls most commonly used on?
Flux cored wires
Minutes of elapsed time continually run (out of 10 minutes)
To prevent drawing of liquid CO2 (Carbon Dioxide)
Motor driven generators - Transformer rectifiers - and Inverter designs

37. List 3 wire drive systems and give a short description of each
Gives arc voltage values to the control system of the feeder
3
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

38. What does the term GMAW identify?
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
Guns
Gas metal arc welding

39. What output on the welding machine is used to rate the duty cycle?
Constant voltage (CV)
Speed of the feed motor and - starting / stopping electrode feed
Minutes of elapsed time continually run (out of 10 minutes)
When the filler wire is in direct contract with the base metal

40. When is the metal transferred with short circuit transfer?
Gas metal arc welding
1/4 inch to 1/2 inch
The time rate of response for the current rise and fall
When the filler wire is in direct contract with the base metal

41. Why is globular transfer generally avoided with GMAW?
85%
Pressure vessels and the piping industry
Spatter problems and poor weld appearance
Wire feed speed

42. List the three methods of metal transfer with GMAW
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
To prevent drawing of liquid CO2 (Carbon Dioxide)
Short- circuiting transfer - Globular transfer - Spray transfer
V groove or U groove

43. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
The time rate of response for the current rise and fall
Wire feed speed
85%
AWS and CSA

44. What is another term for electrode holders for GMAW?
Aluminum wire
Guns
Welding process that joins metals by heating them with an electric arc
Voltage is the force that overcomes resistance to allow amperage flow

45. Why is a line heater required when using GMAW?
Flux cored wires
85%
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
Dry ice can form within the flow control openings and cause blockage of shielding gas

46. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
SMAW - GTAW
...
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Minutes of elapsed time continually run (out of 10 minutes)

47. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Pressure - The rate of flow of a shielding gas
1/4 inch to 1/2 inch
AWS and CSA

48. What is the preferred drive roll design for solid wires?
Dry ice can form within the flow control openings and cause blockage of shielding gas
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
Controls the rate of flow of a shielding gas to the gun nozzle
V groove or U groove

49. Why is the term GMAW preferred over MIG or MAG?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Aluminum wire
These terms are quite restrictive and often technically incorrect
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

50. List several industries that would use GMAW
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 vessels and the piping industry
Welding process that joins metals by heating them with an electric arc
20 to 200 times per second