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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 a line heater required when using GMAW?
1/4 inch to 1/2 inch
These terms are quite restrictive and often technically incorrect
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

2. What 2 controls are found on a GMAW set- up?
Guns
12 to 22 arc volts
Wire feed speed - Voltage control
Wire feeds smoothly (yet will slip should a problem occur in the gun)

3. 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
15 feet (4.5 meters)
Wire feed speed
V groove or U groove

4. List the factors that determine the mode of metal transfer
The negative side of a welding unit
3
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Controls the rate of flow of a shielding gas to the gun nozzle

5. What wire are knurled drive rolls most commonly used on?
Pressure - The rate of flow of a shielding gas
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Flux cored wires
SMAW - GTAW

6. What does the wire feeder control?
Guns
Pressure vessels and the piping industry
Cause flaking - which can clog the liner and contact tube
Speed of the feed motor and - starting / stopping electrode feed

7. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
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
Gives arc voltage values to the control system of the feeder
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
3

8. Draw a typical volt amp curve for a machine that is designed for GMAW
Pressure - The rate of flow of a shielding gas
The time rate of response for the current rise and fall
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
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9. What type of power source is commonly used with a voltage sensing wire feeder?
Constant voltage (CV)
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Constant current (CC)
The resistace to electrical current flow increases with it. Causing the electrode to heat

10. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Insufficient current to melt the wire off cleanly
...

11. What is the recommended electrode stick- out for .035 solid wire?
(DCEP) Direct Current Electrode Positive or Reverse polarity
1/4 inch to 1/2 inch
By there current carrying capacity
...

12. What is the key advantage of short circuiting transfer?
Pressure vessels and the piping industry
Guns
The time rate of response for the current rise and fall
Minimum distortion due to low heat input

13. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Spatter problems and poor weld appearance
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Pressure vessels and the piping industry
Shielding the molten weld metal from atmospheric contamination

14. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Gives arc voltage values to the control system of the feeder
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Generally not as accurate
Voltage is the force that overcomes resistance to allow amperage flow

15. What is the maximum distance that hard wire can be successfully pushed?
The negative side of a welding unit
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Penetration and burn - off rate of the electrode
15 feet (4.5 meters)

16. What is the preferred drive roll design for solid wires?
Higher 26 to 35 arc volts
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V groove or U groove
SMAW - GTAW

17. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
Constant voltage (CV)
To limit the short circuiting current so that spatter is reduced
Pressure - The rate of flow of a shielding gas

18. Give a brief description of the GMAW process
Constant voltage (CV)
1/4 inch to 1/2 inch
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Welding process that joins metals by heating them with an electric arc

19. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
AWS and CSA
20 to 200 times per second
15 feet (4.5 meters)

20. List 3 forms compressed gases may be supplied for welding
Puddle fluidity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Constant- speed wire feeders and Voltage- sennsing wire feeders
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

21. A 10 minute cycle of welding time vs cooling time a given machine can handle.
20 to 200 times per second
Shielding the molten weld metal from atmospheric contamination
Duty cycle
Constant- speed wire feeders and Voltage- sennsing wire feeders

22. What is the purpose of the shielding gas used in GMAW?
Generally not as accurate
The negative side of a welding unit
Shielding the molten weld metal from atmospheric contamination
Guns

23. What processes are constant current (CC) power sources designed to be used with?
The time rate of response for the current rise and fall
Gives arc voltage values to the control system of the feeder
SMAW - GTAW
Generally not as accurate

24. Why is the term GMAW preferred over MIG or MAG?
To prevent drawing of liquid CO2 (Carbon Dioxide)
The negative side of a welding unit
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
These terms are quite restrictive and often technically incorrect

25. List the basic equipment requirements for the GMAW process
Aluminum wire
Minutes of elapsed time continually run (out of 10 minutes)
Motor driven generators - Transformer rectifiers - and Inverter designs
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

26. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
(DCEP) Direct Current Electrode Positive or Reverse polarity
The Arc voltage
To limit the short circuiting current so that spatter is reduced

27. What does voltage do in an electrical circuit?
5.8 to 12.5 L/min
Constant voltage (CV)
Voltage is the force that overcomes resistance to allow amperage flow
Dry ice can form within the flow control openings and cause blockage of shielding gas

28. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
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
Minimum distortion due to low heat input
Cause flaking - which can clog the liner and contact tube

29. What is the required arc voltage used for short circuit transfer?
12 to 22 arc volts
When the filler wire is in direct contract with the base metal
Gives arc voltage values to the control system of the feeder
Generally not as accurate

30. What effect does increasing and decreasing the inductance have on the weld?
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 leakage - Carbon Dioxide (CO2)
AWS and CSA

31. In the GMAW process what does voltage control?
The negative side of a welding unit
AWS and CSA
Puddle fluidity
Wire feed speed

32. 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
Gas metal arc welding
Spatter problems and poor weld appearance
Gives arc voltage values to the control system of the feeder

33. 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
The Arc voltage
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

34. What is an advantage of pulsed arc transfer with GMAW?
Flux cored wires
To prevent drawing of liquid CO2 (Carbon Dioxide)
Constant current (CC)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

35. List several industries that would use GMAW
1/4 inch to 1/2 inch
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 Current - Filler wire diameter - arc length - type of shielding - position of the weld
Pressure vessels and the piping industry

36. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
National Electrical Manufactures Association
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Flux cored wires

37. What 2 organizations designate specifications for GMAW wires?
Wire feed speed
3
AWS and CSA
The Arc voltage

38. How are GMAW guns rated?
Gas metal arc welding
By there current carrying capacity
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
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

39. What would be an indication that the drive roll pressure is adjusted correctly?
Guns
Aluminum wire
Pressure - The rate of flow of a shielding gas
Wire feeds smoothly (yet will slip should a problem occur in the gun)

40. What does inductance control?
Constant current (CC)
To limit the short circuiting current so that spatter is reduced
By there current carrying capacity
The time rate of response for the current rise and fall

41. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Flux cored wires
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
20 to 200 times per second

42. 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
National Electrical Manufactures Association
3
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43. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
Spatter problems and poor weld appearance
When the filler wire is in direct contract with the base metal
By there current carrying capacity

44. What are the 2 types of wire feeders available?
Wire feed speed
Constant voltage (CV)
Constant- speed wire feeders and Voltage- sennsing wire feeders
Higher 26 to 35 arc volts

45. When is the metal transferred with short circuit transfer?
When the filler wire is in direct contract with the base metal
Dry ice can form within the flow control openings and cause blockage of shielding gas
Insufficient current to melt the wire off cleanly
Wire feed speed - Voltage control

46. What current and polarity is generally used with GMAW?
The Arc voltage
Constant current (CC)
Wire feed speed - Voltage control
DCEP (Direct Current Electrode Positive) Reverse Polarity

47. 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
Constant current (CC)
Pressure vessels and the piping industry
Minimum distortion due to low heat input

48. Give a description of 'pinch effect'
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
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
Wire feeds smoothly (yet will slip should a problem occur in the gun)

49. What output on the welding machine is used to rate the duty cycle?
85%
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Duty cycle
Minutes of elapsed time continually run (out of 10 minutes)

50. What does the term GMAW identify?
Cause flaking - which can clog the liner and contact tube
If you dont know this check your phone
Constant voltage (CV)
Gas metal arc welding