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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 voltage do in an electrical circuit?
Reducing the gas source pressure to a constant working pressure
V groove or U groove
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
Voltage is the force that overcomes resistance to allow amperage flow

2. What is the maximum distance that hard wire can be successfully pushed?
15 feet (4.5 meters)
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
Wire feed speed
The negative side of a welding unit

3. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
15 feet (4.5 meters)
Gives arc voltage values to the control system of the feeder
DCEP (Direct Current Electrode Positive) Reverse Polarity
Spatter problems and poor weld appearance

4. What is an advantage of pulsed arc transfer with GMAW?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
The resistace to electrical current flow increases with it. Causing the electrode to heat
...
Wire feed speed - Voltage control

5. List the basic equipment requirements for the GMAW process
The Arc voltage
Gas metal arc welding
To prevent leakage - Carbon Dioxide (CO2)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

6. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
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
V groove or U groove

7. With straight polarity where is 2/3 of the arc energy?
Aluminum wire
The negative side of a welding unit
Controls the rate of flow of a shielding gas to the gun nozzle
Wire feed speed - Voltage control

8. What type of power source is used with a constant speed wire feeder?
Puddle fluidity
Pressure vessels and the piping industry
Constant voltage (CV)
Gas metal arc welding

9. What controls the wire speed on a voltage sensing wire feeder?
AWS and CSA
Wire feed speed
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The Arc voltage

10. 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
5.8 to 12.5 L/min
Reducing the gas source pressure to a constant working pressure
Minutes of elapsed time continually run (out of 10 minutes)

11. In the GMAW process what does amperage control?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Penetration and burn - off rate of the electrode
Insufficient current to melt the wire off cleanly
1/4 inch to 1/2 inch

12. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
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V groove or U groove
When the filler wire is in direct contract with the base metal
20 to 200 times per second

13. Give a description of 'pinch effect'
Spatter problems and poor weld appearance
Duty cycle
When the filler wire is in direct contract with the base metal
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

14. In the GMAW process what does voltage control?
These terms are quite restrictive and often technically incorrect
Puddle fluidity
Motor driven generators - Transformer rectifiers - and Inverter designs
Reducing the gas source pressure to a constant working pressure

15. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
Constant voltage (CV)
The resistace to electrical current flow increases with it. Causing the electrode to heat
...

16. What is the preferred drive roll design for solid wires?
15 feet (4.5 meters)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
1/4 inch to 1/2 inch
V groove or U groove

17. How many times per second does short circuiting take place?
These terms are quite restrictive and often technically incorrect
Higher 26 to 35 arc volts
20 to 200 times per second
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18. What is the required arc voltage used for short circuit transfer?
Controls the rate of flow of a shielding gas to the gun nozzle
Penetration and burn - off rate of the electrode
12 to 22 arc volts
By there current carrying capacity

19. What power sources are used with the GMAW Process?
1/4 inch to 1/2 inch
Motor driven generators - Transformer rectifiers - and Inverter designs
Puddle fluidity
V groove or U groove

20. What is the purpose of the shielding gas used in GMAW?
To prevent leakage - Carbon Dioxide (CO2)
Shielding the molten weld metal from atmospheric contamination
V groove or U groove
Reducing the gas source pressure to a constant working pressure

21. What 2 controls are found on a GMAW set- up?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Wire feeds smoothly (yet will slip should a problem occur in the gun)
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
Wire feed speed - Voltage control

22. List several industries that would use GMAW
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Penetration and burn - off rate of the electrode
Pressure vessels and the piping industry
Constant- speed wire feeders and Voltage- sennsing wire feeders

23. What does a flowmeter do and what does it measure?
By there current carrying capacity
Penetration and burn - off rate of the electrode
Controls the rate of flow of a shielding gas to the gun nozzle
Minutes of elapsed time continually run (out of 10 minutes)

24. What does the wire feeder control?
The negative side of a welding unit
Constant- speed wire feeders and Voltage- sennsing wire feeders
Speed of the feed motor and - starting / stopping electrode feed
Pressure - The rate of flow of a shielding gas

25. What does inductance control?
The time rate of response for the current rise and fall
Shielding the molten weld metal from atmospheric contamination
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Pressure - The rate of flow of a shielding gas

26. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
The negative side of a welding unit
SMAW - GTAW
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

27. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
AWS and CSA
20 to 200 times per second
Higher 26 to 35 arc volts

28. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
To limit the short circuiting current so that spatter is reduced
(DCEP) Direct Current Electrode Positive or Reverse polarity
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

29. What is a solenoid valve and what actuates it?
Constant current (CC)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
The time rate of response for the current rise and fall
DCEP (Direct Current Electrode Positive) Reverse Polarity

30. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
Shielding the molten weld metal from atmospheric contamination
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Duty cycle

31. What type of power source is commonly used with a voltage sensing wire feeder?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Constant current (CC)
AWS and CSA
Constant- speed wire feeders and Voltage- sennsing wire feeders

32. What 2 organizations designate specifications for GMAW wires?
Motor driven generators - Transformer rectifiers - and Inverter designs
AWS and CSA
5.8 to 12.5 L/min
Constant current (CC)

33. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
SMAW - GTAW
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Minutes of elapsed time continually run (out of 10 minutes)

34. What does the term GMAW identify?
Gas metal arc welding
Controls the rate of flow of a shielding gas to the gun nozzle
Higher 26 to 35 arc volts
When the filler wire is in direct contract with the base metal

35. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
Reducing the gas source pressure to a constant working pressure
15 feet (4.5 meters)
The time rate of response for the current rise and fall

36. How are GMAW guns rated?
By there current carrying capacity
Reducing the gas source pressure to a constant working pressure
Gas metal arc welding
Pressure vessels and the piping industry

37. What wire are knurled drive rolls most commonly used on?
To prevent leakage - Carbon Dioxide (CO2)
Flux cored wires
By there current carrying capacity
Insufficient current to melt the wire off cleanly

38. What processes are constant current (CC) power sources designed to be used with?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Spatter problems and poor weld appearance
SMAW - GTAW
When the filler wire is in direct contract with the base metal

39. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
The time rate of response for the current rise and fall
Higher 26 to 35 arc volts
...
Duty cycle

40. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Insufficient current to melt the wire off cleanly
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

41. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
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
12 to 22 arc volts

42. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
Gives arc voltage values to the control system of the feeder
(DCEP) Direct Current Electrode Positive or Reverse polarity
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

43. What controls amperage when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
15 feet (4.5 meters)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Wire feed speed

44. A pull type drive system is usually used on what type of material?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Aluminum wire
The resistace to electrical current flow increases with it. Causing the electrode to heat
Constant- speed wire feeders and Voltage- sennsing wire feeders

45. What happens when the electrode extension is increased?
Flux cored wires
The resistace to electrical current flow increases with it. Causing the electrode to heat
Wire feed speed
85%

46. List 3 forms compressed gases may be supplied for welding
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
To limit the short circuiting current so that spatter is reduced
Motor driven generators - Transformer rectifiers - and Inverter designs
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

47. What is the purpose of a regulator and what does it indicate on its gauges?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Insufficient current to melt the wire off cleanly
Reducing the gas source pressure to a constant working pressure
Constant current (CC)

48. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Constant voltage (CV)
The negative side of a welding unit
Duty cycle
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49. When is the metal transferred with short circuit transfer?
When the filler wire is in direct contract with the base metal
Welding process that joins metals by heating them with an electric arc
Short- circuiting transfer - Globular transfer - Spray transfer
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

50. What effect does increasing and decreasing the inductance have on the weld?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
DCEP (Direct Current Electrode Positive) Reverse Polarity
These terms are quite restrictive and often technically incorrect