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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.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

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. Give a description of 'pinch effect'
Minutes of elapsed time continually run (out of 10 minutes)
Duty cycle
Flux cored wires
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

2. Draw a typical volt amp curve for a machine that is designed for GMAW
The time rate of response for the current rise and fall
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
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3. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Insufficient current to melt the wire off cleanly
If you dont know this check your phone
Flux cored wires
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

4. How many times per second does short circuiting take place?
Cause flaking - which can clog the liner and contact tube
20 to 200 times per second
Speed of the feed motor and - starting / stopping electrode feed
Wire feed speed - Voltage control

5. 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
To prevent drawing of liquid CO2 (Carbon Dioxide)
Aluminum wire
These terms are quite restrictive and often technically incorrect

6. 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
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Higher 26 to 35 arc volts
Constant- speed wire feeders and Voltage- sennsing wire feeders

7. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Guns
(DCEP) Direct Current Electrode Positive or Reverse polarity
To limit the short circuiting current so that spatter is reduced
Cause flaking - which can clog the liner and contact tube

8. What is a solenoid valve and what actuates it?
Spatter problems and poor weld appearance
Aluminum wire
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
5.8 to 12.5 L/min

9. What wire are knurled drive rolls most commonly used on?
3
When the filler wire is in direct contract with the base metal
Duty cycle
Flux cored wires

10. What is the preferred drive roll design for solid wires?
V groove or U groove
To limit the short circuiting current so that spatter is reduced
20 to 200 times per second
DCEP (Direct Current Electrode Positive) Reverse Polarity

11. When is the metal transferred with short circuit transfer?
...
Cause flaking - which can clog the liner and contact tube
Gives arc voltage values to the control system of the feeder
When the filler wire is in direct contract with the base metal

12. What does the abbreviation NEMA stand for?
SMAW - GTAW
Gas metal arc welding
Cause flaking - which can clog the liner and contact tube
National Electrical Manufactures Association

13. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Aluminum wire
Generally not as accurate
The Arc voltage

14. What is another term for electrode holders for GMAW?
Guns
Reducing the gas source pressure to a constant working pressure
To prevent drawing of liquid CO2 (Carbon Dioxide)
SMAW - GTAW

15. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Spatter problems and poor weld appearance
85%
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
V groove or U groove

16. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
Gas metal arc welding
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Insufficient current to melt the wire off cleanly

17. What controls amperage when using GMAW?
Gives arc voltage values to the control system of the feeder
Wire feed speed
Motor driven generators - Transformer rectifiers - and Inverter designs
Guns

18. What does the wire feeder control?
Speed of the feed motor and - starting / stopping electrode feed
SMAW - GTAW
Penetration and burn - off rate of the electrode
Welding process that joins metals by heating them with an electric arc

19. List 3 wire drive systems and give a short description of each
Cause flaking - which can clog the liner and contact tube
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
AWS and CSA
V groove or U groove

20. A 10 minute cycle of welding time vs cooling time a given machine can handle.
The time rate of response for the current rise and fall
SMAW - GTAW
Duty cycle
...

21. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
The Arc voltage
Wire feed speed - Voltage control
Constant voltage (CV)

22. What is the disadvantage of the gauge preset type of regulator/flowmeter?
When the filler wire is in direct contract with the base metal
Generally not as accurate
...
15 feet (4.5 meters)

23. What is the effect of too much slope?
The negative side of a welding unit
Insufficient current to melt the wire off cleanly
85%
Controls the rate of flow of a shielding gas to the gun nozzle

24. What does voltage do in an electrical circuit?
The Arc voltage
Constant current (CC)
Voltage is the force that overcomes resistance to allow amperage flow
Duty cycle

25. In the GMAW process what does voltage control?
...
Constant voltage (CV)
National Electrical Manufactures Association
Puddle fluidity

26. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
Spatter problems and poor weld appearance
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
SMAW - GTAW

27. What is the purpose of a regulator and what does it indicate on its gauges?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Reducing the gas source pressure to a constant working pressure
Minimum distortion due to low heat input
Puddle fluidity

28. Regulators control_____________ flowmeters SHOW____________.
85%
Pressure - The rate of flow of a shielding gas
To prevent drawing of liquid CO2 (Carbon Dioxide)
These terms are quite restrictive and often technically incorrect

29. What 2 organizations designate specifications for GMAW wires?
Pressure - The rate of flow of a shielding gas
AWS and CSA
Motor driven generators - Transformer rectifiers - and Inverter designs
Insufficient current to melt the wire off cleanly

30. What is the recommended electrode stick- out for .035 solid wire?
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
1/4 inch to 1/2 inch
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

31. Why must CO2 cylinders be used in the vertical position?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Gives arc voltage values to the control system of the feeder
To prevent drawing of liquid CO2 (Carbon Dioxide)

32. List the factors that determine the mode of metal transfer
V groove or U groove
5.8 to 12.5 L/min
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Generally not as accurate

33. List 3 forms compressed gases may be supplied for welding
1/4 inch to 1/2 inch
Cause flaking - which can clog the liner and contact tube
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Guns

34. A pull type drive system is usually used on what type of material?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Aluminum wire
5.8 to 12.5 L/min
...

35. What is the maximum distance that hard wire can be successfully pushed?
The negative side of a welding unit
15 feet (4.5 meters)
Aluminum wire
Wire feeds smoothly (yet will slip should a problem occur in the gun)

36. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
National Electrical Manufactures Association
AWS and CSA
Gives arc voltage values to the control system of the feeder
Voltage is the force that overcomes resistance to allow amperage flow

37. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Gives arc voltage values to the control system of the feeder
...
3
12 to 22 arc volts

38. What does the term GMAW identify?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Wire feed speed
Gas metal arc welding
12 to 22 arc volts

39. List several industries that would use GMAW
To prevent drawing of liquid CO2 (Carbon Dioxide)
Shielding the molten weld metal from atmospheric contamination
Pressure vessels and the piping industry
5.8 to 12.5 L/min

40. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
V groove or U groove
...
(DCEP) Direct Current Electrode Positive or Reverse polarity
Insufficient current to melt the wire off cleanly

41. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
SMAW - GTAW
To prevent drawing of liquid CO2 (Carbon Dioxide)
Wire feeds smoothly (yet will slip should a problem occur in the gun)

42. What is the required arc voltage used for short circuit transfer?
20 to 200 times per second
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Minutes of elapsed time continually run (out of 10 minutes)
12 to 22 arc volts

43. What is the purpose of the shielding gas used in GMAW?
Insufficient current to melt the wire off cleanly
The resistace to electrical current flow increases with it. Causing the electrode to heat
Speed of the feed motor and - starting / stopping electrode feed
Shielding the molten weld metal from atmospheric contamination

44. Why is a line heater required when using GMAW?
15 feet (4.5 meters)
Pressure vessels and the piping industry
Dry ice can form within the flow control openings and cause blockage of shielding gas
The negative side of a welding unit

45. 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
Puddle fluidity
Duty cycle
If you dont know this check your phone

46. Why is globular transfer generally avoided with GMAW?
20 to 200 times per second
Penetration and burn - off rate of the electrode
To prevent leakage - Carbon Dioxide (CO2)
Spatter problems and poor weld appearance

47. In the GMAW process what does amperage control?
Puddle fluidity
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
AWS and CSA
Penetration and burn - off rate of the electrode

48. What does inductance control?
The time rate of response for the current rise and fall
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
The negative side of a welding unit

49. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
Controls the rate of flow of a shielding gas to the gun nozzle
To limit the short circuiting current so that spatter is reduced
3

50. What processes are constant current (CC) power sources designed to be used with?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
SMAW - GTAW
Controls the rate of flow of a shielding gas to the gun nozzle
Duty cycle