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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. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
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
Wire feed speed

2. List 3 forms compressed gases may be supplied for welding
...
Constant voltage (CV)
Aluminum wire
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

3. What processes are constant current (CC) power sources designed to be used with?
Puddle fluidity
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Cause flaking - which can clog the liner and contact tube
SMAW - GTAW

4. What wire are knurled drive rolls most commonly used on?
Generally not as accurate
Higher 26 to 35 arc volts
Flux cored wires
When the filler wire is in direct contract with the base metal

5. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
To limit the short circuiting current so that spatter is reduced
Controls the rate of flow of a shielding gas to the gun nozzle
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

6. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Duty cycle
Motor driven generators - Transformer rectifiers - and Inverter designs
Reducing the gas source pressure to a constant working pressure

7. A 10 minute cycle of welding time vs cooling time a given machine can handle.
SMAW - GTAW
Duty cycle
Minutes of elapsed time continually run (out of 10 minutes)
Puddle fluidity

8. What is the required arc voltage used for short circuit transfer?
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
12 to 22 arc volts
Duty cycle

9. List the factors that determine the mode of metal transfer
Minutes of elapsed time continually run (out of 10 minutes)
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
The resistace to electrical current flow increases with it. Causing the electrode to heat

10. What is a solenoid valve and what actuates it?
National Electrical Manufactures Association
V groove or U groove
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on 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

11. 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
Puddle fluidity
The time rate of response for the current rise and fall
12 to 22 arc volts

12. How many times per second does short circuiting take place?
Wire feed speed
20 to 200 times per second
Minimum distortion due to low heat input
Generally not as accurate

13. What does inductance control?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Spatter problems and poor weld appearance
The time rate of response for the current rise and fall

14. What does the wire feeder control?
Wire feed speed - Voltage control
Speed of the feed motor and - starting / stopping electrode feed
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Cause flaking - which can clog the liner and contact tube

15. A pull type drive system is usually used on what type of material?
Gas metal arc welding
Aluminum wire
Speed of the feed motor and - starting / stopping electrode feed
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

16. Give a brief description of the GMAW process
15 feet (4.5 meters)
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Guns
Welding process that joins metals by heating them with an electric arc

17. In the GMAW process what does voltage control?
Puddle fluidity
The time rate of response for the current rise and fall
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Short- circuiting transfer - Globular transfer - Spray transfer

18. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
Aluminum wire
These terms are quite restrictive and often technically incorrect
Puddle fluidity

19. What does the abbreviation NEMA stand for?
Shielding the molten weld metal from atmospheric contamination
Constant current (CC)
DCEP (Direct Current Electrode Positive) Reverse Polarity
National Electrical Manufactures Association

20. What is the effect of too much slope?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Insufficient current to melt the wire off cleanly
(DCEP) Direct Current Electrode Positive or Reverse polarity
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21. Why is the term GMAW preferred over MIG or MAG?
Gas metal arc welding
These terms are quite restrictive and often technically incorrect
If you dont know this check your phone
Welding process that joins metals by heating them with an electric arc

22. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Minutes of elapsed time continually run (out of 10 minutes)
Wire feeds smoothly (yet will slip should a problem occur in the gun)
(DCEP) Direct Current Electrode Positive or Reverse polarity
Constant current (CC)

23. 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
5.8 to 12.5 L/min
3
...

24. With straight polarity where is 2/3 of the arc energy?
Guns
Constant- speed wire feeders and Voltage- sennsing wire feeders
The negative side of a welding unit
Aluminum wire

25. List several industries that would use GMAW
The Arc voltage
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Pressure vessels and the piping industry
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

26. What 2 organizations designate specifications for GMAW wires?
SMAW - GTAW
Insufficient current to melt the wire off cleanly
Wire feeds smoothly (yet will slip should a problem occur in the gun)
AWS and CSA

27. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
Wire feed speed - Voltage control
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Flux cored wires

28. In the GMAW process what does amperage control?
Shielding the molten weld metal from atmospheric contamination
Dry ice can form within the flow control openings and cause blockage of shielding gas
Penetration and burn - off rate of the electrode
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

29. What is a typical flow rate of CO2 for short circuit transfer?
Pressure - The rate of flow of a shielding gas
Flux cored wires
5.8 to 12.5 L/min
Insufficient current to melt the wire off cleanly

30. Draw a typical volt amp curve for a machine that is designed for GMAW
The negative side of a welding unit
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Motor driven generators - Transformer rectifiers - and Inverter designs
Penetration and burn - off rate of the electrode

31. Regulators control_____________ flowmeters SHOW____________.
20 to 200 times per second
5.8 to 12.5 L/min
Pressure - The rate of flow of a shielding gas
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

32. When is the metal transferred with short circuit transfer?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Aluminum wire
When the filler wire is in direct contract with the base metal
Insufficient current to melt the wire off cleanly

33. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Cause flaking - which can clog the liner and contact tube
Welding process that joins metals by heating them with an electric arc
Gas metal arc welding
Controls the rate of flow of a shielding gas to the gun nozzle

34. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Short- circuiting transfer - Globular transfer - Spray transfer
To limit the short circuiting current so that spatter is reduced
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

35. What is the purpose of the shielding gas used in GMAW?
Voltage is the force that overcomes resistance to allow amperage flow
Controls the rate of flow of a shielding gas to the gun nozzle
Shielding the molten weld metal from atmospheric contamination
Minimum distortion due to low heat input

36. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Constant voltage (CV)
Voltage is the force that overcomes resistance to allow amperage flow
SMAW - GTAW

37. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
To prevent drawing of liquid CO2 (Carbon Dioxide)
Aluminum wire
The time rate of response for the current rise and fall

38. 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
85%
These terms are quite restrictive and often technically incorrect

39. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
By there current carrying capacity
Flux cored wires
Shielding the molten weld metal from atmospheric contamination

40. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
Puddle fluidity
Aluminum wire
Gas metal arc welding

41. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
AWS and CSA
85%
Guns
Speed of the feed motor and - starting / stopping electrode feed

42. What is another term for electrode holders for GMAW?
To prevent leakage - Carbon Dioxide (CO2)
Guns
Minimum distortion due to low heat input
5.8 to 12.5 L/min

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

44. What controls amperage when using GMAW?
The negative side of a welding unit
Wire feed speed
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
...

45. What does voltage do in an electrical circuit?
Minimum distortion due to low heat input
Voltage is the force that overcomes resistance to allow amperage flow
Pressure vessels and the piping industry
Welding process that joins metals by heating them with an electric arc

46. What is the key advantage of short circuiting transfer?
5.8 to 12.5 L/min
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Minimum distortion due to low heat input
V groove or U groove

47. 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
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
These terms are quite restrictive and often technically incorrect

48. What type of power source is commonly used with a voltage sensing wire feeder?
Penetration and burn - off rate of the electrode
To prevent leakage - Carbon Dioxide (CO2)
Generally not as accurate
Constant current (CC)

49. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
5.8 to 12.5 L/min
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Dry ice can form within the flow control openings and cause blockage of shielding gas

50. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
...
Short- circuiting transfer - Globular transfer - Spray transfer
DCEP (Direct Current Electrode Positive) Reverse Polarity
The Arc voltage