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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 controls amperage when using GMAW?
Wire feed speed
SMAW - GTAW
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Gives arc voltage values to the control system of the feeder

2. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
Gives arc voltage values to the control system of the feeder
To limit the short circuiting current so that spatter is reduced
1/4 inch to 1/2 inch

3. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
Minimum distortion due to low heat input
Duty cycle
15 feet (4.5 meters)

4. What power sources are used with the GMAW Process?
Reducing the gas source pressure to a constant working pressure
Motor driven generators - Transformer rectifiers - and Inverter designs
If you dont know this check your phone
By there current carrying capacity

5. What wire are knurled drive rolls most commonly used on?
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
Aluminum wire
To prevent leakage - Carbon Dioxide (CO2)

6. With straight polarity where is 2/3 of the arc energy?
Guns
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
The negative side of a welding unit
Dry ice can form within the flow control openings and cause blockage of shielding gas

7. What type of power source is commonly used with a voltage sensing wire feeder?
Constant current (CC)
Motor driven generators - Transformer rectifiers - and Inverter designs
12 to 22 arc volts
5.8 to 12.5 L/min

8. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
DCEP (Direct Current Electrode Positive) Reverse Polarity
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

9. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
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85%
AWS and CSA
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

10. List 3 wire drive systems and give a short description of each
The time rate of response for the current rise and fall
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
To prevent drawing of liquid CO2 (Carbon Dioxide)
Motor driven generators - Transformer rectifiers - and Inverter designs

11. What is the required arc voltage used for short circuit transfer?
(DCEP) Direct Current Electrode Positive or Reverse polarity
12 to 22 arc volts
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Puddle fluidity

12. What would be an indication that the drive roll pressure is adjusted correctly?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
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
1/4 inch to 1/2 inch

13. What does the abbreviation NEMA stand for?
V groove or U groove
Reducing the gas source pressure to a constant working pressure
85%
National Electrical Manufactures Association

14. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
These terms are quite restrictive and often technically incorrect
Gives arc voltage values to the control system of the feeder
Flux cored wires
Reducing the gas source pressure to a constant working pressure

15. What is the recommended electrode stick- out for .035 solid wire?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
1/4 inch to 1/2 inch
Wire feed speed
15 feet (4.5 meters)

16. What is the maximum distance that hard wire can be successfully pushed?
Wire feed speed - Voltage control
15 feet (4.5 meters)
Motor driven generators - Transformer rectifiers - and Inverter designs
Higher 26 to 35 arc volts

17. What is the preferred drive roll design for solid wires?
By there current carrying capacity
5.8 to 12.5 L/min
V groove or U groove
Reducing the gas source pressure to a constant working pressure

18. List the three methods of metal transfer with GMAW
Wire feed speed
(DCEP) Direct Current Electrode Positive or Reverse polarity
Short- circuiting transfer - Globular transfer - Spray transfer
Shielding the molten weld metal from atmospheric contamination

19. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
To prevent leakage - Carbon Dioxide (CO2)
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

20. What is the effect of too much slope?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Insufficient current to melt the wire off cleanly
To prevent drawing of liquid CO2 (Carbon Dioxide)
These terms are quite restrictive and often technically incorrect

21. What controls the wire speed on a voltage sensing wire feeder?
12 to 22 arc volts
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
The Arc voltage
Constant voltage (CV)

22. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
3
Spatter problems and poor weld appearance
Insufficient current to melt the wire off cleanly

23. What does the term GMAW identify?
3
Constant voltage (CV)
85%
Gas metal arc welding

24. 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 Arc voltage
Higher 26 to 35 arc volts
The time rate of response for the current rise and fall

25. Give a description of 'pinch effect'
3
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
National Electrical Manufactures Association

26. What type of power source is used with a constant speed wire feeder?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Minutes of elapsed time continually run (out of 10 minutes)
Shielding the molten weld metal from atmospheric contamination
Constant voltage (CV)

27. In the GMAW process what does voltage control?
12 to 22 arc volts
By there current carrying capacity
Puddle fluidity
Generally not as accurate

28. What is a typical flow rate of CO2 for short circuit transfer?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Speed of the feed motor and - starting / stopping electrode feed
Minutes of elapsed time continually run (out of 10 minutes)
5.8 to 12.5 L/min

29. Why is the term GMAW preferred over MIG or MAG?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
If you dont know this check your phone
Aluminum wire
These terms are quite restrictive and often technically incorrect

30. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
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85%
Wire feed speed
Shielding the molten weld metal from atmospheric contamination

31. What happens when the electrode extension is increased?
Gives arc voltage values to the control system of the feeder
Higher 26 to 35 arc volts
The resistace to electrical current flow increases with it. Causing the electrode to heat
The negative side of a welding unit

32. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
V groove or U groove
...
Insufficient current to melt the wire off cleanly
Dry ice can form within the flow control openings and cause blockage of shielding gas

33. List several industries that would use GMAW
Pressure vessels and the piping industry
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
Shielding the molten weld metal from atmospheric contamination
Speed of the feed motor and - starting / stopping electrode feed

34. What output on the welding machine is used to rate the duty cycle?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
The resistace to electrical current flow increases with it. Causing the electrode to heat
Minutes of elapsed time continually run (out of 10 minutes)
Gives arc voltage values to the control system of the feeder

35. How are GMAW guns rated?
1/4 inch to 1/2 inch
Short- circuiting transfer - Globular transfer - Spray transfer
By there current carrying capacity
15 feet (4.5 meters)

36. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
85%
SMAW - GTAW
Aluminum wire

37. Why is a fiber washer required and what cylinder gas requires it?
Pressure vessels and the piping industry
To prevent leakage - Carbon Dioxide (CO2)
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

38. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
Higher 26 to 35 arc volts
If you dont know this check your phone
The Arc voltage

39. What does the wire feeder control?
5.8 to 12.5 L/min
Speed of the feed motor and - starting / stopping electrode feed
The Arc voltage
...

40. When is the metal transferred with short circuit transfer?
If you dont know this check your phone
85%
Pressure - The rate of flow of a shielding gas
When the filler wire is in direct contract with the base metal

41. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
National Electrical Manufactures Association
Constant voltage (CV)
Wire feeds smoothly (yet will slip should a problem occur in the gun)

42. How many times per second does short circuiting take place?
Cause flaking - which can clog the liner and contact tube
Wire feed speed
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
20 to 200 times per second

43. A pull type drive system is usually used on what type of material?
The negative side of a welding unit
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Aluminum wire

44. List the factors that determine the mode of metal transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Guns
Insufficient current to melt the wire off cleanly
Higher 26 to 35 arc volts

45. Draw a typical volt amp curve for a machine that is designed for GMAW
12 to 22 arc volts
Spatter problems and poor weld appearance
Welding process that joins metals by heating them with an electric arc
If you dont know this check your phone

46. Regulators control_____________ flowmeters SHOW____________.
85%
Constant voltage (CV)
Pressure - The rate of flow of a shielding gas
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

47. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Minutes of elapsed time continually run (out of 10 minutes)
Flux cored wires
Generally not as accurate
Dry ice can form within the flow control openings and cause blockage of shielding gas

48. What are the 2 types of wire feeders available?
SMAW - GTAW
Minutes of elapsed time continually run (out of 10 minutes)
Short- circuiting transfer - Globular transfer - Spray transfer
Constant- speed wire feeders and Voltage- sennsing wire feeders

49. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
To prevent leakage - Carbon Dioxide (CO2)
(DCEP) Direct Current Electrode Positive or Reverse polarity
3

50. What 2 organizations designate specifications for GMAW wires?
If you dont know this check your phone
AWS and CSA
SMAW - GTAW
Minimum distortion due to low heat input

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Gas Metal Arc Welding

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