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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. What is the key advantage of short circuiting transfer?
Reducing the gas source pressure to a constant working pressure
Minimum distortion due to low heat input
Higher 26 to 35 arc volts
Controls the rate of flow of a shielding gas to the gun nozzle

2. List several industries that would use GMAW
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
3
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Pressure vessels and the piping industry

3. What does the abbreviation NEMA stand for?
3
National Electrical Manufactures Association
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Wire feed speed - Voltage control

4. In the GMAW process what does voltage control?
AWS and CSA
SMAW - GTAW
Reducing the gas source pressure to a constant working pressure
Puddle fluidity

5. What is the required arc voltage used for short circuit transfer?
12 to 22 arc volts
Constant current (CC)
Constant- speed wire feeders and Voltage- sennsing wire feeders
(DCEP) Direct Current Electrode Positive or Reverse polarity

6. In the GMAW process what does amperage control?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
12 to 22 arc volts
When the filler wire is in direct contract with the base metal
Penetration and burn - off rate of the electrode

7. What is an advantage of pulsed arc transfer with GMAW?
Shielding the molten weld metal from atmospheric contamination
Gas metal arc welding
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
By there current carrying capacity

8. What is the purpose of a regulator and what does it indicate on its gauges?
85%
Reducing the gas source pressure to a constant working pressure
Voltage is the force that overcomes resistance to allow amperage flow
Pressure - The rate of flow of a shielding gas

9. What does the term GMAW identify?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Gas metal arc welding
Constant current (CC)
To prevent drawing of liquid CO2 (Carbon Dioxide)

10. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
Reducing the gas source pressure to a constant working pressure
Insufficient current to melt the wire off cleanly
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

11. What output on the welding machine is used to rate the duty cycle?
Minutes of elapsed time continually run (out of 10 minutes)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Wire feeds smoothly (yet will slip should a problem occur in the gun)
The Arc voltage

12. Why is globular transfer generally avoided with GMAW?
85%
Spatter problems and poor weld appearance
...
These terms are quite restrictive and often technically incorrect

13. What controls the wire speed on a voltage sensing wire feeder?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
The Arc voltage
AWS and CSA
To prevent leakage - Carbon Dioxide (CO2)

14. List the factors that determine the mode of metal transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Generally not as accurate
National Electrical Manufactures Association
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

15. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Pressure vessels and the piping industry
Minimum distortion due to low heat input
The resistace to electrical current flow increases with it. Causing the electrode to heat
(DCEP) Direct Current Electrode Positive or Reverse polarity

16. What is the disadvantage of the gauge preset type of regulator/flowmeter?
20 to 200 times per second
The Arc voltage
Constant- speed wire feeders and Voltage- sennsing wire feeders
Generally not as accurate

17. List the basic equipment requirements for the GMAW process
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Pressure - The rate of flow of a shielding gas
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Guns

18. What does inductance control?
Dry ice can form within the flow control openings and cause blockage of shielding gas
The time rate of response for the current rise and fall
Generally not as accurate
Duty cycle

19. What is the preferred drive roll design for solid wires?
V groove or U groove
If you dont know this check your phone
DCEP (Direct Current Electrode Positive) Reverse Polarity
Reducing the gas source pressure to a constant working pressure

20. What wire are knurled drive rolls most commonly used on?
Flux cored wires
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
The time rate of response for the current rise and fall
Constant- speed wire feeders and Voltage- sennsing wire feeders

21. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Motor driven generators - Transformer rectifiers - and Inverter designs
AWS and CSA
3

22. What is the recommended electrode stick- out for .035 solid wire?
Insufficient current to melt the wire off cleanly
These terms are quite restrictive and often technically incorrect
Penetration and burn - off rate of the electrode
1/4 inch to 1/2 inch

23. What is another term for electrode holders for GMAW?
Spatter problems and poor weld appearance
Flux cored wires
Guns
To limit the short circuiting current so that spatter is reduced

24. What type of power source is used with a constant speed wire feeder?
3
Constant voltage (CV)
85%
Aluminum wire

25. What would be an indication that the drive roll pressure is adjusted correctly?
Flux cored wires
Wire feeds smoothly (yet will slip should a problem occur in the gun)
The Arc voltage
Short- circuiting transfer - Globular transfer - Spray transfer

26. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
1/4 inch to 1/2 inch
The negative side of a welding unit
The resistace to electrical current flow increases with it. Causing the electrode to heat

27. What controls amperage when using GMAW?
Wire feed speed
The resistace to electrical current flow increases with it. Causing the electrode to heat
Flux cored wires
If you dont know this check your phone

28. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
When the filler wire is in direct contract with the base metal
Cause flaking - which can clog the liner and contact tube
If you dont know this check your phone
To prevent drawing of liquid CO2 (Carbon Dioxide)

29. Why must CO2 cylinders be used in the vertical position?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
To prevent drawing of liquid CO2 (Carbon Dioxide)
Motor driven generators - Transformer rectifiers - and Inverter designs
National Electrical Manufactures Association

30. What type of power source is commonly used with a voltage sensing wire feeder?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Duty cycle
Constant current (CC)
Welding process that joins metals by heating them with an electric arc

31. Regulators control_____________ flowmeters SHOW____________.
DCEP (Direct Current Electrode Positive) Reverse Polarity
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Pressure - The rate of flow of a shielding gas
Flux cored wires

32. List the three methods of metal transfer with GMAW
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Short- circuiting transfer - Globular transfer - Spray transfer
Generally not as accurate
Flux cored wires

33. Give a description of 'pinch effect'
Reducing the gas source pressure to a constant working pressure
Welding process that joins metals by heating them with an electric arc
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Gives arc voltage values to the control system of the feeder

34. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
Pressure vessels and the piping industry
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
If you dont know this check your phone

35. What are the 2 types of wire feeders available?
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
Wire feed speed - Voltage control
20 to 200 times per second

36. What power sources are used with the GMAW Process?
The resistace to electrical current flow increases with it. Causing the electrode to heat
The Arc voltage
Duty cycle
Motor driven generators - Transformer rectifiers - and Inverter designs

37. 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
Guns
National Electrical Manufactures Association

38. A pull type drive system is usually used on what type of material?
When the filler wire is in direct contract with the base metal
Aluminum wire
Speed of the feed motor and - starting / stopping electrode feed
Constant current (CC)

39. What is the effect of too much slope?
The Arc voltage
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
AWS and CSA
Insufficient current to melt the wire off cleanly

40. 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
Insufficient current to melt the wire off cleanly
If you dont know this check your phone

41. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Minutes of elapsed time continually run (out of 10 minutes)
Gives arc voltage values to the control system of the feeder
1/4 inch to 1/2 inch
Duty cycle

42. Why is the term GMAW preferred over MIG or MAG?
Pressure vessels and the piping industry
By there current carrying capacity
These terms are quite restrictive and often technically incorrect
The time rate of response for the current rise and fall

43. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
Higher 26 to 35 arc volts
85%
DCEP (Direct Current Electrode Positive) Reverse Polarity

44. How many times per second does short circuiting take place?
Aluminum wire
20 to 200 times per second
The resistace to electrical current flow increases with it. Causing the electrode to heat
To prevent leakage - Carbon Dioxide (CO2)

45. What is a typical flow rate of CO2 for short circuit transfer?
Short- circuiting transfer - Globular transfer - Spray transfer
5.8 to 12.5 L/min
DCEP (Direct Current Electrode Positive) Reverse Polarity
Constant voltage (CV)

46. What 2 organizations designate specifications for GMAW wires?
DCEP (Direct Current Electrode Positive) Reverse Polarity
AWS and CSA
3
15 feet (4.5 meters)

47. Draw a typical volt amp curve for a machine that is designed for GMAW
To prevent leakage - Carbon Dioxide (CO2)
Duty cycle
Constant- speed wire feeders and Voltage- sennsing wire feeders
If you dont know this check your phone

48. Give a brief description of the GMAW process
To prevent drawing of liquid CO2 (Carbon Dioxide)
3
Welding process that joins metals by heating them with an electric arc
Duty cycle

49. List 3 wire drive systems and give a short description of each
12 to 22 arc volts
Generally not as accurate
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
Aluminum wire

50. How are GMAW guns rated?
By there current carrying capacity
The Arc voltage
Duty cycle
Constant- speed wire feeders and Voltage- sennsing wire feeders