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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 happens when the electrode extension is increased?
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
DCEP (Direct Current Electrode Positive) Reverse Polarity
20 to 200 times per second
The resistace to electrical current flow increases with it. Causing the electrode to heat

2. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
Pressure - The rate of flow of a shielding gas
Pressure vessels and the piping industry
Motor driven generators - Transformer rectifiers - and Inverter designs

3. List the factors that determine the mode of metal transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
DCEP (Direct Current Electrode Positive) Reverse Polarity
Insufficient current to melt the wire off cleanly
Aluminum wire

4. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
These terms are quite restrictive and often technically incorrect
Flux cored wires
Gives arc voltage values to the control system of the feeder
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

5. List the three methods of metal transfer with GMAW
Dry ice can form within the flow control openings and cause blockage of shielding gas
3
Welding process that joins metals by heating them with an electric arc
Short- circuiting transfer - Globular transfer - Spray transfer

6. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Wire feed speed
Generally not as accurate
To prevent leakage - Carbon Dioxide (CO2)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

7. What effect does increasing and decreasing the inductance have on the weld?
Welding process that joins metals by heating them with an electric arc
These terms are quite restrictive and often technically incorrect
Penetration and burn - off rate of the electrode
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

8. 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
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Spatter problems and poor weld appearance
Penetration and burn - off rate of the electrode

9. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
Puddle fluidity
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Minutes of elapsed time continually run (out of 10 minutes)

10. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
Speed of the feed motor and - starting / stopping electrode feed
When the filler wire is in direct contract with the base metal
Wire feeds smoothly (yet will slip should a problem occur in the gun)

11. Draw a typical volt amp curve for a machine that is designed for GMAW
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
If you dont know this check your phone
Insufficient current to melt the wire off cleanly

12. What 2 organizations designate specifications for GMAW wires?
Pressure vessels and the piping industry
AWS and CSA
15 feet (4.5 meters)
1/4 inch to 1/2 inch

13. What is the main purpose of 'slope'?
To prevent leakage - Carbon Dioxide (CO2)
Controls the rate of flow of a shielding gas to the gun nozzle
Wire feed speed
To limit the short circuiting current so that spatter is reduced

14. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Generally not as accurate
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
85%
(DCEP) Direct Current Electrode Positive or Reverse polarity

15. What does the wire feeder control?
Speed of the feed motor and - starting / stopping electrode feed
Controls the rate of flow of a shielding gas to the gun nozzle
Guns
If you dont know this check your phone

16. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Flux cored wires
Reducing the gas source pressure to a constant working pressure

17. List 3 forms compressed gases may be supplied for welding
Wire feed speed - Voltage control
Constant- speed wire feeders and Voltage- sennsing wire feeders
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
DCEP (Direct Current Electrode Positive) Reverse Polarity

18. What is the preferred drive roll design for solid wires?
12 to 22 arc volts
Voltage is the force that overcomes resistance to allow amperage flow
V groove or U groove
These terms are quite restrictive and often technically incorrect

19. How many times per second does short circuiting take place?
DCEP (Direct Current Electrode Positive) Reverse Polarity
20 to 200 times per second
Penetration and burn - off rate of the electrode
National Electrical Manufactures Association

20. Regulators control_____________ flowmeters SHOW____________.
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Pressure - The rate of flow of a shielding gas
Duty cycle
Pressure vessels and the piping industry

21. What is another term for electrode holders for GMAW?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
The Arc voltage
Flux cored wires
Guns

22. Why is a fiber washer required and what cylinder gas requires it?
15 feet (4.5 meters)
To prevent leakage - Carbon Dioxide (CO2)
The resistace to electrical current flow increases with it. Causing the electrode to heat
National Electrical Manufactures Association

23. What is a solenoid valve and what actuates it?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Guns
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
1/4 inch to 1/2 inch

24. 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
...
Higher 26 to 35 arc volts
(DCEP) Direct Current Electrode Positive or Reverse polarity

25. What 2 controls are found on a GMAW set- up?
Aluminum wire
Wire feed speed - Voltage control
To prevent drawing of liquid CO2 (Carbon Dioxide)
85%

26. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
...
National Electrical Manufactures Association
Controls the rate of flow of a shielding gas to the gun nozzle

27. List the basic equipment requirements for the GMAW process
12 to 22 arc volts
85%
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
To prevent drawing of liquid CO2 (Carbon Dioxide)

28. What output on the welding machine is used to rate the duty cycle?
Minutes of elapsed time continually run (out of 10 minutes)
...
Pressure - The rate of flow of a shielding gas
Gives arc voltage values to the control system of the feeder

29. What does the term GMAW identify?
Gas metal arc welding
85%
To prevent drawing of liquid CO2 (Carbon Dioxide)
The Arc voltage

30. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Voltage is the force that overcomes resistance to allow amperage flow
If you dont know this check your phone
3
AWS and CSA

31. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
If you dont know this check your phone
3
SMAW - GTAW
Insufficient current to melt the wire off cleanly

32. Why is a line heater required when using GMAW?
Spatter problems and poor weld appearance
Cause flaking - which can clog the liner and contact tube
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

33. A pull type drive system is usually used on what type of material?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Aluminum wire
DCEP (Direct Current Electrode Positive) Reverse Polarity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

34. Give a brief description of the GMAW process
1/4 inch to 1/2 inch
Constant voltage (CV)
Welding process that joins metals by heating them with an electric arc
If you dont know this check your phone

35. What type of power source is commonly used with a voltage sensing wire feeder?
Constant current (CC)
Welding process that joins metals by heating them with an electric arc
...
To prevent drawing of liquid CO2 (Carbon Dioxide)

36. What controls amperage when using GMAW?
Wire feed speed
15 feet (4.5 meters)
DCEP (Direct Current Electrode Positive) Reverse Polarity
Reducing the gas source pressure to a constant working pressure

37. How are GMAW guns rated?
Motor driven generators - Transformer rectifiers - and Inverter designs
Shielding the molten weld metal from atmospheric contamination
12 to 22 arc volts
By there current carrying capacity

38. Why is the term GMAW preferred over MIG or MAG?
Higher 26 to 35 arc volts
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
These terms are quite restrictive and often technically incorrect

39. When is the metal transferred with short circuit transfer?
Wire feed speed - Voltage control
Shielding the molten weld metal from atmospheric contamination
When the filler wire is in direct contract with the base metal
Minutes of elapsed time continually run (out of 10 minutes)

40. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Voltage is the force that overcomes resistance to allow amperage flow
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
...

41. What does inductance control?
The time rate of response for the current rise and fall
(DCEP) Direct Current Electrode Positive or Reverse polarity
Gas metal arc welding
Constant current (CC)

42. What are the 2 types of wire feeders available?
Controls the rate of flow of a shielding gas to the gun nozzle
Constant- speed wire feeders and Voltage- sennsing wire feeders
Flux cored wires
12 to 22 arc volts

43. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
Constant current (CC)
Shielding the molten weld metal from atmospheric contamination
Minimum distortion due to low heat input

44. What does a flowmeter do and what does it measure?
Duty cycle
Spatter problems and poor weld appearance
Controls the rate of flow of a shielding gas to the gun nozzle
Shielding the molten weld metal from atmospheric contamination

45. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Wire feed speed
Pressure - The rate of flow of a shielding gas
85%
15 feet (4.5 meters)

46. With straight polarity where is 2/3 of the arc energy?
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
The negative side of a welding unit
Spatter problems and poor weld appearance

47. Why must CO2 cylinders be used in the vertical position?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Duty cycle
To prevent drawing of liquid CO2 (Carbon Dioxide)
When the filler wire is in direct contract with the base metal

48. What type of power source is used with a constant speed wire feeder?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Constant voltage (CV)
To prevent leakage - Carbon Dioxide (CO2)
Gas metal arc welding

49. What is a typical flow rate of CO2 for short circuit transfer?
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5.8 to 12.5 L/min
Reducing the gas source pressure to a constant working pressure
...

50. What is the maximum distance that hard wire can be successfully pushed?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
15 feet (4.5 meters)
The Arc voltage
20 to 200 times per second