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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 is the required arc voltage used for short circuit transfer?
12 to 22 arc volts
Gas metal arc welding
Shielding the molten weld metal from atmospheric contamination
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

2. What happens when the electrode extension is increased?
12 to 22 arc volts
V groove or U groove
Speed of the feed motor and - starting / stopping electrode feed
The resistace to electrical current flow increases with it. Causing the electrode to heat

3. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
The Arc voltage
Minimum distortion due to low heat input
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Gives arc voltage values to the control system of the feeder

4. What 2 organizations designate specifications for GMAW wires?
AWS and CSA
If you dont know this check your phone
Constant voltage (CV)
Controls the rate of flow of a shielding gas to the gun nozzle

5. What is the purpose of a regulator and what does it indicate on its gauges?
These terms are quite restrictive and often technically incorrect
3
Reducing the gas source pressure to a constant working pressure
Gas metal arc welding

6. List the factors that determine the mode of metal transfer
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
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
15 feet (4.5 meters)

7. Draw a typical volt amp curve for a machine that is designed for GMAW
Pressure vessels and the piping industry
Reducing the gas source pressure to a constant working pressure
If you dont know this check your phone
5.8 to 12.5 L/min

8. Why is a line heater required when using GMAW?
Short- circuiting transfer - Globular transfer - Spray transfer
3
Dry ice can form within the flow control openings and cause blockage of shielding gas
Penetration and burn - off rate of the electrode

9. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
(DCEP) Direct Current Electrode Positive or Reverse polarity
Cause flaking - which can clog the liner and contact tube
By there current carrying capacity

10. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
To prevent drawing of liquid CO2 (Carbon Dioxide)
Cause flaking - which can clog the liner and contact tube
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

11. A pull type drive system is usually used on what type of material?
85%
To prevent drawing of liquid CO2 (Carbon Dioxide)
Aluminum wire
National Electrical Manufactures Association

12. What controls the wire speed on a voltage sensing wire feeder?
Higher 26 to 35 arc volts
Pressure vessels and the piping industry
The Arc voltage
If you dont know this check your phone

13. What processes are constant current (CC) power sources designed to be used with?
Pressure vessels and the piping industry
SMAW - GTAW
Cause flaking - which can clog the liner and contact tube
Guns

14. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
1/4 inch to 1/2 inch
To limit the short circuiting current so that spatter is reduced
Dry ice can form within the flow control openings and cause blockage of shielding gas

15. 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
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Short- circuiting transfer - Globular transfer - Spray transfer
3

16. What 2 controls are found on a GMAW set- up?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
85%
Gives arc voltage values to the control system of the feeder
Wire feed speed - Voltage control

17. 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
Short- circuiting transfer - Globular transfer - Spray transfer
To prevent leakage - Carbon Dioxide (CO2)
Flux cored wires

18. List 3 forms compressed gases may be supplied for welding
12 to 22 arc volts
These terms are quite restrictive and often technically incorrect
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
The negative side of a welding unit

19. What does a flowmeter do and what does it measure?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
To prevent leakage - Carbon Dioxide (CO2)
Controls the rate of flow of a shielding gas to the gun nozzle
When the filler wire is in direct contract with the base metal

20. Why is globular transfer generally avoided with GMAW?
Controls the rate of flow of a shielding gas to the gun nozzle
Spatter problems and poor weld appearance
(DCEP) Direct Current Electrode Positive or Reverse polarity
Pressure vessels and the piping industry

21. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
85%
Generally not as accurate
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22. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
When the filler wire is in direct contract with the base metal
...
AWS and CSA
Welding process that joins metals by heating them with an electric arc

23. What does the term GMAW identify?
Welding process that joins metals by heating them with an electric arc
20 to 200 times per second
Gas metal arc welding
To prevent drawing of liquid CO2 (Carbon Dioxide)

24. How many times per second does short circuiting take place?
V groove or U groove
Pressure - The rate of flow of a shielding gas
20 to 200 times per second
When the filler wire is in direct contract with the base metal

25. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
Voltage is the force that overcomes resistance to allow amperage flow
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Pressure vessels and the piping industry

26. When is the metal transferred with short circuit transfer?
Higher 26 to 35 arc volts
Speed of the feed motor and - starting / stopping electrode feed
Voltage is the force that overcomes resistance to allow amperage flow
When the filler wire is in direct contract with the base metal

27. What is the key advantage of short circuiting transfer?
Welding process that joins metals by heating them with an electric arc
Minimum distortion due to low heat input
Generally not as accurate
Pressure vessels and the piping industry

28. With straight polarity where is 2/3 of the arc energy?
20 to 200 times per second
The negative side of a welding unit
Generally not as accurate
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

29. What type of power source is used with a constant speed wire feeder?
Constant- speed wire feeders and Voltage- sennsing wire feeders
National Electrical Manufactures Association
Constant voltage (CV)
SMAW - GTAW

30. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
Duty cycle
Gives arc voltage values to the control system of the feeder
DCEP (Direct Current Electrode Positive) Reverse Polarity

31. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
85%
Puddle fluidity
When the filler wire is in direct contract with the base metal

32. What is an advantage of pulsed arc transfer with GMAW?
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
Gives arc voltage values to the control system of the feeder
If you dont know this check your phone

33. In the GMAW process what does amperage control?
Cause flaking - which can clog the liner and contact tube
The Arc voltage
Penetration and burn - off rate of the electrode
V groove or U groove

34. Why must CO2 cylinders be used in the vertical position?
Constant voltage (CV)
National Electrical Manufactures Association
To prevent drawing of liquid CO2 (Carbon Dioxide)
12 to 22 arc volts

35. What is the maximum distance that hard wire can be successfully pushed?
Reducing the gas source pressure to a constant working pressure
15 feet (4.5 meters)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Minimum distortion due to low heat input

36. Why is a fiber washer required and what cylinder gas requires it?
Constant- speed wire feeders and Voltage- sennsing wire feeders
To limit the short circuiting current so that spatter is reduced
To prevent leakage - Carbon Dioxide (CO2)
Motor driven generators - Transformer rectifiers - and Inverter designs

37. What is the recommended electrode stick- out for .035 solid wire?
5.8 to 12.5 L/min
Minimum distortion due to low heat input
1/4 inch to 1/2 inch
85%

38. What would be an indication that the drive roll pressure is adjusted correctly?
Pressure vessels and the piping industry
Wire feeds smoothly (yet will slip should a problem occur in 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
Flux cored wires

39. Regulators control_____________ flowmeters SHOW____________.
Pressure - The rate of flow of a shielding gas
Speed of the feed motor and - starting / stopping electrode feed
...
AWS and CSA

40. In the GMAW process what does voltage control?
Puddle fluidity
National Electrical Manufactures Association
Constant current (CC)
Shielding the molten weld metal from atmospheric contamination

41. What wire are knurled drive rolls most commonly used on?
Flux cored wires
Controls the rate of flow of a shielding gas to the gun nozzle
Constant- speed wire feeders and Voltage- sennsing wire feeders
Insufficient current to melt the wire off cleanly

42. What is another term for electrode holders for GMAW?
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
Motor driven generators - Transformer rectifiers - and Inverter designs
Guns
Insufficient current to melt the wire off cleanly

43. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
The time rate of response for the current rise and fall
If you dont know this check your phone
Constant current (CC)
Wire feeds smoothly (yet will slip should a problem occur in the gun)

44. What output on the welding machine is used to rate the duty cycle?
12 to 22 arc volts
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Minutes of elapsed time continually run (out of 10 minutes)
Penetration and burn - off rate of the electrode

45. What current and polarity is generally used with GMAW?
The resistace to electrical current flow increases with it. Causing the electrode to heat
DCEP (Direct Current Electrode Positive) Reverse Polarity
The Arc voltage
Shielding the molten weld metal from atmospheric contamination

46. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Flux cored wires
Duty cycle
Welding process that joins metals by heating them with an electric arc
Generally not as accurate

47. What does the wire feeder control?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Generally not as accurate
To prevent drawing of liquid CO2 (Carbon Dioxide)
Speed of the feed motor and - starting / stopping electrode feed

48. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Pressure - The rate of flow of a shielding gas
Wire feeds smoothly (yet will slip should a problem occur in the gun)
(DCEP) Direct Current Electrode Positive or Reverse polarity
National Electrical Manufactures Association

49. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
If you dont know this check your phone
Gives arc voltage values to the control system of the feeder
When the filler wire is in direct contract with the base metal

50. List several industries that would use GMAW
The time rate of response for the current rise and fall
20 to 200 times per second
Pressure vessels and the piping industry
To limit the short circuiting current so that spatter is reduced