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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 disadvantage of the gauge preset type of regulator/flowmeter?
By there current carrying capacity
SMAW - GTAW
Insufficient current to melt the wire off cleanly
Generally not as accurate

2. What is the preferred drive roll design for solid wires?
National Electrical Manufactures Association
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
V groove or U groove
Puddle fluidity

3. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
1/4 inch to 1/2 inch
Flux cored wires
The resistace to electrical current flow increases with it. Causing the electrode to heat

4. Give a brief description of the GMAW process
SMAW - GTAW
Cause flaking - which can clog the liner and contact tube
Welding process that joins metals by heating them with an electric arc
Generally not as accurate

5. What controls amperage when using GMAW?
When the filler wire is in direct contract with the base metal
To prevent drawing of liquid CO2 (Carbon Dioxide)
These terms are quite restrictive and often technically incorrect
Wire feed speed

6. What type of power source is commonly used with a voltage sensing wire feeder?
(DCEP) Direct Current Electrode Positive or Reverse polarity
To prevent leakage - Carbon Dioxide (CO2)
Constant current (CC)
Spatter problems and poor weld appearance

7. What is the maximum distance that hard wire can be successfully pushed?
15 feet (4.5 meters)
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To limit the short circuiting current so that spatter is reduced
When the filler wire is in direct contract with the base metal

8. How are GMAW guns rated?
By there current carrying capacity
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
3
Higher 26 to 35 arc volts

9. Why is a fiber washer required and what cylinder gas requires it?
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
The Arc voltage
To prevent leakage - Carbon Dioxide (CO2)

10. 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
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
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 the pick- up lead on a voltage sensing wire feeder?
Gives arc voltage values to the control system of the feeder
Controls the rate of flow of a shielding gas to the gun nozzle
Short- circuiting transfer - Globular transfer - Spray transfer
Spatter problems and poor weld appearance

12. What wire are knurled drive rolls most commonly used on?
Wire feed speed
Gas metal arc welding
Flux cored wires
Pressure vessels and the piping industry

13. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
To prevent leakage - Carbon Dioxide (CO2)
Spatter problems and poor weld appearance
Constant voltage (CV)

14. What current and polarity is generally used with GMAW?
12 to 22 arc volts
Wire feed speed - Voltage control
V groove or U groove
DCEP (Direct Current Electrode Positive) Reverse Polarity

15. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Cause flaking - which can clog the liner and contact tube
Constant- speed wire feeders and Voltage- sennsing wire feeders
...
Duty cycle

16. Why must CO2 cylinders be used in the vertical position?
Wire feed speed
DCEP (Direct Current Electrode Positive) Reverse Polarity
To prevent drawing of liquid CO2 (Carbon Dioxide)
Guns

17. Why is globular transfer generally avoided with GMAW?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Spatter problems and poor weld appearance
The Arc voltage
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18. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
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 prevent drawing of liquid CO2 (Carbon Dioxide)
Cause flaking - which can clog the liner and contact tube

19. A pull type drive system is usually used on what type of material?
Aluminum wire
Minimum distortion due to low heat input
Insufficient current to melt the wire off cleanly
These terms are quite restrictive and often technically incorrect

20. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Flux cored wires
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Constant voltage (CV)

21. What is an advantage of pulsed arc transfer with GMAW?
Duty cycle
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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1/4 inch to 1/2 inch

22. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
DCEP (Direct Current Electrode Positive) Reverse Polarity
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Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
The resistace to electrical current flow increases with it. Causing the electrode to heat

23. Why is the term GMAW preferred over MIG or MAG?
Spatter problems and poor weld appearance
12 to 22 arc volts
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
These terms are quite restrictive and often technically incorrect

24. What effect does increasing and decreasing the inductance have on the weld?
The resistace to electrical current flow increases with it. Causing the electrode to heat
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Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
...

25. What processes are constant current (CC) power sources designed to be used with?
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Voltage is the force that overcomes resistance to allow amperage flow
V groove or U groove
SMAW - GTAW

26. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Motor driven generators - Transformer rectifiers - and Inverter designs
Higher 26 to 35 arc volts
Wire feed speed

27. In the GMAW process what does voltage control?
DCEP (Direct Current Electrode Positive) Reverse Polarity
To prevent drawing of liquid CO2 (Carbon Dioxide)
Puddle fluidity
Wire feeds smoothly (yet will slip should a problem occur in the gun)

28. What does inductance control?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
The time rate of response for the current rise and fall
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

29. List 3 wire drive systems and give a short description of each
Aluminum wire
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
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
SMAW - GTAW

30. What does the abbreviation NEMA stand for?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
The resistace to electrical current flow increases with it. Causing the electrode to heat
National Electrical Manufactures Association
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

31. How many times per second does short circuiting take place?
Aluminum wire
Shielding the molten weld metal from atmospheric contamination
20 to 200 times per second
Penetration and burn - off rate of the electrode

32. List the three methods of metal transfer with GMAW
Minimum distortion due to low heat input
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
Short- circuiting transfer - Globular transfer - Spray transfer

33. Draw a typical volt amp curve for a machine that is designed for GMAW
Speed of the feed motor and - starting / stopping electrode feed
The resistace to electrical current flow increases with it. Causing the electrode to heat
Aluminum wire
If you dont know this check your phone

34. What is the purpose of the shielding gas used in 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
Dry ice can form within the flow control openings and cause blockage of shielding gas
By there current carrying capacity
Shielding the molten weld metal from atmospheric contamination

35. What does the term GMAW identify?
85%
Gas metal arc welding
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

36. What 2 controls are found on a GMAW set- up?
Wire feed speed - Voltage control
...
Wire feeds smoothly (yet will slip should a problem occur in the gun)
To limit the short circuiting current so that spatter is reduced

37. What is the key advantage of short circuiting transfer?
Short- circuiting transfer - Globular transfer - Spray transfer
Insufficient current to melt the wire off cleanly
Minimum distortion due to low heat input
When the filler wire is in direct contract with the base metal

38. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
DCEP (Direct Current Electrode Positive) Reverse Polarity
(DCEP) Direct Current Electrode Positive or Reverse polarity
20 to 200 times per second

39. List several industries that would use GMAW
Wire feeds smoothly (yet will slip should a problem occur in the gun)
5.8 to 12.5 L/min
1/4 inch to 1/2 inch
Pressure vessels and the piping industry

40. What is the effect of too much slope?
Wire feed speed - Voltage control
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
If you dont know this check your phone
Insufficient current to melt the wire off cleanly

41. What type of power source is used with a constant speed wire feeder?
AWS and CSA
Pressure - The rate of flow of a shielding gas
To limit the short circuiting current so that spatter is reduced
Constant voltage (CV)

42. Regulators control_____________ flowmeters SHOW____________.
Pressure - The rate of flow of a shielding gas
Shielding the molten weld metal from atmospheric contamination
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Higher 26 to 35 arc volts

43. What is the required arc voltage used for short circuit transfer?
12 to 22 arc volts
Constant- speed wire feeders and Voltage- sennsing wire feeders
These terms are quite restrictive and often technically incorrect
Puddle fluidity

44. Why is a line heater required when using GMAW?
15 feet (4.5 meters)
The time rate of response for the current rise and fall
...
Dry ice can form within the flow control openings and cause blockage of shielding gas

45. List the factors that determine the mode of metal transfer
Insufficient current to melt the wire off cleanly
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
(DCEP) Direct Current Electrode Positive or Reverse polarity
If you dont know this check your phone

46. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
Speed of the feed motor and - starting / stopping electrode feed
The time rate of response for the current rise and fall
V groove or U groove

47. 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)
These terms are quite restrictive and often technically incorrect
Wire feed speed
V groove or U groove

48. List 3 forms compressed gases may be supplied for welding
Controls the rate of flow of a shielding gas to the gun nozzle
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Dry ice can form within the flow control openings and cause blockage of shielding gas

49. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
3
Constant current (CC)

50. What is the recommended electrode stick- out for .035 solid wire?
Minutes of elapsed time continually run (out of 10 minutes)
When the filler wire is in direct contract with the base metal
1/4 inch to 1/2 inch
Dry ice can form within the flow control openings and cause blockage of shielding gas