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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. List the factors that determine the mode of metal transfer
By there current carrying capacity
Shielding the molten weld metal from atmospheric contamination
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
The negative side of a welding unit

2. List several industries that would use GMAW
(DCEP) Direct Current Electrode Positive or Reverse polarity
When the filler wire is in direct contract with the base metal
Pressure vessels and the piping industry
Constant- speed wire feeders and Voltage- sennsing wire feeders

3. How many times per second does short circuiting take place?
1/4 inch to 1/2 inch
20 to 200 times per second
Minimum distortion due to low heat input
V groove or U groove

4. What does a flowmeter do and what does it measure?
Controls the rate of flow of a shielding gas to the gun nozzle
12 to 22 arc volts
These terms are quite restrictive and often technically incorrect
AWS and CSA

5. A pull type drive system is usually used on what type of material?
Aluminum wire
By there current carrying capacity
To limit the short circuiting current so that spatter is reduced
Welding process that joins metals by heating them with an electric arc

6. 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
SMAW - GTAW
Minimum distortion due to low heat input
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7. In the GMAW process what does voltage control?
Reducing the gas source pressure to a constant working pressure
Puddle fluidity
National Electrical Manufactures Association
Minimum distortion due to low heat input

8. What controls amperage when using GMAW?
Wire feed speed
Minimum distortion due to low heat input
Aluminum wire
Insufficient current to melt the wire off cleanly

9. What does the wire feeder control?
Cause flaking - which can clog the liner and contact tube
Speed of the feed motor and - starting / stopping electrode feed
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
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10. Why is the term GMAW preferred over MIG or MAG?
The negative side of a welding unit
These terms are quite restrictive and often technically incorrect
Flux cored wires
Constant current (CC)

11. In the GMAW process what does amperage control?
Gas metal arc welding
Constant voltage (CV)
Penetration and burn - off rate of the electrode
To limit the short circuiting current so that spatter is reduced

12. 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
To prevent leakage - Carbon Dioxide (CO2)
Constant- speed wire feeders and Voltage- sennsing wire feeders
To limit the short circuiting current so that spatter is reduced

13. What is the preferred drive roll design for solid wires?
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3
V groove or U groove
Welding process that joins metals by heating them with an electric arc

14. What 2 organizations designate specifications for GMAW wires?
AWS and CSA
Puddle fluidity
Constant voltage (CV)
By there current carrying capacity

15. What is an advantage of pulsed arc transfer with GMAW?
Gives arc voltage values to the control system of the feeder
Pressure vessels and the piping industry
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

16. What does the abbreviation NEMA stand for?
Flux cored wires
The Arc voltage
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
National Electrical Manufactures Association

17. List 3 wire drive systems and give a short description of each
Controls the rate of flow of a shielding gas to the gun nozzle
Wire feeds smoothly (yet will slip should a problem occur in the gun)
20 to 200 times per second
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

18. What 2 controls are found on a GMAW set- up?
1/4 inch to 1/2 inch
Guns
By there current carrying capacity
Wire feed speed - Voltage control

19. Why is a line heater required when using GMAW?
To limit the short circuiting current so that spatter is reduced
15 feet (4.5 meters)
Dry ice can form within the flow control openings and cause blockage of shielding gas
Insufficient current to melt the wire off cleanly

20. What is a solenoid valve and what actuates it?
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
Controls the rate of flow of a shielding gas to the gun nozzle
Wire feed speed - Voltage control
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

21. Why is a fiber washer required and what cylinder gas requires it?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
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
Flux cored wires

22. Why is globular transfer generally avoided with GMAW?
Constant voltage (CV)
Spatter problems and poor weld appearance
Welding process that joins metals by heating them with an electric arc
Constant current (CC)

23. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
The negative side of a welding unit
The resistace to electrical current flow increases with it. Causing the electrode to heat
Speed of the feed motor and - starting / stopping electrode feed

24. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Welding process that joins metals by heating them with an electric arc
(DCEP) Direct Current Electrode Positive or Reverse polarity
Pressure - The rate of flow of a shielding gas
AWS and CSA

25. What does voltage do in an electrical circuit?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Voltage is the force that overcomes resistance to allow amperage flow
Flux cored wires
Insufficient current to melt the wire off cleanly

26. What is the purpose of the shielding gas used in GMAW?
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
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

27. What current and polarity is generally used with GMAW?
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DCEP (Direct Current Electrode Positive) Reverse Polarity
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Generally not as accurate

28. 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)
Generally not as accurate
To prevent leakage - Carbon Dioxide (CO2)
20 to 200 times per second

29. When is the metal transferred with short circuit transfer?
3
12 to 22 arc volts
When the filler wire is in direct contract with the base metal
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

30. What is the effect of too much slope?
To prevent leakage - Carbon Dioxide (CO2)
The resistace to electrical current flow increases with it. Causing the electrode to heat
Short- circuiting transfer - Globular transfer - Spray transfer
Insufficient current to melt the wire off cleanly

31. List 3 forms compressed gases may be supplied for welding
Spatter problems and poor weld appearance
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
By there current carrying capacity
Constant current (CC)

32. Draw a typical volt amp curve for a machine that is designed for GMAW
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
85%
To prevent leakage - Carbon Dioxide (CO2)

33. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Insufficient current to melt the wire off cleanly
Cause flaking - which can clog the liner and contact tube
Minutes of elapsed time continually run (out of 10 minutes)
Flux cored wires

34. What is another term for electrode holders for GMAW?
Guns
Duty cycle
When the filler wire is in direct contract with the base metal
Shielding the molten weld metal from atmospheric contamination

35. What is the purpose of a regulator and what does it indicate on its gauges?
By there current carrying capacity
Reducing the gas source pressure to a constant working pressure
12 to 22 arc volts
Constant- speed wire feeders and Voltage- sennsing wire feeders

36. How are GMAW guns rated?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
When the filler wire is in direct contract with the base metal
Higher 26 to 35 arc volts
By there current carrying capacity

37. Give a brief description of the GMAW process
If you dont know this check your phone
To prevent drawing of liquid CO2 (Carbon Dioxide)
Welding process that joins metals by heating them with an electric arc
Minutes of elapsed time continually run (out of 10 minutes)

38. What is the maximum distance that hard wire can be successfully pushed?
National Electrical Manufactures Association
To prevent drawing of liquid CO2 (Carbon Dioxide)
15 feet (4.5 meters)
When the filler wire is in direct contract with the base metal

39. What type of power source is commonly used with a voltage sensing wire feeder?
V groove or U groove
Constant current (CC)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Wire feeds smoothly (yet will slip should a problem occur in the gun)

40. What does inductance control?
The time rate of response for the current rise and fall
Gives arc voltage values to the control system of the feeder
15 feet (4.5 meters)
1/4 inch to 1/2 inch

41. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
15 feet (4.5 meters)
(DCEP) Direct Current Electrode Positive or Reverse polarity

42. List the three methods of metal transfer with GMAW
Speed of the feed motor and - starting / stopping electrode feed
Minimum distortion due to low heat input
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Short- circuiting transfer - Globular transfer - Spray transfer

43. What effect does increasing and decreasing the inductance have on the weld?
Flux cored wires
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
If you dont know this check your phone
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

44. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
The negative side of a welding unit
Pressure vessels and the piping industry
V groove or U groove

45. What does the term GMAW identify?
Gas metal arc welding
Minimum distortion due to low heat input
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Constant voltage (CV)

46. What is the key advantage of short circuiting transfer?
AWS and CSA
Minimum distortion due to low heat input
Wire feeds smoothly (yet will slip should a problem occur in the gun)
The negative side of a welding unit

47. What controls the wire speed on a voltage sensing wire feeder?
Short- circuiting transfer - Globular transfer - Spray transfer
The Arc voltage
Controls the rate of flow of a shielding gas to the gun nozzle
3

48. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
12 to 22 arc volts
Gives arc voltage values to the control system of the feeder
V groove or U groove
Short- circuiting transfer - Globular transfer - Spray transfer

49. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
Shielding the molten weld metal from atmospheric contamination
If you dont know this check your phone
To limit the short circuiting current so that spatter is reduced

50. What is the recommended electrode stick- out for .035 solid wire?
15 feet (4.5 meters)
Shielding the molten weld metal from atmospheric contamination
Minutes of elapsed time continually run (out of 10 minutes)
1/4 inch to 1/2 inch