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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 purpose of the shielding gas used in GMAW?
12 to 22 arc volts
Controls the rate of flow of a shielding gas to the gun nozzle
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Shielding the molten weld metal from atmospheric contamination

2. When is the metal transferred with short circuit transfer?
Guns
Generally not as accurate
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
When the filler wire is in direct contract with the base metal

3. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
To limit the short circuiting current so that spatter is reduced
Voltage is the force that overcomes resistance to allow amperage flow
...
20 to 200 times per second

4. What is another term for electrode holders for GMAW?
Gas metal arc welding
Guns
Constant current (CC)
V groove or U groove

5. What is the main purpose of 'slope'?
National Electrical Manufactures Association
To limit the short circuiting current so that spatter is reduced
To prevent leakage - Carbon Dioxide (CO2)
Welding process that joins metals by heating them with an electric arc

6. List 3 forms compressed gases may be supplied for welding
Constant- speed wire feeders and Voltage- sennsing wire feeders
Dry ice can form within the flow control openings and cause blockage of shielding gas
Spatter problems and poor weld appearance
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

7. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
20 to 200 times per second
Pressure - The rate of flow of a shielding gas
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

8. Why is a line heater required when using GMAW?
3
Voltage is the force that overcomes resistance to allow amperage flow
12 to 22 arc volts
Dry ice can form within the flow control openings and cause blockage of shielding gas

9. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
85%
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5.8 to 12.5 L/min

10. What is the preferred drive roll design for solid wires?
5.8 to 12.5 L/min
Controls the rate of flow of a shielding gas to the gun nozzle
Spatter problems and poor weld appearance
V groove or U groove

11. What type of power source is commonly used with a voltage sensing wire feeder?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Constant voltage (CV)
Reducing the gas source pressure to a constant working pressure
Constant current (CC)

12. List 3 wire drive systems and give a short description of each
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
3
The Arc voltage
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

13. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
Penetration and burn - off rate of the electrode
Dry ice can form within the flow control openings and cause blockage of shielding gas
85%

14. What effect does increasing and decreasing the inductance have on the weld?
85%
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

15. What is the maximum distance that hard wire can be successfully pushed?
15 feet (4.5 meters)
...
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
85%

16. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Minutes of elapsed time continually run (out of 10 minutes)
Duty cycle
These terms are quite restrictive and often technically incorrect
Controls the rate of flow of a shielding gas to the gun nozzle

17. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
The time rate of response for the current rise and fall
When the filler wire is in direct contract with the base metal
Wire feed speed - Voltage control

18. What is the recommended electrode stick- out for .035 solid wire?
Guns
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Constant voltage (CV)
1/4 inch to 1/2 inch

19. What current and polarity is generally used with GMAW?
To prevent drawing of liquid CO2 (Carbon Dioxide)
DCEP (Direct Current Electrode Positive) Reverse Polarity
Cause flaking - which can clog the liner and contact tube
When the filler wire is in direct contract with the base metal

20. What does the wire feeder control?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Reducing the gas source pressure to a constant working pressure
85%
Speed of the feed motor and - starting / stopping electrode feed

21. List several industries that would use GMAW
Pressure vessels and the piping industry
The resistace to electrical current flow increases with it. Causing the electrode to heat
SMAW - GTAW
1/4 inch to 1/2 inch

22. What 2 organizations designate specifications for GMAW wires?
By there current carrying capacity
AWS and CSA
Spatter problems and poor weld appearance
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23. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
3
Cause flaking - which can clog the liner and contact tube
Gives arc voltage values to the control system of the feeder
Welding process that joins metals by heating them with an electric arc

24. In the GMAW process what does voltage control?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
V groove or U groove
Duty cycle
Puddle fluidity

25. What are the 2 types of wire feeders available?
Gives arc voltage values to the control system of the feeder
Minimum distortion due to low heat input
Constant- speed wire feeders and Voltage- sennsing wire feeders
5.8 to 12.5 L/min

26. 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)
Wire feed speed - Voltage control
Insufficient current to melt the wire off cleanly
National Electrical Manufactures Association

27. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
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
Spatter problems and poor weld appearance
If you dont know this check your phone

28. What does a flowmeter do and what does it measure?
If you dont know this check your phone
Minimum distortion due to low heat input
3
Controls the rate of flow of a shielding gas to the gun nozzle

29. In the GMAW process what does amperage control?
Flux cored wires
Penetration and burn - off rate of the electrode
Motor driven generators - Transformer rectifiers - and Inverter designs
12 to 22 arc volts

30. What wire are knurled drive rolls most commonly used on?
Welding process that joins metals by heating them with an electric arc
Guns
15 feet (4.5 meters)
Flux cored wires

31. Regulators control_____________ flowmeters SHOW____________.
Pressure - The rate of flow of a shielding gas
Reducing the gas source pressure to a constant working pressure
By there current carrying capacity
Wire feeds smoothly (yet will slip should a problem occur in the gun)

32. What power sources are used with the GMAW Process?
Duty cycle
Gives arc voltage values to the control system of the feeder
1/4 inch to 1/2 inch
Motor driven generators - Transformer rectifiers - and Inverter designs

33. What controls the wire speed on a voltage sensing wire feeder?
National Electrical Manufactures Association
The Arc voltage
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
12 to 22 arc volts

34. What is the purpose of a regulator and what does it indicate on its gauges?
Short- circuiting transfer - Globular transfer - Spray transfer
Duty cycle
Reducing the gas source pressure to a constant working pressure
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

35. A pull type drive system is usually used on what type of material?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Aluminum wire
Cause flaking - which can clog the liner and contact tube
AWS and CSA

36. What output on the welding machine is used to rate the duty cycle?
Pressure - The rate of flow of a shielding gas
Minutes of elapsed time continually run (out of 10 minutes)
85%
Speed of the feed motor and - starting / stopping electrode feed

37. What is the effect of too much slope?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
The time rate of response for the current rise and fall
Insufficient current to melt the wire off cleanly
Gas metal arc welding

38. What is a typical flow rate of CO2 for short circuit transfer?
Gives arc voltage values to the control system of the feeder
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Spatter problems and poor weld appearance
5.8 to 12.5 L/min

39. Why must CO2 cylinders be used in the vertical position?
Minimum distortion due to low heat input
To prevent drawing of liquid CO2 (Carbon Dioxide)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Shielding the molten weld metal from atmospheric contamination

40. What does inductance control?
Generally not as accurate
Reducing the gas source pressure to a constant working pressure
The time rate of response for the current rise and fall
Welding process that joins metals by heating them with an electric arc

41. What does the abbreviation NEMA stand for?
Guns
Generally not as accurate
Flux cored wires
National Electrical Manufactures Association

42. Give a brief description of the GMAW process
Minimum distortion due to low heat input
Duty cycle
To prevent drawing of liquid CO2 (Carbon Dioxide)
Welding process that joins metals by heating them with an electric arc

43. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
V groove or U groove
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
To limit the short circuiting current so that spatter is reduced
Higher 26 to 35 arc volts

44. Why is the term GMAW preferred over MIG or MAG?
Constant current (CC)
(DCEP) Direct Current Electrode Positive or Reverse polarity
These terms are quite restrictive and often technically incorrect
85%

45. List the three methods of metal transfer with GMAW
Wire feeds smoothly (yet will slip should a problem occur in the gun)
These terms are quite restrictive and often technically incorrect
National Electrical Manufactures Association
Short- circuiting transfer - Globular transfer - Spray transfer

46. List the basic equipment requirements for the GMAW process
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Controls the rate of flow of a shielding gas to the gun nozzle
Cause flaking - which can clog the liner and contact tube
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

47. What happens when the electrode extension is increased?
Constant- speed wire feeders and Voltage- sennsing wire feeders
The resistace to electrical current flow increases with it. Causing the electrode to heat
Cause flaking - which can clog the liner and contact tube
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

48. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
Cause flaking - which can clog the liner and contact tube
If you dont know this check your phone
Constant- speed wire feeders and Voltage- sennsing wire feeders

49. With straight polarity where is 2/3 of the arc energy?
The resistace to electrical current flow increases with it. Causing the electrode to heat
15 feet (4.5 meters)
The negative side of a welding unit
Shielding the molten weld metal from atmospheric contamination

50. What is the required arc voltage used for short circuit transfer?
The time rate of response for the current rise and fall
SMAW - GTAW
When the filler wire is in direct contract with the base metal
12 to 22 arc volts