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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 3 forms compressed gases may be supplied for welding
(DCEP) Direct Current Electrode Positive or Reverse polarity
The resistace to electrical current flow increases with it. Causing the electrode to heat
To prevent drawing of liquid CO2 (Carbon Dioxide)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

2. What type of power source is used with a constant speed wire feeder?
Pressure - The rate of flow of a shielding gas
12 to 22 arc volts
Constant voltage (CV)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

3. What does inductance control?
Reducing the gas source pressure to a constant working pressure
Speed of the feed motor and - starting / stopping electrode feed
The time rate of response for the current rise and fall
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

4. In the GMAW process what does voltage control?
Spatter problems and poor weld appearance
Puddle fluidity
15 feet (4.5 meters)
National Electrical Manufactures Association

5. What power sources are used with the GMAW Process?
Constant current (CC)
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
Motor driven generators - Transformer rectifiers - and Inverter designs

6. What does a flowmeter do and what does it measure?
Constant current (CC)
Gas metal arc welding
If you dont know this check your phone
Controls the rate of flow of a shielding gas to the gun nozzle

7. What is an advantage of pulsed arc transfer with GMAW?
Short- circuiting transfer - Globular transfer - Spray transfer
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Minimum distortion due to low heat input
Speed of the feed motor and - starting / stopping electrode feed

8. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
By there current carrying capacity
Minutes of elapsed time continually run (out of 10 minutes)
DCEP (Direct Current Electrode Positive) Reverse Polarity
85%

9. What 2 controls are found on a GMAW set- up?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Wire feed speed - Voltage control
To prevent leakage - Carbon Dioxide (CO2)
To limit the short circuiting current so that spatter is reduced

10. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Wire feed speed - Voltage control
Controls the rate of flow of a shielding gas to the gun nozzle
Higher 26 to 35 arc volts

11. What is a typical flow rate of CO2 for short circuit transfer?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
5.8 to 12.5 L/min
Guns
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

12. What is the preferred drive roll design for solid wires?
V groove or U groove
National Electrical Manufactures Association
Speed of the feed motor and - starting / stopping electrode feed
Flux cored wires

13. What effect does increasing and decreasing the inductance have on the weld?
Minimum distortion due to low heat input
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 process that joins metals by heating them with an electric arc
Insufficient current to melt the wire off cleanly

14. How many times per second does short circuiting take place?
Constant voltage (CV)
The time rate of response for the current rise and fall
Spatter problems and poor weld appearance
20 to 200 times per second

15. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
Aluminum wire
20 to 200 times per second
Constant- speed wire feeders and Voltage- sennsing wire feeders

16. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Pressure vessels and the piping industry
The Arc voltage
3
To limit the short circuiting current so that spatter is reduced

17. What controls the wire speed on a voltage sensing wire feeder?
To limit the short circuiting current so that spatter is reduced
Controls the rate of flow of a shielding gas to the gun nozzle
The Arc voltage
Puddle fluidity

18. Draw a typical volt amp curve for a machine that is designed for GMAW
Insufficient current to melt the wire off cleanly
Cause flaking - which can clog the liner and contact tube
If you dont know this check your phone
Wire feeds smoothly (yet will slip should a problem occur in the gun)

19. Why is a fiber washer required and what cylinder gas requires it?
Pressure vessels and the piping industry
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)
SMAW - GTAW

20. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Flux cored wires
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
V groove or U groove
Gives arc voltage values to the control system of the feeder

21. Why is a line heater required when using GMAW?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Dry ice can form within the flow control openings and cause blockage of shielding gas
If you dont know this check your phone

22. When is the metal transferred with short circuit transfer?
Motor driven generators - Transformer rectifiers - and Inverter designs
When the filler wire is in direct contract with the base metal
Short- circuiting transfer - Globular transfer - Spray transfer
Cause flaking - which can clog the liner and contact tube

23. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Cause flaking - which can clog the liner and contact tube
Minimum distortion due to low heat input
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
15 feet (4.5 meters)

24. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Minutes of elapsed time continually run (out of 10 minutes)
Welding process that joins metals by heating them with an electric arc
Duty cycle

25. What wire are knurled drive rolls most commonly used on?
Cause flaking - which can clog the liner and contact tube
If you dont know this check your phone
Flux cored wires
85%

26. List the three methods of metal transfer with GMAW
Minimum distortion due to low heat input
Constant- speed wire feeders and Voltage- sennsing wire feeders
Short- circuiting transfer - Globular transfer - Spray transfer
If you dont know this check your phone

27. Why must CO2 cylinders be used in the vertical position?
Penetration and burn - off rate of the electrode
To prevent drawing of liquid CO2 (Carbon Dioxide)
Generally not as accurate
Wire feed speed

28. What are the 2 types of wire feeders available?
Wire feed speed - Voltage control
Aluminum wire
Constant- speed wire feeders and Voltage- sennsing wire feeders
To prevent leakage - Carbon Dioxide (CO2)

29. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Gas metal arc welding
V groove or U groove
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Higher 26 to 35 arc volts

30. What is a solenoid valve and what actuates it?
1/4 inch to 1/2 inch
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
To prevent leakage - Carbon Dioxide (CO2)
Minutes of elapsed time continually run (out of 10 minutes)

31. Give a description of 'pinch effect'
Insufficient current to melt the wire off cleanly
Shielding the molten weld metal from atmospheric contamination
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

32. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Generally not as accurate
Flux cored wires

33. Regulators control_____________ flowmeters SHOW____________.
(DCEP) Direct Current Electrode Positive or Reverse polarity
Pressure - The rate of flow of a shielding gas
Penetration and burn - off rate of the electrode
Higher 26 to 35 arc volts

34. What is the required arc voltage used for short circuit transfer?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
By there current carrying capacity
Aluminum wire
12 to 22 arc volts

35. In the GMAW process what does amperage control?
Aluminum wire
Penetration and burn - off rate of the electrode
12 to 22 arc volts
Constant current (CC)

36. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
3
To prevent leakage - Carbon Dioxide (CO2)
If you dont know this check your phone

37. Why is the term GMAW preferred over MIG or MAG?
If you dont know this check your phone
...
Gas metal arc welding
These terms are quite restrictive and often technically incorrect

38. What does the wire feeder control?
Penetration and burn - off rate of the electrode
Speed of the feed motor and - starting / stopping electrode feed
The negative side of a welding unit
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

39. What is the purpose of a regulator and what does it indicate on its gauges?
Constant voltage (CV)
Reducing the gas source pressure to a constant working pressure
The negative side of a welding unit
5.8 to 12.5 L/min

40. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
Duty cycle
SMAW - GTAW
AWS and CSA

41. What is the effect of too much slope?
SMAW - GTAW
Insufficient current to melt the wire off cleanly
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
By there current carrying capacity

42. What type of power source is commonly used with a voltage sensing wire feeder?
Welding process that joins metals by heating them with an electric arc
Constant current (CC)
Gives arc voltage values to the control system of the feeder
National Electrical Manufactures Association

43. What 2 organizations designate specifications for GMAW wires?
Duty cycle
Voltage is the force that overcomes resistance to allow amperage flow
AWS and CSA
Puddle fluidity

44. What is the maximum distance that hard wire can be successfully pushed?
By there current carrying capacity
Penetration and burn - off rate of the electrode
15 feet (4.5 meters)
Guns

45. Give a brief description of the GMAW process
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 process that joins metals by heating them with an electric arc
...
SMAW - GTAW

46. What is the main purpose of 'slope'?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
National Electrical Manufactures Association
To limit the short circuiting current so that spatter is reduced
Wire feed speed

47. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Pressure - The rate of flow of a shielding gas
If you dont know this check your phone
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Spatter problems and poor weld appearance

48. What happens when the electrode extension is increased?
V groove or U groove
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
The resistace to electrical current flow increases with it. Causing the electrode to heat
Spatter problems and poor weld appearance

49. What controls amperage when using GMAW?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Gas metal arc welding
The Arc voltage
Wire feed speed

50. What does the term GMAW identify?
Gas metal arc welding
15 feet (4.5 meters)
SMAW - GTAW
Constant voltage (CV)