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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. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Wire feed speed
Voltage is the force that overcomes resistance to allow amperage flow
Higher 26 to 35 arc volts
AWS and CSA

2. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Minimum distortion due to low heat input
Cause flaking - which can clog the liner and contact tube
Generally not as accurate
...

3. What does the wire feeder control?
Spatter problems and poor weld appearance
Speed of the feed motor and - starting / stopping electrode feed
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When the filler wire is in direct contract with the base metal

4. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
Constant voltage (CV)
Constant- speed wire feeders and Voltage- sennsing wire feeders
To limit the short circuiting current so that spatter is reduced

5. What does the term GMAW identify?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Gas metal arc welding
Guns
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

6. What is the effect of too much slope?
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Pressure vessels and the piping industry
Insufficient current to melt the wire off cleanly
V groove or U groove

7. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
Aluminum wire
Flux cored wires
1/4 inch to 1/2 inch

8. What is an advantage of pulsed arc transfer with GMAW?
Wire feed speed
Welding process that joins metals by heating them with an electric arc
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

9. List several industries that would use GMAW
By there current carrying capacity
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Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Pressure vessels and the piping industry

10. What effect does increasing and decreasing the inductance have on the weld?
SMAW - GTAW
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
1/4 inch to 1/2 inch

11. What 2 controls are found on a GMAW set- up?
Wire feed speed - Voltage control
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To prevent leakage - Carbon Dioxide (CO2)
Shielding the molten weld metal from atmospheric contamination

12. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
1/4 inch to 1/2 inch
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

13. What is another term for electrode holders for GMAW?
Spatter problems and poor weld appearance
Gives arc voltage values to the control system of the feeder
Guns
Generally not as accurate

14. What is the purpose of a regulator and what does it indicate on its gauges?
Reducing the gas source pressure to a constant working pressure
These terms are quite restrictive and often technically incorrect
Penetration and burn - off rate of the electrode
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15. What is the recommended electrode stick- out for .035 solid wire?
DCEP (Direct Current Electrode Positive) Reverse Polarity
To limit the short circuiting current so that spatter is reduced
1/4 inch to 1/2 inch
12 to 22 arc volts

16. What type of power source is used with a constant speed wire feeder?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Pressure - The rate of flow of a shielding gas
Constant voltage (CV)
Flux cored wires

17. What controls amperage when using GMAW?
Wire feed speed - Voltage control
These terms are quite restrictive and often technically incorrect
Wire feed speed
Cause flaking - which can clog the liner and contact tube

18. Give a description of 'pinch effect'
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
5.8 to 12.5 L/min
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Voltage is the force that overcomes resistance to allow amperage flow

19. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
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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
3
DCEP (Direct Current Electrode Positive) Reverse Polarity

20. Regulators control_____________ flowmeters SHOW____________.
V groove or U groove
Pressure - The rate of flow of a shielding gas
Shielding the molten weld metal from atmospheric contamination
Puddle fluidity

21. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
20 to 200 times per second
Wire feed speed - Voltage control
V groove or U groove

22. When is the metal transferred with short circuit transfer?
Speed of the feed motor and - starting / stopping electrode feed
When the filler wire is in direct contract with the base metal
National Electrical Manufactures Association
Insufficient current to melt the wire off cleanly

23. Why is a fiber washer required and what cylinder gas requires it?
Pressure - The rate of flow of a shielding gas
85%
Short- circuiting transfer - Globular transfer - Spray transfer
To prevent leakage - Carbon Dioxide (CO2)

24. What does the abbreviation NEMA stand for?
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 feed speed
When the filler wire is in direct contract with the base metal
National Electrical Manufactures Association

25. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
These terms are quite restrictive and often technically incorrect
...
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
(DCEP) Direct Current Electrode Positive or Reverse polarity

26. What wire are knurled drive rolls most commonly used on?
Flux cored wires
1/4 inch to 1/2 inch
The negative side of a welding unit
Penetration and burn - off rate of the electrode

27. What is the preferred drive roll design for solid wires?
Short- circuiting transfer - Globular transfer - Spray transfer
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
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

28. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
The negative side of a welding unit
Gives arc voltage values to the control system of the feeder
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
12 to 22 arc volts

29. Draw a typical volt amp curve for a machine that is designed for GMAW
These terms are quite restrictive and often technically incorrect
If you dont know this check your phone
Gives arc voltage values to the control system of the feeder
20 to 200 times per second

30. In the GMAW process what does amperage control?
The time rate of response for the current rise and fall
Controls the rate of flow of a shielding gas to the gun nozzle
Penetration and burn - off rate of the electrode
3

31. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Gas metal arc welding
Duty cycle
Pressure - The rate of flow of a shielding gas
85%

32. What is the maximum distance that hard wire can be successfully pushed?
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1/4 inch to 1/2 inch
15 feet (4.5 meters)
Minimum distortion due to low heat input

33. List the basic equipment requirements for 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
Duty cycle
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Speed of the feed motor and - starting / stopping electrode feed

34. In the GMAW process what does voltage control?
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
Puddle fluidity

35. What is the main purpose of 'slope'?
The Arc voltage
Pressure vessels and the piping industry
To limit the short circuiting current so that spatter is reduced
Cause flaking - which can clog the liner and contact tube

36. Give a brief description of the GMAW process
Gives arc voltage values to the control system of the feeder
Flux cored wires
Minimum distortion due to low heat input
Welding process that joins metals by heating them with an electric arc

37. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
12 to 22 arc volts
Constant voltage (CV)
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38. What is a typical flow rate of CO2 for short circuit transfer?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
5.8 to 12.5 L/min
The resistace to electrical current flow increases with it. Causing the electrode to heat
DCEP (Direct Current Electrode Positive) Reverse Polarity

39. 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
(DCEP) Direct Current Electrode Positive or Reverse polarity
By there current carrying capacity
Higher 26 to 35 arc volts

40. What is the required arc voltage used for short circuit transfer?
Wire feed speed
12 to 22 arc volts
Controls the rate of flow of a shielding gas to the gun nozzle
1/4 inch to 1/2 inch

41. Why must CO2 cylinders be used in the vertical position?
Spatter problems and poor weld appearance
To prevent drawing of liquid CO2 (Carbon Dioxide)
Pressure vessels and the piping industry
To prevent leakage - Carbon Dioxide (CO2)

42. What current and polarity is generally used with GMAW?
Shielding the molten weld metal from atmospheric contamination
3
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
DCEP (Direct Current Electrode Positive) Reverse Polarity

43. What does inductance control?
Minutes of elapsed time continually run (out of 10 minutes)
AWS and CSA
The time rate of response for the current rise and fall
V groove or U groove

44. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Constant voltage (CV)
These terms are quite restrictive and often technically incorrect
The negative side of a welding unit
85%

45. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Insufficient current to melt the wire off cleanly
(DCEP) Direct Current Electrode Positive or Reverse polarity
Shielding the molten weld metal from atmospheric contamination

46. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Cause flaking - which can clog the liner and contact tube
V groove or U groove
Flux cored wires

47. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
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...
Flux cored wires
Spatter problems and poor weld appearance

48. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Cause flaking - which can clog the liner and contact tube
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Flux cored wires

49. What does a flowmeter do and what does it measure?
Pressure vessels and the piping industry
Welding process that joins metals by heating them with an electric arc
Controls the rate of flow of a shielding gas to the gun nozzle
To limit the short circuiting current so that spatter is reduced

50. What does voltage do in an electrical circuit?
By there current carrying capacity
Controls the rate of flow of a shielding gas to the gun nozzle
Voltage is the force that overcomes resistance to allow amperage flow
To prevent leakage - Carbon Dioxide (CO2)