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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 key advantage of short circuiting transfer?
Minimum distortion due to low heat input
Dry ice can form within the flow control openings and cause blockage of shielding gas
Speed of the feed motor and - starting / stopping electrode feed
Pressure - The rate of flow of a shielding gas

2. What type of power source is used with a constant speed wire feeder?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
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)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

3. What controls the wire speed on a voltage sensing wire feeder?
When the filler wire is in direct contract with the base metal
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Constant current (CC)
The Arc voltage

4. What 2 controls are found on a GMAW set- up?
Wire feed speed - Voltage control
...
85%
5.8 to 12.5 L/min

5. What is a solenoid valve and what actuates it?
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)
Dry ice can form within the flow control openings and cause blockage of shielding gas
Gives arc voltage values to the control system of the feeder

6. Regulators control_____________ flowmeters SHOW____________.
Generally not as accurate
Pressure - The rate of flow of a shielding gas
To limit the short circuiting current so that spatter is reduced
12 to 22 arc volts

7. What is the purpose of the shielding gas used in GMAW?
To limit the short circuiting current so that spatter is reduced
Constant voltage (CV)
Gas metal arc welding
Shielding the molten weld metal from atmospheric contamination

8. How many times per second does short circuiting take place?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
3
20 to 200 times per second
Wire feed speed

9. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Spatter problems and poor weld appearance
Cause flaking - which can clog the liner and contact tube
Duty cycle
...

10. What power sources are used with the GMAW Process?
85%
When the filler wire is in direct contract with the base metal
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
Motor driven generators - Transformer rectifiers - and Inverter designs

11. What is the preferred drive roll design for solid wires?
V groove or U groove
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
Gives arc voltage values to the control system of the feeder

12. Draw a typical volt amp curve for a machine that is designed for GMAW
V groove or U groove
Pressure - The rate of flow of a shielding gas
Cause flaking - which can clog the liner and contact tube
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13. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
Flux cored wires
Duty cycle
Constant voltage (CV)

14. What current and polarity is generally used with GMAW?
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
...
Minimum distortion due to low heat input

15. What type of power source is commonly used with a voltage sensing wire feeder?
Constant current (CC)
The time rate of response for the current rise and fall
SMAW - GTAW
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

16. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Voltage is the force that overcomes resistance to allow amperage flow
85%
20 to 200 times per second
Wire feed speed

17. What does voltage do in an electrical circuit?
Constant current (CC)
Speed of the feed motor and - starting / stopping electrode feed
Minimum distortion due to low heat input
Voltage is the force that overcomes resistance to allow amperage flow

18. What does inductance control?
5.8 to 12.5 L/min
If you dont know this check your phone
The time rate of response for the current rise and fall
To prevent drawing of liquid CO2 (Carbon Dioxide)

19. What effect does increasing and decreasing the inductance have on the weld?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
3
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Short- circuiting transfer - Globular transfer - Spray transfer

20. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Duty cycle
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

21. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
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Penetration and burn - off rate of the electrode
1/4 inch to 1/2 inch
Puddle fluidity

22. Why is the term GMAW preferred over MIG or MAG?
AWS and CSA
Constant voltage (CV)
These terms are quite restrictive and often technically incorrect
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

23. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
DCEP (Direct Current Electrode Positive) Reverse Polarity
Dry ice can form within the flow control openings and cause blockage of shielding gas
If you dont know this check your phone

24. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
The Arc voltage
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Generally not as accurate

25. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Speed of the feed motor and - starting / stopping electrode feed
Aluminum wire
(DCEP) Direct Current Electrode Positive or Reverse polarity
Dry ice can form within the flow control openings and cause blockage of shielding gas

26. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
3
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
The time rate of response for the current rise and fall

27. What does the abbreviation NEMA stand for?
These terms are quite restrictive and often technically incorrect
National Electrical Manufactures Association
Flux cored wires
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

28. What does the wire feeder control?
The Arc voltage
Wire feed speed
Speed of the feed motor and - starting / stopping electrode feed
If you dont know this check your phone

29. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Gives arc voltage values to the control system of the feeder
Voltage is the force that overcomes resistance to allow amperage flow

30. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Constant voltage (CV)
Voltage is the force that overcomes resistance to allow amperage flow
3
The Arc voltage

31. What 2 organizations designate specifications for GMAW wires?
AWS and CSA
The Arc voltage
Higher 26 to 35 arc volts
Shielding the molten weld metal from atmospheric contamination

32. In the GMAW process what does voltage control?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Puddle fluidity
DCEP (Direct Current Electrode Positive) Reverse Polarity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

33. What is the main purpose of 'slope'?
Minimum distortion due to low heat input
The negative side of a welding unit
Higher 26 to 35 arc volts
To limit the short circuiting current so that spatter is reduced

34. What would be an indication that the drive roll pressure is adjusted correctly?
Higher 26 to 35 arc volts
Constant voltage (CV)
SMAW - GTAW
Wire feeds smoothly (yet will slip should a problem occur in the gun)

35. How are GMAW guns rated?
Wire feed speed
The negative side of a welding unit
By there current carrying capacity
20 to 200 times per second

36. What is the disadvantage of the gauge preset type of regulator/flowmeter?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Generally not as accurate
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Constant current (CC)

37. What is the maximum distance that hard wire can be successfully pushed?
15 feet (4.5 meters)
The negative side of a welding unit
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) Reverse Polarity

38. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
Constant- speed wire feeders and Voltage- sennsing wire feeders
DCEP (Direct Current Electrode Positive) Reverse Polarity
Puddle fluidity

39. What is another term for electrode holders for GMAW?
Pressure - The rate of flow of a shielding gas
To limit the short circuiting current so that spatter is reduced
Guns
Constant voltage (CV)

40. List the basic equipment requirements for the GMAW process
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Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
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

41. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
Constant current (CC)
5.8 to 12.5 L/min
When the filler wire is in direct contract with the base metal

42. What is a typical flow rate of CO2 for short circuit transfer?
The Arc voltage
The negative side of a welding unit
Guns
5.8 to 12.5 L/min

43. List the factors that determine the mode of metal transfer
Short- circuiting transfer - Globular transfer - Spray transfer
Controls the rate of flow of a shielding gas to the gun nozzle
Gives arc voltage values to the control system of the feeder
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

44. When is the metal transferred with short circuit transfer?
The time rate of response for the current rise and fall
When the filler wire is in direct contract with the base metal
DCEP (Direct Current Electrode Positive) Reverse Polarity
Wire feed speed - Voltage control

45. A pull type drive system is usually used on what type of material?
Aluminum wire
Dry ice can form within the flow control openings and cause blockage of shielding gas
Wire feed speed
Higher 26 to 35 arc volts

46. What output on the welding machine is used to rate the duty cycle?
SMAW - GTAW
The resistace to electrical current flow increases with it. Causing the electrode to heat
Reducing the gas source pressure to a constant working pressure
Minutes of elapsed time continually run (out of 10 minutes)

47. What is the purpose of a regulator and what does it indicate on its gauges?
Cause flaking - which can clog the liner and contact tube
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Reducing the gas source pressure to a constant working pressure

48. What wire are knurled drive rolls most commonly used on?
Generally not as accurate
Guns
Flux cored wires
Wire feeds smoothly (yet will slip should a problem occur in the gun)

49. What does the term GMAW identify?
Flux cored wires
When the filler wire is in direct contract with the base metal
Minutes of elapsed time continually run (out of 10 minutes)
Gas metal arc welding

50. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Puddle fluidity
If you dont know this check your phone
Cause flaking - which can clog the liner and contact tube
...