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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?
...
Flux cored wires
Pressure vessels and the piping industry
Shielding the molten weld metal from atmospheric contamination

2. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Motor driven generators - Transformer rectifiers - and Inverter designs
Higher 26 to 35 arc volts
When the filler wire is in direct contract with the base metal
(DCEP) Direct Current Electrode Positive or Reverse polarity

3. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Wire feed speed - Voltage control
20 to 200 times per second
85%

4. What does a flowmeter do and what does it measure?
(DCEP) Direct Current Electrode Positive or Reverse polarity
85%
To prevent drawing of liquid CO2 (Carbon Dioxide)
Controls the rate of flow of a shielding gas to the gun nozzle

5. Why must CO2 cylinders be used in the vertical position?
Duty cycle
Constant voltage (CV)
To prevent drawing of liquid CO2 (Carbon Dioxide)
If you dont know this check your phone

6. What does inductance control?
Dry ice can form within the flow control openings and cause blockage of shielding gas
The time rate of response for the current rise and fall
Higher 26 to 35 arc volts
12 to 22 arc volts

7. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
Duty cycle
When the filler wire is in direct contract with the base metal
Shielding the molten weld metal from atmospheric contamination

8. What type of power source is used with a constant speed wire feeder?
Generally not as accurate
Wire feeds smoothly (yet will slip should a problem occur in the gun)
When the filler wire is in direct contract with the base metal
Constant voltage (CV)

9. What effect does increasing and decreasing the inductance have on the weld?
Dry ice can form within the flow control openings and cause blockage of shielding gas
85%
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Puddle fluidity

10. Regulators control_____________ flowmeters SHOW____________.
Pressure - The rate of flow of a shielding gas
Generally not as accurate
Voltage is the force that overcomes resistance to allow amperage flow
Wire feed speed - Voltage control

11. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
Motor driven generators - Transformer rectifiers - and Inverter designs
Wire feed speed - Voltage control
Constant- speed wire feeders and Voltage- sennsing wire feeders

12. With straight polarity where is 2/3 of the arc energy?
Higher 26 to 35 arc volts
Wire feed speed - Voltage control
Motor driven generators - Transformer rectifiers - and Inverter designs
The negative side of a welding unit

13. A pull type drive system is usually used on what type of material?
Dry ice can form within the flow control openings and cause blockage of shielding gas
85%
SMAW - GTAW
Aluminum wire

14. What is the preferred drive roll design for solid wires?
V groove or U groove
Welding process that joins metals by heating them with an electric arc
15 feet (4.5 meters)
The time rate of response for the current rise and fall

15. What is the required arc voltage used for short circuit transfer?
Flux cored wires
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
12 to 22 arc volts
Generally not as accurate

16. What processes are constant current (CC) power sources designed to be used with?
Voltage is the force that overcomes resistance to allow amperage flow
SMAW - GTAW
Insufficient current to melt the wire off cleanly
To prevent drawing of liquid CO2 (Carbon Dioxide)

17. In the GMAW process what does voltage control?
Spatter problems and poor weld appearance
Minimum distortion due to low heat input
Puddle fluidity
Gives arc voltage values to the control system of the feeder

18. What is a typical flow rate of CO2 for short circuit transfer?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
85%
15 feet (4.5 meters)
5.8 to 12.5 L/min

19. What does voltage do in an electrical circuit?
When the filler wire is in direct contract with the base metal
Voltage is the force that overcomes resistance to allow amperage flow
(DCEP) Direct Current Electrode Positive or Reverse polarity
Wire feed speed - Voltage control

20. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Gives arc voltage values to the control system of the feeder
Constant- speed wire feeders and Voltage- sennsing wire feeders
Duty cycle
Puddle fluidity

21. What does the term GMAW identify?
Aluminum wire
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Gas metal arc welding
Minutes of elapsed time continually run (out of 10 minutes)

22. What is the purpose of a regulator and what does it indicate on its gauges?
1/4 inch to 1/2 inch
Minutes of elapsed time continually run (out of 10 minutes)
Reducing the gas source pressure to a constant working pressure
Spatter problems and poor weld appearance

23. When is the metal transferred with short circuit transfer?
20 to 200 times per second
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
85%
When the filler wire is in direct contract with the base metal

24. List several industries that would use GMAW
If you dont know this check your phone
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
Puddle fluidity

25. List the three methods of metal transfer with GMAW
1/4 inch to 1/2 inch
...
Short- circuiting transfer - Globular transfer - Spray transfer
Minutes of elapsed time continually run (out of 10 minutes)

26. In the GMAW process what does amperage control?
Welding process that joins metals by heating them with an electric arc
Penetration and burn - off rate of the electrode
Duty cycle
85%

27. Why is the term GMAW preferred over MIG or MAG?
Shielding the molten weld metal from atmospheric contamination
These terms are quite restrictive and often technically incorrect
Minutes of elapsed time continually run (out of 10 minutes)
The resistace to electrical current flow increases with it. Causing the electrode to heat

28. What is an advantage of pulsed arc transfer with GMAW?
When the filler wire is in direct contract with the base metal
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
85%
Generally not as accurate

29. 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
The negative side of a welding unit
V groove or U groove
Constant current (CC)

30. What would be an indication that the drive roll pressure is adjusted correctly?
To prevent drawing of liquid CO2 (Carbon Dioxide)
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
Wire feeds smoothly (yet will slip should a problem occur in the gun)
1/4 inch to 1/2 inch

31. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
...
If you dont know this check your phone
12 to 22 arc volts
DCEP (Direct Current Electrode Positive) Reverse Polarity

32. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
Dry ice can form within the flow control openings and cause blockage of shielding gas
DCEP (Direct Current Electrode Positive) Reverse Polarity
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

33. 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
Minimum distortion due to low heat input
The negative side of a welding unit
By there current carrying capacity

34. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Constant- speed wire feeders and Voltage- sennsing wire feeders
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
3

35. 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
National Electrical Manufactures Association
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Guns

36. What 2 controls are found on a GMAW set- up?
Wire feed speed - Voltage control
SMAW - GTAW
Pressure - The rate of flow of a shielding gas
Constant current (CC)

37. What controls amperage when using GMAW?
If you dont know this check your phone
Wire feed speed
Constant current (CC)
Dry ice can form within the flow control openings and cause blockage of shielding gas

38. What is the maximum distance that hard wire can be successfully pushed?
When the filler wire is in direct contract with the base metal
85%
Cause flaking - which can clog the liner and contact tube
15 feet (4.5 meters)

39. What power sources are used with the GMAW Process?
Shielding the molten weld metal from atmospheric contamination
SMAW - GTAW
Motor driven generators - Transformer rectifiers - and Inverter designs
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

40. What is the key advantage of short circuiting transfer?
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
Minimum distortion due to low heat input
Shielding the molten weld metal from atmospheric contamination
Penetration and burn - off rate of the electrode

41. List the basic equipment requirements for the GMAW process
Gas metal arc welding
Shielding the molten weld metal from atmospheric contamination
If you dont know this check your phone
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

42. List the factors that determine the mode of metal transfer
The resistace to electrical current flow increases with it. Causing the electrode to heat
If you dont know this check your phone
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
National Electrical Manufactures Association

43. Give a description of 'pinch effect'
Constant- speed wire feeders and Voltage- sennsing wire feeders
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Guns
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

44. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Puddle fluidity
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Constant voltage (CV)
Generally not as accurate

45. Draw a typical volt amp curve for a machine that is designed for GMAW
If you dont know this check your phone
To prevent leakage - Carbon Dioxide (CO2)
Short- circuiting transfer - Globular transfer - Spray transfer
Constant voltage (CV)

46. What wire are knurled drive rolls most commonly used on?
Reducing the gas source pressure to a constant working pressure
Constant voltage (CV)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Flux cored wires

47. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Guns
Voltage is the force that overcomes resistance to allow amperage flow
Cause flaking - which can clog the liner and contact tube

48. What is the main purpose of 'slope'?
By there current carrying capacity
Constant voltage (CV)
If you dont know this check your phone
To limit the short circuiting current so that spatter is reduced

49. List 3 forms compressed gases may be supplied for welding
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
To prevent leakage - Carbon Dioxide (CO2)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

50. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Pressure - The rate of flow of a shielding gas
Pressure vessels and the piping industry
Dry ice can form within the flow control openings and cause blockage of shielding gas