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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 does the term GMAW identify?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
...
Minutes of elapsed time continually run (out of 10 minutes)
Gas metal arc welding

2. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
V groove or U groove
...
Dry ice can form within the flow control openings and cause blockage of shielding gas
Spatter problems and poor weld appearance

3. What is the main purpose of 'slope'?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
To limit the short circuiting current so that spatter is reduced
Wire feed speed
Puddle fluidity

4. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
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
National Electrical Manufactures Association
(DCEP) Direct Current Electrode Positive or Reverse polarity

5. What is a solenoid valve and what actuates it?
Wire feed speed
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
The resistace to electrical current flow increases with it. Causing the electrode to heat
Aluminum wire

6. What 2 organizations designate specifications for GMAW wires?
Duty cycle
DCEP (Direct Current Electrode Positive) Reverse Polarity
The resistace to electrical current flow increases with it. Causing the electrode to heat
AWS and CSA

7. Why is a line heater required when using GMAW?
1/4 inch to 1/2 inch
Dry ice can form within the flow control openings and cause blockage of shielding gas
Higher 26 to 35 arc volts
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

8. What does the abbreviation NEMA stand for?
These terms are quite restrictive and often technically incorrect
If you dont know this check your phone
Generally not as accurate
National Electrical Manufactures Association

9. When is the metal transferred with short circuit transfer?
When the filler wire is in direct contract with the base metal
1/4 inch to 1/2 inch
Spatter problems and poor weld appearance
Penetration and burn - off rate of the electrode

10. In the GMAW process what does voltage control?
Puddle fluidity
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Cause flaking - which can clog the liner and contact tube
12 to 22 arc volts

11. What output on the welding machine is used to rate the duty cycle?
Minutes of elapsed time continually run (out of 10 minutes)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
AWS and CSA
Constant current (CC)

12. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
Cause flaking - which can clog the liner and contact tube
Higher 26 to 35 arc volts
SMAW - GTAW

13. What is the effect of too much slope?
20 to 200 times per second
Insufficient current to melt the wire off cleanly
Cause flaking - which can clog the liner and contact tube
National Electrical Manufactures Association

14. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
Speed of the feed motor and - starting / stopping electrode feed
If you dont know this check your phone
Minutes of elapsed time continually run (out of 10 minutes)

15. What effect does increasing and decreasing the inductance have on the weld?
Penetration and burn - off rate of the electrode
Short- circuiting transfer - Globular transfer - Spray transfer
If you dont know this check your phone
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

16. What controls amperage when using GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
If you dont know this check your phone
Wire feed speed
The time rate of response for the current rise and fall

17. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
Spatter problems and poor weld appearance
Gives arc voltage values to the control system of the feeder
Shielding the molten weld metal from atmospheric contamination

18. Regulators control_____________ flowmeters SHOW____________.
The negative side of a welding unit
Pressure - The rate of flow of a shielding gas
Voltage is the force that overcomes resistance to allow amperage flow
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

19. What are the 2 types of wire feeders available?
The time rate of response for the current rise and fall
20 to 200 times per second
V groove or U groove
Constant- speed wire feeders and Voltage- sennsing wire feeders

20. How are GMAW guns rated?
Pressure vessels and the piping industry
DCEP (Direct Current Electrode Positive) Reverse Polarity
By there current carrying capacity
...

21. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
These terms are quite restrictive and often technically incorrect
By there current carrying capacity
Gives arc voltage values to the control system of the feeder
Controls the rate of flow of a shielding gas to the gun nozzle

22. Draw a typical volt amp curve for a machine that is designed for GMAW
The resistace to electrical current flow increases with it. Causing the electrode to heat
DCEP (Direct Current Electrode Positive) Reverse Polarity
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

23. List the factors that determine the mode of metal transfer
SMAW - GTAW
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Minutes of elapsed time continually run (out of 10 minutes)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

24. What wire are knurled drive rolls most commonly used on?
DCEP (Direct Current Electrode Positive) Reverse Polarity
When the filler wire is in direct contract with the base metal
Constant- speed wire feeders and Voltage- sennsing wire feeders
Flux cored wires

25. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
If you dont know this check your phone
Constant voltage (CV)
AWS and CSA
...

26. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Cause flaking - which can clog the liner and contact tube
Generally not as accurate
V groove or U groove

27. What does a flowmeter do and what does it measure?
Penetration and burn - off rate of the electrode
Controls the rate of flow of a shielding gas to the gun nozzle
Spatter problems and poor weld appearance
Higher 26 to 35 arc volts

28. What controls the wire speed on a voltage sensing wire feeder?
5.8 to 12.5 L/min
Wire feed speed
The Arc voltage
85%

29. List 3 wire drive systems and give a short description of each
Guns
The time rate of response for the current rise and fall
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
Aluminum wire

30. Why is a fiber washer required and what cylinder gas requires it?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Wire feed speed
The negative side of a welding unit
To prevent leakage - Carbon Dioxide (CO2)

31. 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
To prevent drawing of liquid CO2 (Carbon Dioxide)
The time rate of response for the current rise and fall
Minimum distortion due to low heat input

32. What would be an indication that the drive roll pressure is adjusted correctly?
Motor driven generators - Transformer rectifiers - and Inverter designs
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Aluminum wire

33. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
3
Constant current (CC)
(DCEP) Direct Current Electrode Positive or Reverse polarity

34. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Cause flaking - which can clog the liner and contact tube
Higher 26 to 35 arc volts
If you dont know this check your phone
Duty cycle

35. What is the key advantage of short circuiting transfer?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Wire feed speed
Minimum distortion due to low heat input
SMAW - GTAW

36. Why is the term GMAW preferred over MIG or MAG?
(DCEP) Direct Current Electrode Positive or Reverse polarity
15 feet (4.5 meters)
5.8 to 12.5 L/min
These terms are quite restrictive and often technically incorrect

37. Why is globular transfer generally avoided with GMAW?
Welding process that joins metals by heating them with an electric arc
Short- circuiting transfer - Globular transfer - Spray transfer
The time rate of response for the current rise and fall
Spatter problems and poor weld appearance

38. With straight polarity where is 2/3 of the arc energy?
Wire feed speed
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
By there current carrying capacity
The negative side of a welding unit

39. What is the maximum distance that hard wire can be successfully pushed?
Reducing the gas source pressure to a constant working pressure
Puddle fluidity
15 feet (4.5 meters)
3

40. What is the preferred drive roll design for solid wires?
Constant- speed wire feeders and Voltage- sennsing wire feeders
V groove or U groove
Penetration and burn - off rate of the electrode
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

41. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
Controls the rate of flow of a shielding gas to the gun nozzle
DCEP (Direct Current Electrode Positive) Reverse Polarity
When the filler wire is in direct contract with the base metal

42. What is an advantage of pulsed arc transfer with GMAW?
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
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

43. A pull type drive system is usually used on what type of material?
Aluminum wire
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
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

44. What type of power source is commonly used with a voltage sensing wire feeder?
Aluminum wire
Constant current (CC)
Gives arc voltage values to the control system of the feeder
Guns

45. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Duty cycle
Minimum distortion due to low heat input
SMAW - GTAW

46. Why must CO2 cylinders be used in the vertical position?
To prevent leakage - Carbon Dioxide (CO2)
To prevent drawing of liquid CO2 (Carbon Dioxide)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Shielding the molten weld metal from atmospheric contamination

47. What 2 controls are found on a GMAW set- up?
Motor driven generators - Transformer rectifiers - and Inverter designs
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Wire feed speed - Voltage control
20 to 200 times per second

48. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
To prevent leakage - Carbon Dioxide (CO2)
DCEP (Direct Current Electrode Positive) Reverse Polarity
Higher 26 to 35 arc volts
Minutes of elapsed time continually run (out of 10 minutes)

49. List several industries that would use GMAW
The Arc voltage
Minutes of elapsed time continually run (out of 10 minutes)
Pressure vessels and the piping industry
5.8 to 12.5 L/min

50. What is the purpose of the shielding gas used in GMAW?
Speed of the feed motor and - starting / stopping electrode feed
Constant- speed wire feeders and Voltage- sennsing wire feeders
Short- circuiting transfer - Globular transfer - Spray transfer
Shielding the molten weld metal from atmospheric contamination