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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.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

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. Why is a line heater required when using GMAW?
Wire feed speed - Voltage control
Duty cycle
Dry ice can form within the flow control openings and cause blockage of shielding gas
5.8 to 12.5 L/min

2. List 3 wire drive systems and give a short description of each
Guns
By there current carrying capacity
12 to 22 arc volts
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. When is the metal transferred with short circuit transfer?
(DCEP) Direct Current Electrode Positive or Reverse polarity
When the filler wire is in direct contract with the base metal
Short- circuiting transfer - Globular transfer - Spray transfer
To prevent leakage - Carbon Dioxide (CO2)

4. What is the key advantage of short circuiting transfer?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Minimum distortion due to low heat input
Short- circuiting transfer - Globular transfer - Spray transfer
Wire feeds smoothly (yet will slip should a problem occur in the gun)

5. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
When the filler wire is in direct contract with the base metal
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Cause flaking - which can clog the liner and contact tube

6. What does the abbreviation NEMA stand for?
The time rate of response for the current rise and fall
National Electrical Manufactures Association
Aluminum wire
AWS and CSA

7. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
Reducing the gas source pressure to a constant working pressure
3
The Arc voltage

8. What is the required arc voltage used for short circuit transfer?
To limit the short circuiting current so that spatter is reduced
Voltage is the force that overcomes resistance to allow amperage flow
12 to 22 arc volts
To prevent drawing of liquid CO2 (Carbon Dioxide)

9. A pull type drive system is usually used on what type of material?
Aluminum wire
Pressure - The rate of flow of a shielding gas
Gas metal arc welding
Dry ice can form within the flow control openings and cause blockage of shielding gas

10. In the GMAW process what does voltage control?
The time rate of response for the current rise and fall
Gas metal arc welding
The Arc voltage
Puddle fluidity

11. What is an advantage of pulsed arc transfer with GMAW?
12 to 22 arc volts
These terms are quite restrictive and often technically incorrect
Pressure vessels and the piping industry
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

12. List the factors that determine the mode of metal transfer
Wire feed speed - Voltage control
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Insufficient current to melt the wire off cleanly

13. List 3 forms compressed gases may be supplied for welding
Aluminum wire
V groove or U groove
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Short- circuiting transfer - Globular transfer - Spray transfer

14. What does a flowmeter do and what does it measure?
Puddle fluidity
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
The time rate of response for the current rise and fall
Controls the rate of flow of a shielding gas to the gun nozzle

15. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
Voltage is the force that overcomes resistance to allow amperage flow
The time rate of response for the current rise and fall
20 to 200 times per second

16. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
12 to 22 arc volts
Shielding the molten weld metal from atmospheric contamination
...

17. 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
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
To prevent leakage - Carbon Dioxide (CO2)

18. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
The Arc voltage
Insufficient current to melt the wire off cleanly
When the filler wire is in direct contract with the base metal

19. What is a solenoid valve and what actuates it?
Guns
Insufficient current to melt the wire off cleanly
AWS and CSA
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

20. What 2 organizations designate specifications for GMAW wires?
20 to 200 times per second
85%
Reducing the gas source pressure to a constant working pressure
AWS and CSA

21. List several industries that would use GMAW
The time rate of response for the current rise and fall
Flux cored wires
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

22. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Spatter problems and poor weld appearance
Gives arc voltage values to the control system of the feeder
...
Reducing the gas source pressure to a constant working pressure

23. What wire are knurled drive rolls most commonly used on?
V groove or U groove
Welding process that joins metals by heating them with an electric arc
Flux cored wires
Cause flaking - which can clog the liner and contact tube

24. Give a brief description of the GMAW process
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
To prevent drawing of liquid CO2 (Carbon Dioxide)
Welding process that joins metals by heating them with an electric arc
Constant current (CC)

25. What current and polarity is generally used with GMAW?
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
15 feet (4.5 meters)
Motor driven generators - Transformer rectifiers - and Inverter designs
DCEP (Direct Current Electrode Positive) Reverse Polarity

26. Draw a typical volt amp curve for a machine that is designed for GMAW
Spatter problems and poor weld appearance
If you dont know this check your phone
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Constant current (CC)

27. What 2 controls are found on a GMAW set- up?
Spatter problems and poor weld appearance
Speed of the feed motor and - starting / stopping electrode feed
Wire feed speed - Voltage control
When the filler wire is in direct contract with the base metal

28. 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
1/4 inch to 1/2 inch
(DCEP) Direct Current Electrode Positive or Reverse polarity
Welding process that joins metals by heating them with an electric arc

29. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
Constant- speed wire feeders and Voltage- sennsing wire feeders
V groove or U groove
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

30. What is the main purpose of 'slope'?
By there current carrying capacity
Motor driven generators - Transformer rectifiers - and Inverter designs
To limit the short circuiting current so that spatter is reduced
Wire feed speed

31. What does the term GMAW identify?
If you dont know this check your phone
Constant current (CC)
These terms are quite restrictive and often technically incorrect
Gas metal arc welding

32. What does voltage do in an electrical circuit?
Shielding the molten weld metal from atmospheric contamination
V groove or U groove
85%
Voltage is the force that overcomes resistance to allow amperage flow

33. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
Cause flaking - which can clog the liner and contact tube
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
SMAW - GTAW

34. What is the purpose of the shielding gas used in GMAW?
Motor driven generators - Transformer rectifiers - and Inverter designs
The time rate of response for the current rise and fall
Duty cycle
Shielding the molten weld metal from atmospheric contamination

35. Regulators control_____________ flowmeters SHOW____________.
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Pressure - The rate of flow of a shielding gas
Gas metal arc welding
National Electrical Manufactures Association

36. What type of power source is commonly used with a voltage sensing wire feeder?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Wire feed speed - Voltage control
Constant current (CC)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

37. Give a description of 'pinch effect'
15 feet (4.5 meters)
Gas metal arc welding
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Aluminum wire

38. List the basic equipment requirements for the GMAW process
Gives arc voltage values to the control system of the feeder
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
If you dont know this check your phone
Wire feeds smoothly (yet will slip should a problem occur in the gun)

39. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
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
When the filler wire is in direct contract with the base metal

40. What is the effect of too much slope?
3
To prevent leakage - Carbon Dioxide (CO2)
Dry ice can form within the flow control openings and cause blockage of shielding gas
Insufficient current to melt the wire off cleanly

41. What is another term for electrode holders for GMAW?
Shielding the molten weld metal from atmospheric contamination
Minutes of elapsed time continually run (out of 10 minutes)
Guns
To limit the short circuiting current so that spatter is reduced

42. What is the preferred drive roll design for solid wires?
V groove or U groove
Shielding the molten weld metal from atmospheric contamination
Welding process that joins metals by heating them with an electric arc
3

43. What is the maximum distance that hard wire can be successfully pushed?
Constant voltage (CV)
If you dont know this check your phone
15 feet (4.5 meters)
AWS and CSA

44. Why must CO2 cylinders be used in the vertical position?
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
Insufficient current to melt the wire off cleanly
To prevent drawing of liquid CO2 (Carbon Dioxide)

45. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
AWS and CSA
(DCEP) Direct Current Electrode Positive or Reverse polarity
Puddle fluidity
Shielding the molten weld metal from atmospheric contamination

46. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
Gas metal arc welding
...
Constant- speed wire feeders and Voltage- sennsing wire feeders

47. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
Constant current (CC)
SMAW - GTAW
Voltage is the force that overcomes resistance to allow amperage flow

48. What power sources are used with the GMAW Process?
Short- circuiting transfer - Globular transfer - Spray transfer
Motor driven generators - Transformer rectifiers - and Inverter designs
20 to 200 times per second
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

49. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
The negative side of a welding unit
Wire feed speed
5.8 to 12.5 L/min

50. How are GMAW guns rated?
20 to 200 times per second
Aluminum wire
AWS and CSA
By there current carrying capacity