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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. What effect does increasing and decreasing the inductance have on the weld?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Controls the rate of flow of a shielding gas to the gun nozzle
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Higher 26 to 35 arc volts

2. Why is the term GMAW preferred over MIG or MAG?
20 to 200 times per second
Shielding the molten weld metal from atmospheric contamination
These terms are quite restrictive and often technically incorrect
V groove or U groove

3. What is the preferred drive roll design for solid wires?
Generally not as accurate
V groove or U groove
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
The Arc voltage

4. What current and polarity is generally used with GMAW?
The time rate of response for the current rise and fall
Flux cored wires
Insufficient current to melt the wire off cleanly
DCEP (Direct Current Electrode Positive) Reverse Polarity

5. What is the maximum distance that hard wire can be successfully pushed?
Constant- speed wire feeders and Voltage- sennsing wire feeders
15 feet (4.5 meters)
Duty cycle
Gas metal arc welding

6. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
To prevent drawing of liquid CO2 (Carbon Dioxide)
Constant- speed wire feeders and Voltage- sennsing wire feeders
SMAW - GTAW

7. What happens when the electrode extension is increased?
These terms are quite restrictive and often technically incorrect
The resistace to electrical current flow increases with it. Causing the electrode to heat
Insufficient current to melt the wire off cleanly
To prevent drawing of liquid CO2 (Carbon Dioxide)

8. What is the key advantage of short circuiting transfer?
85%
Minimum distortion due to low heat input
V groove or U groove
Insufficient current to melt the wire off cleanly

9. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Generally not as accurate
(DCEP) Direct Current Electrode Positive or Reverse polarity
Spatter problems and poor weld appearance
Pressure - The rate of flow of a shielding gas

10. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
The negative side of a welding unit
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

11. What is the purpose of the shielding gas used in GMAW?
Short- circuiting transfer - Globular transfer - Spray transfer
Gas metal arc welding
V groove or U groove
Shielding the molten weld metal from atmospheric contamination

12. How are GMAW guns rated?
National Electrical Manufactures Association
Reducing the gas source pressure to a constant working pressure
By there current carrying capacity
Controls the rate of flow of a shielding gas to the gun nozzle

13. What does a flowmeter do and what does it measure?
AWS and CSA
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Reducing the gas source pressure to a constant working pressure
Controls the rate of flow of a shielding gas to the gun nozzle

14. What is an advantage of pulsed arc transfer with GMAW?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Pressure - The rate of flow of a shielding gas
Voltage is the force that overcomes resistance to allow amperage flow
Shielding the molten weld metal from atmospheric contamination

15. Give a brief description of the GMAW process
(DCEP) Direct Current Electrode Positive or Reverse polarity
To prevent leakage - Carbon Dioxide (CO2)
Welding process that joins metals by heating them with an electric arc
Wire feed speed - Voltage control

16. What controls the wire speed on a voltage sensing wire feeder?
Reducing the gas source pressure to a constant working pressure
The negative side of a welding unit
The Arc voltage
Shielding the molten weld metal from atmospheric contamination

17. What does the term GMAW identify?
Flux cored wires
To limit the short circuiting current so that spatter is reduced
Gas metal arc welding
...

18. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
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
Generally not as accurate

19. What power sources are used with the GMAW Process?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Motor driven generators - Transformer rectifiers - and Inverter designs
Gives arc voltage values to the control system of the feeder
3

20. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Short- circuiting transfer - Globular transfer - Spray transfer
Gas metal arc welding
Higher 26 to 35 arc volts

21. Why is globular transfer generally avoided with GMAW?
The negative side of a welding unit
Spatter problems and poor weld appearance
Generally not as accurate
1/4 inch to 1/2 inch

22. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
Voltage is the force that overcomes resistance to allow amperage flow
Gives arc voltage values to the control system of the feeder
Pressure vessels and the piping industry

23. In the GMAW process what does voltage control?
Guns
The negative side of a welding unit
Puddle fluidity
20 to 200 times per second

24. What is a typical flow rate of CO2 for short circuit transfer?
National Electrical Manufactures Association
5.8 to 12.5 L/min
Gives arc voltage values to the control system of the feeder
The Arc voltage

25. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Spatter problems and poor weld appearance
To prevent leakage - Carbon Dioxide (CO2)
...

26. How many times per second does short circuiting take place?
Pressure - The rate of flow of a shielding gas
These terms are quite restrictive and often technically incorrect
20 to 200 times per second
Shielding the molten weld metal from atmospheric contamination

27. 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
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
...
Spatter problems and poor weld appearance

28. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
Aluminum wire
Pressure vessels and the piping industry
15 feet (4.5 meters)

29. A pull type drive system is usually used on what type of material?
Flux cored wires
If you dont know this check your phone
Aluminum wire
Guns

30. Regulators control_____________ flowmeters SHOW____________.
Gives arc voltage values to the control system of the feeder
1/4 inch to 1/2 inch
If you dont know this check your phone
Pressure - The rate of flow of a shielding gas

31. What is a solenoid valve and what actuates it?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Duty cycle
Pressure - The rate of flow of a shielding gas

32. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Pressure vessels and the piping industry
Insufficient current to melt the wire off cleanly
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
85%

33. What would be an indication that the drive roll pressure is adjusted correctly?
Penetration and burn - off rate of the electrode
85%
Short- circuiting transfer - Globular transfer - Spray transfer
Wire feeds smoothly (yet will slip should a problem occur in the gun)

34. List 3 forms compressed gases may be supplied for welding
Motor driven generators - Transformer rectifiers - and Inverter designs
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
1/4 inch to 1/2 inch
Higher 26 to 35 arc volts

35. What controls amperage when using GMAW?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Wire feed speed
To limit the short circuiting current so that spatter is reduced
Pressure - The rate of flow of a shielding gas

36. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Wire feed speed - Voltage control
Generally not as accurate
3
Wire feeds smoothly (yet will slip should a problem occur in the gun)

37. What is the main purpose of 'slope'?
Penetration and burn - off rate of the electrode
1/4 inch to 1/2 inch
To limit the short circuiting current so that spatter is reduced
If you dont know this check your phone

38. What is another term for electrode holders for GMAW?
Constant voltage (CV)
Guns
85%
Constant current (CC)

39. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Cause flaking - which can clog the liner and contact tube
Aluminum wire
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

40. Draw a typical volt amp curve for a machine that is designed for GMAW
If you dont know this check your phone
15 feet (4.5 meters)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Shielding the molten weld metal from atmospheric contamination

41. List 3 wire drive systems and give a short description of each
When the filler wire is in direct contract with the base metal
These terms are quite restrictive and often technically incorrect
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
AWS and CSA

42. When is the metal transferred with short circuit transfer?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Generally not as accurate
When the filler wire is in direct contract with the base metal
To limit the short circuiting current so that spatter is reduced

43. What type of power source is commonly used with a voltage sensing wire feeder?
Minutes of elapsed time continually run (out of 10 minutes)
Gives arc voltage values to the control system of the feeder
20 to 200 times per second
Constant current (CC)

44. In the GMAW process what does amperage control?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Motor driven generators - Transformer rectifiers - and Inverter designs
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Penetration and burn - off rate of the electrode

45. What processes are constant current (CC) power sources designed to be used with?
V groove or U groove
SMAW - GTAW
1/4 inch to 1/2 inch
If you dont know this check your phone

46. What wire are knurled drive rolls most commonly used on?
Gives arc voltage values to the control system of the feeder
Flux cored wires
By there current carrying capacity
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

47. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
These terms are quite restrictive and often technically incorrect
1/4 inch to 1/2 inch
15 feet (4.5 meters)

48. List the factors that determine the mode of metal transfer
These terms are quite restrictive and often technically incorrect
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
The negative side of a welding unit
Generally not as accurate

49. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
Cause flaking - which can clog the liner and contact tube
Higher 26 to 35 arc volts
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

50. What is the effect of too much slope?
Penetration and burn - off rate of the electrode
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Insufficient current to melt the wire off cleanly
5.8 to 12.5 L/min