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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. List the basic equipment requirements for the GMAW process
...
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Shielding the molten weld metal from atmospheric contamination
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2. Why is a fiber washer required and what cylinder gas requires it?
Cause flaking - which can clog the liner and contact tube
The resistace to electrical current flow increases with it. Causing the electrode to heat
To prevent leakage - Carbon Dioxide (CO2)
These terms are quite restrictive and often technically incorrect

3. Why is globular transfer generally avoided with GMAW?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Constant current (CC)
Spatter problems and poor weld appearance
Insufficient current to melt the wire off cleanly

4. What effect does increasing and decreasing the inductance have on the weld?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
SMAW - GTAW
Guns
12 to 22 arc volts

5. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
20 to 200 times per second
...
Shielding the molten weld metal from atmospheric contamination
Short- circuiting transfer - Globular transfer - Spray transfer

6. Draw a typical volt amp curve for a machine that is designed for GMAW
Wire feed speed - Voltage control
Constant voltage (CV)
Cause flaking - which can clog the liner and contact tube
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7. List the three methods of metal transfer with GMAW
Guns
3
Short- circuiting transfer - Globular transfer - Spray transfer
The negative side of a welding unit

8. What 2 organizations designate specifications for GMAW wires?
AWS and CSA
1/4 inch to 1/2 inch
Flux cored wires
Insufficient current to melt the wire off cleanly

9. 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
Constant voltage (CV)
The Arc voltage
Puddle fluidity

10. What controls the wire speed on a voltage sensing wire feeder?
Wire feed speed - Voltage control
Puddle fluidity
To prevent leakage - Carbon Dioxide (CO2)
The Arc voltage

11. List the factors that determine the mode of metal transfer
Guns
Voltage is the force that overcomes resistance to allow amperage flow
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Spatter problems and poor weld appearance

12. A pull type drive system is usually used on what type of material?
Aluminum wire
When the filler wire is in direct contract with the base metal
Gives arc voltage values to the control system of the feeder
By there current carrying capacity

13. List several industries that would use GMAW
The time rate of response for the current rise and fall
Pressure vessels and the piping industry
Spatter problems and poor weld appearance
DCEP (Direct Current Electrode Positive) Reverse Polarity

14. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Dry ice can form within the flow control openings and cause blockage of shielding gas
(DCEP) Direct Current Electrode Positive or Reverse polarity
By there current carrying capacity
V groove or U groove

15. What output on the welding machine is used to rate the duty cycle?
V groove or U groove
(DCEP) Direct Current Electrode Positive or Reverse polarity
Higher 26 to 35 arc volts
Minutes of elapsed time continually run (out of 10 minutes)

16. What 2 controls are found on a GMAW set- up?
When the filler wire is in direct contract with the base metal
5.8 to 12.5 L/min
Puddle fluidity
Wire feed speed - Voltage control

17. What does voltage do in an electrical circuit?
The Arc voltage
1/4 inch to 1/2 inch
National Electrical Manufactures Association
Voltage is the force that overcomes resistance to allow amperage flow

18. Why must CO2 cylinders be used in the vertical position?
(DCEP) Direct Current Electrode Positive or Reverse polarity
To prevent drawing of liquid CO2 (Carbon Dioxide)
Constant current (CC)
National Electrical Manufactures Association

19. How many times per second does short circuiting take place?
3
Gas metal arc welding
AWS and CSA
20 to 200 times per second

20. What processes are constant current (CC) power sources designed to be used with?
Pressure vessels and the piping industry
By there current carrying capacity
The time rate of response for the current rise and fall
SMAW - GTAW

21. What is the required arc voltage used for short circuit transfer?
Constant voltage (CV)
Spatter problems and poor weld appearance
The time rate of response for the current rise and fall
12 to 22 arc volts

22. List 3 forms compressed gases may be supplied for welding
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
These terms are quite restrictive and often technically incorrect
Speed of the feed motor and - starting / stopping electrode feed
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

23. What is another term for electrode holders for 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
Pressure vessels and the piping industry
Guns
12 to 22 arc volts

24. What is a typical flow rate of CO2 for short circuit transfer?
Insufficient current to melt the wire off cleanly
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
5.8 to 12.5 L/min
To prevent leakage - Carbon Dioxide (CO2)

25. In the GMAW process what does amperage control?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Penetration and burn - off rate of the electrode
V groove or U groove
The resistace to electrical current flow increases with it. Causing the electrode to heat

26. Give a description of 'pinch effect'
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
Constant voltage (CV)

27. List 3 wire drive systems and give a short description of each
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
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
Controls the rate of flow of a shielding gas to the gun nozzle
To prevent leakage - Carbon Dioxide (CO2)

28. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
The Arc voltage
Gives arc voltage values to the control system of the feeder
Minutes of elapsed time continually run (out of 10 minutes)
85%

29. When is the metal transferred with short circuit transfer?
Minimum distortion due to low heat input
1/4 inch to 1/2 inch
Motor driven generators - Transformer rectifiers - and Inverter designs
When the filler wire is in direct contract with the base metal

30. A 10 minute cycle of welding time vs cooling time a given machine can handle.
12 to 22 arc volts
Duty cycle
15 feet (4.5 meters)
Speed of the feed motor and - starting / stopping electrode feed

31. What is a solenoid valve and what actuates it?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Pressure vessels and the piping industry
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

32. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
...
Voltage is the force that overcomes resistance to allow amperage flow
Gives arc voltage values to the control system of the feeder
3

33. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
12 to 22 arc volts
Cause flaking - which can clog the liner and contact tube
Motor driven generators - Transformer rectifiers - and Inverter designs
Insufficient current to melt the wire off cleanly

34. What are the 2 types of wire feeders available?
Insufficient current to melt the wire off cleanly
DCEP (Direct Current Electrode Positive) Reverse Polarity
Constant- speed wire feeders and Voltage- sennsing wire feeders
Guns

35. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
Gas metal arc welding
Welding process that joins metals by heating them with an electric arc
Wire feeds smoothly (yet will slip should a problem occur in the gun)

36. Why is the term GMAW preferred over MIG or MAG?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
V groove or U groove
Aluminum wire
These terms are quite restrictive and often technically incorrect

37. What is the purpose of a regulator and what does it indicate on its gauges?
When the filler wire is in direct contract with the base metal
5.8 to 12.5 L/min
Pressure - The rate of flow of a shielding gas
Reducing the gas source pressure to a constant working pressure

38. What controls amperage when using GMAW?
Wire feed speed
5.8 to 12.5 L/min
The resistace to electrical current flow increases with it. Causing the electrode to heat
...

39. 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
5.8 to 12.5 L/min
Insufficient current to melt the wire off cleanly
When the filler wire is in direct contract with the base metal

40. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
By there current carrying capacity
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

41. What is the maximum distance that hard wire can be successfully pushed?
5.8 to 12.5 L/min
Shielding the molten weld metal from atmospheric contamination
15 feet (4.5 meters)
Speed of the feed motor and - starting / stopping electrode feed

42. 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
Gives arc voltage values to the control system of the feeder
National Electrical Manufactures Association

43. What does inductance control?
...
Controls the rate of flow of a shielding gas to the gun nozzle
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

44. Give a brief description of the GMAW process
Wire feed speed
Welding process that joins metals by heating them with an electric arc
12 to 22 arc volts
Wire feed speed - Voltage control

45. How are GMAW guns rated?
SMAW - GTAW
By there current carrying capacity
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Wire feed speed

46. What is the main purpose of 'slope'?
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 limit the short circuiting current so that spatter is reduced
Wire feed speed

47. What does the term GMAW identify?
Reducing the gas source pressure to a constant working pressure
Gas metal arc welding
Speed of the feed motor and - starting / stopping electrode feed
Constant voltage (CV)

48. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
To limit the short circuiting current so that spatter is reduced
Constant current (CC)
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
If you dont know this check your phone

49. What wire are knurled drive rolls most commonly used on?
V groove or U groove
Flux cored wires
3
AWS and CSA

50. Why is a line heater required when using GMAW?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Penetration and burn - off rate of the electrode
Dry ice can form within the flow control openings and cause blockage of shielding gas