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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. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
National Electrical Manufactures Association
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Minimum distortion due to low heat input

2. What current and polarity is generally used with GMAW?
3
DCEP (Direct Current Electrode Positive) Reverse Polarity
To prevent leakage - Carbon Dioxide (CO2)
Welding process that joins metals by heating them with an electric arc

3. With straight polarity where is 2/3 of the arc energy?
AWS and CSA
Shielding the molten weld metal from atmospheric contamination
The negative side of a welding unit
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

4. What 2 controls are found on a GMAW set- up?
Wire feed speed - Voltage control
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

5. How are GMAW guns rated?
By there current carrying capacity
Higher 26 to 35 arc volts
Constant current (CC)
Guns

6. Draw a typical volt amp curve for a machine that is designed for GMAW
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Guns
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Constant current (CC)

7. List 3 forms compressed gases may be supplied for welding
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Flux cored wires
Guns
Reducing the gas source pressure to a constant working pressure

8. When is the metal transferred with short circuit transfer?
Higher 26 to 35 arc volts
When the filler wire is in direct contract with the base metal
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
To limit the short circuiting current so that spatter is reduced

9. What power sources are used with the GMAW Process?
Controls the rate of flow of a shielding gas to the gun nozzle
Motor driven generators - Transformer rectifiers - and Inverter designs
AWS and CSA
Penetration and burn - off rate of the electrode

10. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
To prevent leakage - Carbon Dioxide (CO2)
Welding process that joins metals by heating them with an electric arc
Pressure vessels and the piping industry

11. What type of power source is used with a constant speed wire feeder?
National Electrical Manufactures Association
Constant voltage (CV)
Wire feed speed - Voltage control
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

12. What is the preferred drive roll design for solid wires?
V groove or U groove
3
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
The negative side of a welding unit

13. What output on the welding machine is used to rate the duty cycle?
Higher 26 to 35 arc volts
Shielding the molten weld metal from atmospheric contamination
Minutes of elapsed time continually run (out of 10 minutes)
5.8 to 12.5 L/min

14. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
The Arc voltage
...
V groove or U groove
Wire feed speed - Voltage control

15. What is the maximum distance that hard wire can be successfully pushed?
Short- circuiting transfer - Globular transfer - Spray transfer
Cause flaking - which can clog the liner and contact tube
15 feet (4.5 meters)
1/4 inch to 1/2 inch

16. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
These terms are quite restrictive and often technically incorrect
AWS and CSA
Short- circuiting transfer - Globular transfer - Spray transfer

17. Why must CO2 cylinders be used in the vertical position?
DCEP (Direct Current Electrode Positive) Reverse Polarity
To prevent drawing of liquid CO2 (Carbon Dioxide)
SMAW - GTAW
Higher 26 to 35 arc volts

18. What wire are knurled drive rolls most commonly used on?
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
Flux cored wires
Aluminum wire

19. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
The negative side of a welding unit
National Electrical Manufactures Association
Constant- speed wire feeders and Voltage- sennsing wire feeders

20. What is an advantage of pulsed arc transfer with GMAW?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Minimum distortion due to low heat input
AWS and CSA

21. Why is globular transfer generally avoided with GMAW?
Cause flaking - which can clog the liner and contact tube
Spatter problems and poor weld appearance
SMAW - GTAW
To prevent leakage - Carbon Dioxide (CO2)

22. What effect does increasing and decreasing the inductance have on the weld?
3
Constant voltage (CV)
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
To limit the short circuiting current so that spatter is reduced

23. How many times per second does short circuiting take place?
Speed of the feed motor and - starting / stopping electrode feed
20 to 200 times per second
...
Gives arc voltage values to the control system of the feeder

24. What does the wire feeder control?
Constant current (CC)
Speed of the feed motor and - starting / stopping electrode feed
Higher 26 to 35 arc volts
Insufficient current to melt the wire off cleanly

25. What processes are constant current (CC) power sources designed to be used with?
1/4 inch to 1/2 inch
Welding process that joins metals by heating them with an electric arc
The resistace to electrical current flow increases with it. Causing the electrode to heat
SMAW - GTAW

26. What does the abbreviation NEMA stand for?
Short- circuiting transfer - Globular transfer - Spray transfer
National Electrical Manufactures Association
Controls the rate of flow of a shielding gas to the gun nozzle
Reducing the gas source pressure to a constant working pressure

27. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Generally not as accurate
Wire feed speed - Voltage control

28. What is the required arc voltage used for short circuit transfer?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Minimum distortion due to low heat input
12 to 22 arc volts

29. 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
Constant current (CC)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

30. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
If you dont know this check your phone
Higher 26 to 35 arc volts
The resistace to electrical current flow increases with it. Causing the electrode to heat
Dry ice can form within the flow control openings and cause blockage of shielding gas

31. 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
To prevent leakage - Carbon Dioxide (CO2)
Reducing the gas source pressure to a constant working pressure
To prevent drawing of liquid CO2 (Carbon Dioxide)

32. 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
If you dont know this check your phone
3
Short- circuiting transfer - Globular transfer - Spray transfer

33. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
5.8 to 12.5 L/min
(DCEP) Direct Current Electrode Positive or Reverse polarity
DCEP (Direct Current Electrode Positive) Reverse Polarity
12 to 22 arc volts

34. In the GMAW process what does voltage control?
Puddle fluidity
Generally not as accurate
3
Minimum distortion due to low heat input

35. What 2 organizations designate specifications for GMAW wires?
To prevent leakage - Carbon Dioxide (CO2)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
AWS and CSA
When the filler wire is in direct contract with the base metal

36. What is the key advantage of short circuiting transfer?
Short- circuiting transfer - Globular transfer - Spray transfer
Pressure vessels and the piping industry
5.8 to 12.5 L/min
Minimum distortion due to low heat input

37. 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
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
Aluminum wire

38. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
V groove or U groove
Speed of the feed motor and - starting / stopping electrode feed
If you dont know this check your phone

39. Regulators control_____________ flowmeters SHOW____________.
1/4 inch to 1/2 inch
Pressure - The rate of flow of a shielding gas
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Gives arc voltage values to the control system of the feeder

40. What is another term for electrode holders for GMAW?
Guns
Minimum distortion due to low heat input
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Generally not as accurate

41. What is a solenoid valve and what actuates it?
Minutes of elapsed time continually run (out of 10 minutes)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
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

42. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Wire feed speed
Cause flaking - which can clog the liner and contact tube
V groove or U groove
Flux cored wires

43. List several industries that would use GMAW
Pressure vessels and the piping industry
Reducing the gas source pressure to a constant working pressure
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
These terms are quite restrictive and often technically incorrect

44. What does the term GMAW identify?
Motor driven generators - Transformer rectifiers - and Inverter designs
Gives arc voltage values to the control system of the feeder
Gas metal arc welding
Shielding the molten weld metal from atmospheric contamination

45. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
SMAW - GTAW
85%

46. What is the recommended electrode stick- out for .035 solid wire?
Gas metal arc welding
Pressure vessels and the piping industry
12 to 22 arc volts
1/4 inch to 1/2 inch

47. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
Penetration and burn - off rate of the electrode
Shielding the molten weld metal from atmospheric contamination
Puddle fluidity

48. List the factors that determine the mode of metal transfer
Generally not as accurate
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
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

49. Give a description of 'pinch effect'
Minutes of elapsed time continually run (out of 10 minutes)
Short- circuiting transfer - Globular transfer - Spray transfer
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

50. What would be an indication that the drive roll pressure is adjusted correctly?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
...
Reducing the gas source pressure to a constant working pressure
SMAW - GTAW