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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 wire are knurled drive rolls most commonly used on?
Guns
Welding process that joins metals by heating them with an electric arc
Flux cored wires
When the filler wire is in direct contract with the base metal

2. Draw a typical volt amp curve for a machine that is designed for GMAW
Constant voltage (CV)
Welding process that joins metals by heating them with an electric arc
...
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3. 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
1/4 inch to 1/2 inch
Pressure - The rate of flow of a shielding gas
The time rate of response for the current rise and fall

4. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Duty cycle
Puddle fluidity
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

5. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
To prevent drawing of liquid CO2 (Carbon Dioxide)
When the filler wire is in direct contract with the base metal
15 feet (4.5 meters)

6. List the three methods of metal transfer with GMAW
To prevent drawing of liquid CO2 (Carbon Dioxide)
Short- circuiting transfer - Globular transfer - Spray transfer
Insufficient current to melt the wire off cleanly
Gives arc voltage values to the control system of the feeder

7. A pull type drive system is usually used on what type of material?
Voltage is the force that overcomes resistance to allow amperage flow
Aluminum wire
The Arc voltage
The negative side of a welding unit

8. What is the purpose of the shielding gas used in GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
V groove or U groove
Shielding the molten weld metal from atmospheric contamination

9. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Cause flaking - which can clog the liner and contact tube
Speed of the feed motor and - starting / stopping electrode feed
By there current carrying capacity
AWS and CSA

10. With straight polarity where is 2/3 of the arc energy?
To prevent leakage - Carbon Dioxide (CO2)
Constant voltage (CV)
The negative side of a welding unit
When the filler wire is in direct contract with the base metal

11. What effect does increasing and decreasing the inductance have on the weld?
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(DCEP) Direct Current Electrode Positive or Reverse polarity
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

12. List 3 forms compressed gases may be supplied for welding
15 feet (4.5 meters)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Controls the rate of flow of a shielding gas to the gun nozzle
Pressure - The rate of flow of a shielding gas

13. What does inductance control?
Aluminum wire
The time rate of response for the current rise and fall
Motor driven generators - Transformer rectifiers - and Inverter designs
Constant current (CC)

14. What 2 organizations designate specifications for GMAW wires?
Puddle fluidity
Insufficient current to melt the wire off cleanly
SMAW - GTAW
AWS and CSA

15. What does the term GMAW identify?
Pressure vessels and the piping industry
National Electrical Manufactures Association
To prevent leakage - Carbon Dioxide (CO2)
Gas metal arc welding

16. What is a typical flow rate of CO2 for short circuit transfer?
These terms are quite restrictive and often technically incorrect
To limit the short circuiting current so that spatter is reduced
5.8 to 12.5 L/min
Cause flaking - which can clog the liner and contact tube

17. What current and polarity is generally used with GMAW?
Voltage is the force that overcomes resistance to allow amperage flow
DCEP (Direct Current Electrode Positive) Reverse Polarity
Controls the rate of flow of a shielding gas to the gun nozzle
To limit the short circuiting current so that spatter is reduced

18. List 3 wire drive systems and give a short description of each
Guns
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
Reducing the gas source pressure to a constant working pressure
AWS and CSA

19. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Wire feed speed
Reducing the gas source pressure to a constant working pressure
Cause flaking - which can clog the liner and contact tube
85%

20. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
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Wire feed speed
Reducing the gas source pressure to a constant working pressure
Speed of the feed motor and - starting / stopping electrode feed

21. What is the key advantage of short circuiting transfer?
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
Minimum distortion due to low heat input
Cause flaking - which can clog the liner and contact tube
5.8 to 12.5 L/min

22. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
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Short- circuiting transfer - Globular transfer - Spray transfer
(DCEP) Direct Current Electrode Positive or Reverse polarity
Gives arc voltage values to the control system of the feeder

23. What is the required arc voltage used for short circuit transfer?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
12 to 22 arc volts
Shielding the molten weld metal from atmospheric contamination
Welding process that joins metals by heating them with an electric arc

24. What is the recommended electrode stick- out for .035 solid wire?
National Electrical Manufactures Association
1/4 inch to 1/2 inch
SMAW - GTAW
Aluminum wire

25. Why is the term GMAW preferred over MIG or MAG?
85%
Spatter problems and poor weld appearance
These terms are quite restrictive and often technically incorrect
Higher 26 to 35 arc volts

26. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Minutes of elapsed time continually run (out of 10 minutes)
Generally not as accurate
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
National Electrical Manufactures Association

27. What is a solenoid valve and what actuates it?
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
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Generally not as accurate

28. What power sources are used with the GMAW Process?
Gives arc voltage values to the control system of the feeder
Duty cycle
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Motor driven generators - Transformer rectifiers - and Inverter designs

29. What is another term for electrode holders for GMAW?
Guns
Wire feeds smoothly (yet will slip should a problem occur in the gun)
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

30. How many times per second does short circuiting take place?
(DCEP) Direct Current Electrode Positive or Reverse polarity
15 feet (4.5 meters)
To prevent leakage - Carbon Dioxide (CO2)
20 to 200 times per second

31. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
Minutes of elapsed time continually run (out of 10 minutes)
National Electrical Manufactures Association
Constant current (CC)

32. What is an advantage of pulsed arc transfer with GMAW?
V groove or U groove
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Welding process that joins metals by heating them with an electric arc
Cause flaking - which can clog the liner and contact tube

33. What does the abbreviation NEMA stand for?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
National Electrical Manufactures Association
Gives arc voltage values to the control system of the feeder
The Arc voltage

34. List several industries that would use GMAW
15 feet (4.5 meters)
Dry ice can form within the flow control openings and cause blockage of shielding gas
SMAW - GTAW
Pressure vessels and the piping industry

35. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
20 to 200 times per second
Welding process that joins metals by heating them with an electric arc
When the filler wire is in direct contract with the base metal

36. What is the maximum distance that hard wire can be successfully pushed?
3
Higher 26 to 35 arc volts
15 feet (4.5 meters)
(DCEP) Direct Current Electrode Positive or Reverse polarity

37. What 2 controls are found on a GMAW set- up?
Motor driven generators - Transformer rectifiers - and Inverter designs
Wire feed speed - Voltage control
(DCEP) Direct Current Electrode Positive or Reverse polarity
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

38. What does a flowmeter do and what does it measure?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Controls the rate of flow of a shielding gas to the gun nozzle
1/4 inch to 1/2 inch
5.8 to 12.5 L/min

39. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
Minimum distortion due to low heat input
AWS and CSA
Constant current (CC)

40. What is the purpose of a regulator and what does it indicate on its gauges?
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
Puddle fluidity
Reducing the gas source pressure to a constant working pressure
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

41. 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
Constant voltage (CV)
Cause flaking - which can clog the liner and contact tube

42. When is the metal transferred with short circuit transfer?
When the filler wire is in direct contract with the base metal
Reducing the gas source pressure to a constant working pressure
3
Welding process that joins metals by heating them with an electric arc

43. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Controls the rate of flow of a shielding gas to the gun nozzle
Duty cycle
...
The resistace to electrical current flow increases with it. Causing the electrode to heat

44. What controls amperage when using GMAW?
Flux cored wires
To prevent leakage - Carbon Dioxide (CO2)
Wire feed speed
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

45. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Gives arc voltage values to the control system of the feeder
Penetration and burn - off rate of the electrode
The Arc voltage

46. Why is globular transfer generally avoided with GMAW?
To prevent leakage - Carbon Dioxide (CO2)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Spatter problems and poor weld appearance
Puddle fluidity

47. Give a brief description of the GMAW process
12 to 22 arc volts
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Puddle fluidity
Welding process that joins metals by heating them with an electric arc

48. What does voltage do in an electrical circuit?
Higher 26 to 35 arc volts
The time rate of response for the current rise and fall
Voltage is the force that overcomes resistance to allow amperage flow
15 feet (4.5 meters)

49. What are the 2 types of wire feeders available?
Gives arc voltage values to the control system of the feeder
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Constant- speed wire feeders and Voltage- sennsing wire feeders
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

50. Give a description of 'pinch effect'
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
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun