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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.
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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 is the required arc voltage used for short circuit transfer?
12 to 22 arc volts
...
3
When the filler wire is in direct contract with the base metal

2. With straight polarity where is 2/3 of the arc energy?
Wire feed speed - Voltage control
The negative side of a welding unit
85%
Speed of the feed motor and - starting / stopping electrode feed

3. How are GMAW guns rated?
AWS and CSA
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
By there current carrying capacity
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

4. What does the term GMAW identify?
5.8 to 12.5 L/min
Shielding the molten weld metal from atmospheric contamination
Spatter problems and poor weld appearance
Gas metal arc welding

5. How many times per second does short circuiting take place?
20 to 200 times per second
By there current carrying capacity
15 feet (4.5 meters)
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

6. In the GMAW process what does voltage control?
AWS and CSA
To prevent leakage - Carbon Dioxide (CO2)
Puddle fluidity
Short- circuiting transfer - Globular transfer - Spray transfer

7. What does a flowmeter do and what does it measure?
Controls the rate of flow of a shielding gas to the gun nozzle
The time rate of response for the current rise and fall
To prevent drawing of liquid CO2 (Carbon Dioxide)
20 to 200 times per second

8. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
The Arc voltage
Voltage is the force that overcomes resistance to allow amperage flow
3
Welding process that joins metals by heating them with an electric arc

9. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Pressure - The rate of flow of a shielding gas
To prevent leakage - Carbon Dioxide (CO2)
(DCEP) Direct Current Electrode Positive or Reverse polarity
Welding process that joins metals by heating them with an electric arc

10. What does inductance control?
Minutes of elapsed time continually run (out of 10 minutes)
Aluminum wire
The time rate of response for the current rise and fall
Constant- speed wire feeders and Voltage- sennsing wire feeders

11. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
If you dont know this check your phone
Wire feed speed - Voltage control
Pressure - The rate of flow of a shielding gas

12. List 3 wire drive systems and give a short description of each
To prevent drawing of liquid CO2 (Carbon Dioxide)
Motor driven generators - Transformer rectifiers - and Inverter designs
Constant current (CC)
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

13. What is an advantage of pulsed arc transfer with GMAW?
SMAW - GTAW
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
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

14. What output on the welding machine is used to rate the duty cycle?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Minutes of elapsed time continually run (out of 10 minutes)
Generally not as accurate
Puddle fluidity

15. List the factors that determine the mode of metal transfer
V groove or U groove
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Higher 26 to 35 arc volts
Duty cycle

16. When is the metal transferred with short circuit transfer?
Guns
When the filler wire is in direct contract with the base metal
Wire feeds smoothly (yet will slip should a problem occur in the gun)
1/4 inch to 1/2 inch

17. What is a typical flow rate of CO2 for short circuit transfer?
The Arc voltage
5.8 to 12.5 L/min
Pressure vessels and the piping industry
Higher 26 to 35 arc volts

18. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Pressure vessels and the piping industry
20 to 200 times per second
Aluminum wire
Generally not as accurate

19. What is the maximum distance that hard wire can be successfully pushed?
Gives arc voltage values to the control system of the feeder
15 feet (4.5 meters)
Pressure - The rate of flow of a shielding gas
Insufficient current to melt the wire off cleanly

20. Draw a typical volt amp curve for a machine that is designed for GMAW
The resistace to electrical current flow increases with it. Causing the electrode to heat
National Electrical Manufactures Association
If you dont know this check your phone
Gives arc voltage values to the control system of the feeder

21. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
...
AWS and CSA
Spatter problems and poor weld appearance
Puddle fluidity

22. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
1/4 inch to 1/2 inch
20 to 200 times per second
If you dont know this check your phone

23. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
To limit the short circuiting current so that spatter is reduced
Penetration and burn - off rate of the electrode

24. What is the preferred drive roll design for solid wires?
V groove or U groove
Speed of the feed motor and - starting / stopping electrode feed
Constant- speed wire feeders and Voltage- sennsing wire feeders
By there current carrying capacity

25. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Speed of the feed motor and - starting / stopping electrode feed
Pressure - The rate of flow of a shielding gas

26. What is the recommended electrode stick- out for .035 solid wire?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
DCEP (Direct Current Electrode Positive) Reverse Polarity
Wire feeds smoothly (yet will slip should a problem occur in the gun)
1/4 inch to 1/2 inch

27. What 2 controls are found on a GMAW set- up?
15 feet (4.5 meters)
Wire feed speed - Voltage control
Aluminum wire
Penetration and burn - off rate of the electrode

28. What would be an indication that the drive roll pressure is adjusted correctly?
Duty cycle
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Puddle fluidity
Cause flaking - which can clog the liner and contact tube

29. Regulators control_____________ flowmeters SHOW____________.
Pressure - The rate of flow of a shielding gas
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
3
National Electrical Manufactures Association

30. What is a solenoid valve and what actuates it?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Constant current (CC)
If you dont know this check your phone
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

31. What wire are knurled drive rolls most commonly used on?
Wire feed speed
Flux cored wires
Cause flaking - which can clog the liner and contact tube
If you dont know this check your phone

32. What does the wire feeder control?
Speed of the feed motor and - starting / stopping electrode feed
Spatter problems and poor weld appearance
Wire feed speed - Voltage control
By there current carrying capacity

33. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Higher 26 to 35 arc volts
Cause flaking - which can clog the liner and contact tube
Welding process that joins metals by heating them with an electric arc
AWS and CSA

34. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Generally not as accurate
Short- circuiting transfer - Globular transfer - Spray transfer
Gives arc voltage values to the control system of the feeder
Insufficient current to melt the wire off cleanly

35. What power sources are used with the GMAW Process?
Gas metal arc welding
20 to 200 times per second
Motor driven generators - Transformer rectifiers - and Inverter designs
The time rate of response for the current rise and fall

36. What is the purpose of the shielding gas used in GMAW?
SMAW - GTAW
85%
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
Shielding the molten weld metal from atmospheric contamination

37. What effect does increasing and decreasing the inductance have on the weld?
Guns
Pressure vessels and the piping industry
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Constant current (CC)

38. What type of power source is used with a constant speed wire feeder?
Shielding the molten weld metal from atmospheric contamination
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Constant voltage (CV)
Pressure - The rate of flow of a shielding gas

39. What is the main purpose of 'slope'?
Pressure vessels and the piping industry
Guns
To limit the short circuiting current so that spatter is reduced
The Arc voltage

40. What does the abbreviation NEMA stand for?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Minutes of elapsed time continually run (out of 10 minutes)
V groove or U groove
National Electrical Manufactures Association

41. Why must CO2 cylinders be used in the vertical position?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
20 to 200 times per second
Short- circuiting transfer - Globular transfer - Spray transfer
To prevent drawing of liquid CO2 (Carbon Dioxide)

42. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
1/4 inch to 1/2 inch
Constant- speed wire feeders and Voltage- sennsing wire feeders
If you dont know this check your phone
15 feet (4.5 meters)

43. What type of power source is commonly used with a voltage sensing wire feeder?
Constant current (CC)
Short- circuiting transfer - Globular transfer - Spray 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
These terms are quite restrictive and often technically incorrect

44. What processes are constant current (CC) power sources designed to be used with?
Gives arc voltage values to the control system of the feeder
SMAW - GTAW
Constant- speed wire feeders and Voltage- sennsing wire feeders
Wire feed speed

45. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
SMAW - GTAW
85%
Insufficient current to melt the wire off cleanly
Constant- speed wire feeders and Voltage- sennsing wire feeders

46. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
SMAW - GTAW
5.8 to 12.5 L/min

47. What are the 2 types of wire feeders available?
Gives arc voltage values to the control system of the feeder
Constant- speed wire feeders and Voltage- sennsing wire feeders
Pressure - The rate of flow of a shielding gas
Wire feed speed

48. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
To prevent leakage - Carbon Dioxide (CO2)
Controls the rate of flow of a shielding gas to the gun nozzle

49. What controls the wire speed on a voltage sensing wire feeder?
Minutes of elapsed time continually run (out of 10 minutes)
Controls the rate of flow of a shielding gas to the gun nozzle
Aluminum wire
The Arc voltage

50. What current and polarity is generally used with GMAW?
These terms are quite restrictive and often technically incorrect
Duty cycle
To limit the short circuiting current so that spatter is reduced
DCEP (Direct Current Electrode Positive) Reverse Polarity