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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 purpose of the shielding gas used in GMAW?
Speed of the feed motor and - starting / stopping electrode feed
Penetration and burn - off rate of the electrode
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

2. What processes are constant current (CC) power sources designed to be used with?
The negative side of a welding unit
SMAW - GTAW
National Electrical Manufactures Association
Motor driven generators - Transformer rectifiers - and Inverter designs

3. What is another term for electrode holders for GMAW?
Wire feed speed
Guns
Flux cored wires
The resistace to electrical current flow increases with it. Causing the electrode to heat

4. What does inductance control?
To limit the short circuiting current so that spatter is reduced
Gives arc voltage values to the control system of the feeder
By there current carrying capacity
The time rate of response for the current rise and fall

5. What does voltage do in an electrical circuit?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Voltage is the force that overcomes resistance to allow amperage flow
National Electrical Manufactures Association
Reducing the gas source pressure to a constant working pressure

6. What output on the welding machine is used to rate the duty cycle?
Pressure vessels and the piping industry
Minutes of elapsed time continually run (out of 10 minutes)
Constant- speed wire feeders and Voltage- sennsing wire feeders
Motor driven generators - Transformer rectifiers - and Inverter designs

7. What is the maximum distance that hard wire can be successfully pushed?
15 feet (4.5 meters)
Pressure - The rate of flow of a shielding gas
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Speed of the feed motor and - starting / stopping electrode feed

8. What type of power source is used with a constant speed wire feeder?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Gas metal arc welding
Constant voltage (CV)
Flux cored wires

9. What happens when the electrode extension is increased?
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
Motor driven generators - Transformer rectifiers - and Inverter designs
Pressure - The rate of flow of a shielding gas

10. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
Generally not as accurate
Constant current (CC)
Aluminum wire

11. Why is a fiber washer required and what cylinder gas requires it?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
The Arc voltage
To prevent leakage - Carbon Dioxide (CO2)
15 feet (4.5 meters)

12. What is the recommended electrode stick- out for .035 solid wire?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Spatter problems and poor weld appearance
1/4 inch to 1/2 inch
Puddle fluidity

13. What current and polarity is generally used with GMAW?
Controls the rate of flow of a shielding gas to the gun nozzle
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
DCEP (Direct Current Electrode Positive) Reverse Polarity
Minutes of elapsed time continually run (out of 10 minutes)

14. What is the key advantage of short circuiting transfer?
Minutes of elapsed time continually run (out of 10 minutes)
Minimum distortion due to low heat input
Speed of the feed motor and - starting / stopping electrode feed
Insufficient current to melt the wire off cleanly

15. What would be an indication that the drive roll pressure is adjusted correctly?
Gives arc voltage values to the control system of the feeder
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Aluminum wire
5.8 to 12.5 L/min

16. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Minutes of elapsed time continually run (out of 10 minutes)
85%
12 to 22 arc volts
Generally not as accurate

17. When is the metal transferred with short circuit transfer?
1/4 inch to 1/2 inch
Cause flaking - which can clog the liner and contact tube
3
When the filler wire is in direct contract with the base metal

18. What is the purpose of a regulator and what does it indicate on its gauges?
Wire feed speed - Voltage control
Reducing the gas source pressure to a constant working pressure
Spatter problems and poor weld appearance
Pressure - The rate of flow of a shielding gas

19. What controls the wire speed on a voltage sensing wire feeder?
12 to 22 arc volts
The Arc voltage
Constant- speed wire feeders and Voltage- sennsing wire feeders
Flux cored wires

20. What controls amperage when using GMAW?
Wire feed speed
12 to 22 arc volts
Puddle fluidity
To limit the short circuiting current so that spatter is reduced

21. How are GMAW guns rated?
By there current carrying capacity
Generally not as accurate
If you dont know this check your phone
Pressure - The rate of flow of a shielding gas

22. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Shielding the molten weld metal from atmospheric contamination
Welding process that joins metals by heating them with an electric arc
National Electrical Manufactures Association
3

23. 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
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

24. What 2 controls are found on a GMAW set- up?
Wire feed speed - Voltage control
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
Insufficient current to melt the wire off cleanly
Spatter problems and poor weld appearance

25. Why is a line heater required when using GMAW?
3
DCEP (Direct Current Electrode Positive) Reverse Polarity
Pressure - The rate of flow of a shielding gas
Dry ice can form within the flow control openings and cause blockage of shielding gas

26. What does the abbreviation NEMA stand for?
Controls the rate of flow of a shielding gas to the gun nozzle
If you dont know this check your phone
National Electrical Manufactures Association
V groove or U groove

27. List several industries that would use GMAW
1/4 inch to 1/2 inch
(DCEP) Direct Current Electrode Positive or Reverse polarity
Pressure vessels and the piping industry
Speed of the feed motor and - starting / stopping electrode feed

28. A pull type drive system is usually used on what type of material?
Minutes of elapsed time continually run (out of 10 minutes)
Pressure - The rate of flow of a shielding gas
Aluminum wire
Gas metal arc welding

29. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
85%
Cause flaking - which can clog the liner and contact tube

30. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
If you dont know this check your phone
By there current carrying capacity
Higher 26 to 35 arc volts

31. What does a flowmeter do and what does it measure?
Controls the rate of flow of a shielding gas to the gun nozzle
Voltage is the force that overcomes resistance to allow amperage flow
By there current carrying capacity
15 feet (4.5 meters)

32. Why is the term GMAW preferred over MIG or MAG?
Gas metal arc welding
These terms are quite restrictive and often technically incorrect
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
To prevent leakage - Carbon Dioxide (CO2)

33. What is an advantage of pulsed arc transfer with GMAW?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Constant- speed wire feeders and Voltage- sennsing wire feeders
Penetration and burn - off rate of the electrode

34. 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
Minutes of elapsed time continually run (out of 10 minutes)
Aluminum wire
SMAW - GTAW

35. What are the 2 types of wire feeders available?
Motor driven generators - Transformer rectifiers - and Inverter designs
5.8 to 12.5 L/min
Short- circuiting transfer - Globular transfer - Spray transfer
Constant- speed wire feeders and Voltage- sennsing wire feeders

36. Regulators control_____________ flowmeters SHOW____________.
Pressure - The rate of flow of a shielding gas
National Electrical Manufactures Association
Welding process that joins metals by heating them with an electric arc
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

37. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
Motor driven generators - Transformer rectifiers - and Inverter designs
To prevent leakage - Carbon Dioxide (CO2)
Pressure vessels and the piping industry

38. What is the main purpose of 'slope'?
Guns
Pressure - The rate of flow of a shielding gas
By there current carrying capacity
To limit the short circuiting current so that spatter is reduced

39. What does the wire feeder control?
1/4 inch to 1/2 inch
If you dont know this check your phone
5.8 to 12.5 L/min
Speed of the feed motor and - starting / stopping electrode feed

40. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Wire feed speed - Voltage control
Welding process that joins metals by heating them with an electric arc
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Cause flaking - which can clog the liner and contact tube

41. 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
Gives arc voltage values to the control system of the feeder
Gas metal arc welding
Guns

42. Draw a typical volt amp curve for a machine that is designed for GMAW
...
If you dont know this check your phone
The Arc voltage
To prevent leakage - Carbon Dioxide (CO2)

43. What effect does increasing and decreasing the inductance have on the weld?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
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
Gives arc voltage values to the control system of the feeder

44. What is the required arc voltage used for short circuit transfer?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Wire feeds smoothly (yet will slip should a problem occur in the gun)
12 to 22 arc volts
SMAW - GTAW

45. List the factors that determine the mode of metal transfer
Welding process that joins metals by heating them with an electric arc
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Higher 26 to 35 arc volts
Constant current (CC)

46. What type of power source is commonly used with a voltage sensing wire feeder?
Flux cored wires
Constant current (CC)
DCEP (Direct Current Electrode Positive) Reverse Polarity
Minimum distortion due to low heat input

47. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Pressure vessels and the piping industry
...
Wire feed speed
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

48. Give a description of 'pinch effect'
Welding process that joins metals by heating them with an electric arc
Guns
Voltage is the force that overcomes resistance to allow amperage flow
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

49. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
When the filler wire is in direct contract with the base metal
Duty cycle
Constant- speed wire feeders and Voltage- sennsing wire feeders

50. What is a typical flow rate of CO2 for short circuit transfer?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
V groove or U groove
5.8 to 12.5 L/min
To prevent leakage - Carbon Dioxide (CO2)