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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 controls amperage when using GMAW?
Constant current (CC)
These terms are quite restrictive and often technically incorrect
DCEP (Direct Current Electrode Positive) Reverse Polarity
Wire feed speed

2. Why must CO2 cylinders be used in the vertical position?
15 feet (4.5 meters)
Motor driven generators - Transformer rectifiers - and Inverter designs
To prevent drawing of liquid CO2 (Carbon Dioxide)
If you dont know this check your phone

3. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
Controls the rate of flow of a shielding gas to the gun nozzle
Cause flaking - which can clog the liner and contact tube
Guns

4. List several industries that would use GMAW
Pressure vessels and the piping industry
V groove or U groove
3
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

5. Why is globular transfer generally avoided with GMAW?
Guns
Spatter problems and poor weld appearance
Constant- speed wire feeders and Voltage- sennsing wire feeders
Minimum distortion due to low heat input

6. With straight polarity where is 2/3 of the arc energy?
Short- circuiting transfer - Globular transfer - Spray transfer
Welding process that joins metals by heating them with an electric arc
The negative side of a welding unit
V groove or U groove

7. 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
Minutes of elapsed time continually run (out of 10 minutes)
V groove or U groove
Gas metal arc welding

8. 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
Higher 26 to 35 arc volts
Welding process that joins metals by heating them with an electric arc
Aluminum wire

9. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Wire feed speed - Voltage control
Gives arc voltage values to the control system of the feeder
Penetration and burn - off rate of the electrode

10. What 2 controls are found on a GMAW set- up?
Wire feed speed - Voltage control
3
The resistace to electrical current flow increases with it. Causing the electrode to heat
Controls the rate of flow of a shielding gas to the gun nozzle

11. List the basic equipment requirements for the GMAW process
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
AWS and CSA
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

12. Why is the term GMAW preferred over MIG or MAG?
Voltage is the force that overcomes resistance to allow amperage flow
Minimum distortion due to low heat input
Aluminum wire
These terms are quite restrictive and often technically incorrect

13. Why is a fiber washer required and what cylinder gas requires it?
National Electrical Manufactures Association
To prevent leakage - Carbon Dioxide (CO2)
The time rate of response for the current rise and fall
Dry ice can form within the flow control openings and cause blockage of shielding gas

14. What wire are knurled drive rolls most commonly used on?
...
Wire feed speed
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Flux cored wires

15. What is the effect of too much slope?
The time rate of response for the current rise and fall
Penetration and burn - off rate of the electrode
Insufficient current to melt the wire off cleanly
The resistace to electrical current flow increases with it. Causing the electrode to heat

16. What is the required arc voltage used for short circuit transfer?
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
12 to 22 arc volts
Speed of the feed motor and - starting / stopping electrode feed

17. What is the recommended electrode stick- out for .035 solid wire?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Duty cycle
1/4 inch to 1/2 inch
Guns

18. What does the wire feeder control?
Pressure - The rate of flow of a shielding gas
Speed of the feed motor and - starting / stopping electrode feed
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Constant- speed wire feeders and Voltage- sennsing wire feeders

19. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
15 feet (4.5 meters)
Speed of the feed motor and - starting / stopping electrode feed
Reducing the gas source pressure to a constant working pressure

20. Give a description of 'pinch effect'
Flux cored wires
Constant- speed wire feeders and Voltage- sennsing wire feeders
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
If you dont know this check your phone

21. What happens when the electrode extension is increased?
Speed of the feed motor and - starting / stopping electrode feed
AWS and CSA
The resistace to electrical current flow increases with it. Causing the electrode to heat
If you dont know this check your phone

22. What is the preferred drive roll design for solid wires?
Wire feed speed - Voltage control
Penetration and burn - off rate of the electrode
V groove or U groove
Minimum distortion due to low heat input

23. In the GMAW process what does voltage control?
V groove or U groove
Puddle fluidity
Higher 26 to 35 arc volts
Reducing the gas source pressure to a constant working pressure

24. What type of power source is commonly used with a voltage sensing wire feeder?
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
Constant current (CC)
Constant- speed wire feeders and Voltage- sennsing wire feeders
National Electrical Manufactures Association

25. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Cause flaking - which can clog the liner and contact tube
If you dont know this check your phone
Generally not as accurate
85%

26. What does a flowmeter do and what does it measure?
Controls the rate of flow of a shielding gas to the gun nozzle
Higher 26 to 35 arc volts
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Motor driven generators - Transformer rectifiers - and Inverter designs

27. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
(DCEP) Direct Current Electrode Positive or Reverse polarity
To prevent leakage - Carbon Dioxide (CO2)
By there current carrying capacity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

28. 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
SMAW - GTAW
Welding process that joins metals by heating them with an electric arc

29. What is the main purpose of 'slope'?
To prevent leakage - Carbon Dioxide (CO2)
1/4 inch to 1/2 inch
To limit the short circuiting current so that spatter is reduced
Dry ice can form within the flow control openings and cause blockage of shielding gas

30. List the factors that determine the mode of metal transfer
AWS and CSA
5.8 to 12.5 L/min
Higher 26 to 35 arc volts
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

31. How are GMAW guns rated?
12 to 22 arc volts
By there current carrying capacity
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Wire feed speed

32. When is the metal transferred with 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
When the filler wire is in direct contract with the base metal
20 to 200 times per second

33. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Puddle fluidity
Cause flaking - which can clog the liner and contact tube
If you dont know this check your phone
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

34. List 3 forms compressed gases may be supplied for welding
Controls the rate of flow of a shielding gas to the gun nozzle
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Higher 26 to 35 arc volts
20 to 200 times per second

35. Why is a line heater required when using GMAW?
Gives arc voltage values to the control system of the feeder
Insufficient current to melt the wire off cleanly
If you dont know this check your phone
Dry ice can form within the flow control openings and cause blockage of shielding gas

36. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
If you dont know this check your phone
The resistace to electrical current flow increases with it. Causing the electrode to heat
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

37. What power sources are used with the GMAW Process?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Welding process that joins metals by heating them with an electric arc
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Motor driven generators - Transformer rectifiers - and Inverter designs

38. What processes are constant current (CC) power sources designed to be used with?
15 feet (4.5 meters)
Duty cycle
Gives arc voltage values to the control system of the feeder
SMAW - GTAW

39. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
15 feet (4.5 meters)
The negative side of a welding unit
Penetration and burn - off rate of the electrode

40. What are the 2 types of wire feeders available?
Dry ice can form within the flow control openings and cause blockage of shielding gas
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
Constant- speed wire feeders and Voltage- sennsing wire feeders

41. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
The time rate of response for the current rise and fall
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

42. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
Minutes of elapsed time continually run (out of 10 minutes)
Gas metal arc welding
By there current carrying capacity

43. What is the maximum distance that hard wire can be successfully pushed?
Speed of the feed motor and - starting / stopping electrode feed
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
15 feet (4.5 meters)
Constant current (CC)

44. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
...
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
AWS and CSA

45. What is the purpose of a regulator and what does it indicate on its gauges?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Reducing the gas source pressure to a constant working pressure
DCEP (Direct Current Electrode Positive) Reverse Polarity
By there current carrying capacity

46. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
Dry ice can form within the flow control openings and cause blockage of shielding gas
DCEP (Direct Current Electrode Positive) Reverse Polarity
...

47. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
Flux cored wires
Shielding the molten weld metal from atmospheric contamination
Guns

48. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
If you dont know this check your phone
Wire feed speed
V groove or U groove

49. A 10 minute cycle of welding time vs cooling time a given machine can handle.
To prevent leakage - Carbon Dioxide (CO2)
DCEP (Direct Current Electrode Positive) Reverse Polarity
Duty cycle
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

50. Regulators control_____________ flowmeters SHOW____________.
Minimum distortion due to low heat input
Pressure - The rate of flow of a shielding gas
Shielding the molten weld metal from atmospheric contamination
15 feet (4.5 meters)