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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 current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
The time rate of response for the current rise and fall
(DCEP) Direct Current Electrode Positive or Reverse polarity
Voltage is the force that overcomes resistance to allow amperage flow

2. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Welding process that joins metals by heating them with an electric arc
When the filler wire is in direct contract with the base metal
(DCEP) Direct Current Electrode Positive or Reverse polarity
Cause flaking - which can clog the liner and contact tube

3. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Generally not as accurate
Gives arc voltage values to the control system of the feeder
85%

4. What does the term GMAW identify?
Cause flaking - which can clog the liner and contact tube
Constant current (CC)
Gas metal arc welding
To prevent drawing of liquid CO2 (Carbon Dioxide)

5. What is the preferred drive roll design for solid wires?
Wire feed speed - Voltage control
Pressure vessels and the piping industry
V groove or U groove
Dry ice can form within the flow control openings and cause blockage of shielding gas

6. What is the purpose of a regulator and what does it indicate on its gauges?
Reducing the gas source pressure to a constant working pressure
Minimum distortion due to low heat input
The negative side of a welding unit
SMAW - GTAW

7. What are the 2 types of wire feeders available?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
15 feet (4.5 meters)
Constant- speed wire feeders and Voltage- sennsing wire feeders
Flux cored wires

8. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Puddle fluidity
3
V groove or U groove

9. What controls amperage when using GMAW?
1/4 inch to 1/2 inch
AWS and CSA
20 to 200 times per second
Wire feed speed

10. What does inductance control?
20 to 200 times per second
The time rate of response for the current rise and fall
Short- circuiting transfer - Globular transfer - Spray transfer
Cause flaking - which can clog the liner and contact tube

11. What wire are knurled drive rolls most commonly used on?
Flux cored wires
By there current carrying capacity
To limit the short circuiting current so that spatter is reduced
85%

12. What type of power source is used with a constant speed wire feeder?
Penetration and burn - off rate of the electrode
Insufficient current to melt the wire off cleanly
Constant voltage (CV)
Wire feeds smoothly (yet will slip should a problem occur in the gun)

13. What 2 controls are found on a GMAW set- up?
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
Penetration and burn - off rate of the electrode
Wire feed speed - Voltage control
Voltage is the force that overcomes resistance to allow amperage flow

14. What output on the welding machine is used to rate the duty cycle?
Gives arc voltage values to the control system of the feeder
Minutes of elapsed time continually run (out of 10 minutes)
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

15. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
When the filler wire is in direct contract with the base metal
85%
Guns
Constant voltage (CV)

16. 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
V groove or U groove
When the filler wire is in direct contract with the base metal
Minutes of elapsed time continually run (out of 10 minutes)

17. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
When the filler wire is in direct contract with the base metal
5.8 to 12.5 L/min
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

18. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
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V groove or U groove
National Electrical Manufactures Association
Constant- speed wire feeders and Voltage- sennsing wire feeders

19. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
Shielding the molten weld metal from atmospheric contamination
Penetration and burn - off rate of the electrode
Controls the rate of flow of a shielding gas to the gun nozzle

20. What would be an indication that the drive roll pressure is adjusted correctly?
DCEP (Direct Current Electrode Positive) Reverse Polarity
To prevent leakage - Carbon Dioxide (CO2)
Wire feeds smoothly (yet will slip should a problem occur in the gun)
1/4 inch to 1/2 inch

21. What does the abbreviation NEMA stand for?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
National Electrical Manufactures Association
Constant current (CC)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

22. When is the metal transferred with short circuit transfer?
Wire feed speed
Insufficient current to melt the wire off cleanly
Speed of the feed motor and - starting / stopping electrode feed
When the filler wire is in direct contract with the base metal

23. List the factors that determine the mode of metal transfer
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
The negative side of a welding unit
85%

24. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
The Arc voltage
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
1/4 inch to 1/2 inch

25. List 3 forms compressed gases may be supplied for welding
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Guns
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Minimum distortion due to low heat input

26. List 3 wire drive systems and give a short description of each
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
20 to 200 times per second
If you dont know this check your phone

27. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
Reducing the gas source pressure to a constant working pressure
If you dont know this check your phone
Penetration and burn - off rate of the electrode

28. What effect does increasing and decreasing the inductance have on the weld?
Puddle fluidity
AWS and CSA
Constant- speed wire feeders and Voltage- sennsing wire feeders
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

29. What does voltage do in an electrical circuit?
The resistace to electrical current flow increases with it. Causing the electrode to heat
DCEP (Direct Current Electrode Positive) Reverse Polarity
Voltage is the force that overcomes resistance to allow amperage flow
Minimum distortion due to low heat input

30. What does a flowmeter do and what does it measure?
Controls the rate of flow of a shielding gas to the gun nozzle
The resistace to electrical current flow increases with it. Causing the electrode to heat
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
These terms are quite restrictive and often technically incorrect

31. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Gives arc voltage values to the control system of the feeder
1/4 inch to 1/2 inch
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

32. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
15 feet (4.5 meters)
Voltage is the force that overcomes resistance to allow amperage flow
Cause flaking - which can clog the liner and contact tube
Speed of the feed motor and - starting / stopping electrode feed

33. A pull type drive system is usually used on what type of material?
Flux cored wires
When the filler wire is in direct contract with the base metal
Aluminum wire
Insufficient current to melt the wire off cleanly

34. What is the maximum distance that hard wire can be successfully pushed?
Puddle fluidity
15 feet (4.5 meters)
National Electrical Manufactures Association
Minimum distortion due to low heat input

35. What type of power source is commonly used with a voltage sensing wire feeder?
Constant current (CC)
3
If you dont know this check your phone
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

36. In the GMAW process what does voltage control?
15 feet (4.5 meters)
Puddle fluidity
The negative side of a welding unit
Pressure vessels and the piping industry

37. What is the purpose of the shielding gas used in GMAW?
Aluminum wire
Higher 26 to 35 arc volts
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Shielding the molten weld metal from atmospheric contamination

38. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
Minimum distortion due to low heat input
Controls the rate of flow of a shielding gas to the gun nozzle
20 to 200 times per second

39. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Insufficient current to melt the wire off cleanly
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
85%

40. List several industries that would use GMAW
(DCEP) Direct Current Electrode Positive or Reverse polarity
Cause flaking - which can clog the liner and contact tube
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Pressure vessels and the piping industry

41. What is the key advantage of short circuiting transfer?
Spatter problems and poor weld appearance
Flux cored wires
Minimum distortion due to low heat input
Pressure - The rate of flow of a shielding gas

42. Draw a typical volt amp curve for a machine that is designed for GMAW
National Electrical Manufactures Association
15 feet (4.5 meters)
Guns
If you dont know this check your phone

43. Why is the term GMAW preferred over MIG or MAG?
Spatter problems and poor weld appearance
Voltage is the force that overcomes resistance to allow amperage flow
These terms are quite restrictive and often technically incorrect
Constant- speed wire feeders and Voltage- sennsing wire feeders

44. What is another term for electrode holders for GMAW?
Guns
Controls the rate of flow of a shielding gas to the gun nozzle
Constant- speed wire feeders and Voltage- sennsing wire feeders
1/4 inch to 1/2 inch

45. Regulators control_____________ flowmeters SHOW____________.
Guns
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Pressure - The rate of flow of a shielding gas
Voltage is the force that overcomes resistance to allow amperage flow

46. Why is a line heater required when using GMAW?
5.8 to 12.5 L/min
Gives arc voltage values to the control system of the feeder
Gas metal arc welding
Dry ice can form within the flow control openings and cause blockage of shielding gas

47. How many times per second does short circuiting take place?
Voltage is the force that overcomes resistance to allow amperage flow
20 to 200 times per second
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

48. Why must CO2 cylinders be used in the vertical position?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Penetration and burn - off rate of the electrode
SMAW - GTAW
To prevent drawing of liquid CO2 (Carbon Dioxide)

49. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Voltage is the force that overcomes resistance to allow amperage flow
85%
To prevent drawing of liquid CO2 (Carbon Dioxide)
Higher 26 to 35 arc volts

50. What does the wire feeder control?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
The resistace to electrical current flow increases with it. Causing the electrode to heat
Speed of the feed motor and - starting / stopping electrode feed
The time rate of response for the current rise and fall