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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 an advantage of pulsed arc transfer with GMAW?
Pressure - The rate of flow of a shielding gas
Shielding the molten weld metal from atmospheric contamination
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Wire feeds smoothly (yet will slip should a problem occur in the gun)

2. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
Shielding the molten weld metal from atmospheric contamination
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Voltage is the force that overcomes resistance to allow amperage flow

3. 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
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Constant current (CC)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

4. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Cause flaking - which can clog the liner and contact tube
Minutes of elapsed time continually run (out of 10 minutes)

5. What wire are knurled drive rolls most commonly used on?
Puddle fluidity
Minutes of elapsed time continually run (out of 10 minutes)
Flux cored wires
When the filler wire is in direct contract with the base metal

6. What effect does increasing and decreasing the inductance have on the weld?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Dry ice can form within the flow control openings and cause blockage of shielding gas
Guns
Penetration and burn - off rate of the electrode

7. What output on the welding machine is used to rate the duty cycle?
Minutes of elapsed time continually run (out of 10 minutes)
Reducing the gas source pressure to a constant working pressure
Cause flaking - which can clog the liner and contact tube
Puddle fluidity

8. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Insufficient current to melt the wire off cleanly
The time rate of response for the current rise and fall
85%

9. Why is a line heater required when using GMAW?
Constant voltage (CV)
Gives arc voltage values to the control system of the feeder
Dry ice can form within the flow control openings and cause blockage of shielding gas
V groove or U groove

10. What type of power source is commonly used with a voltage sensing wire feeder?
Higher 26 to 35 arc volts
Constant current (CC)
12 to 22 arc volts
Minimum distortion due to low heat input

11. What is the required arc voltage used for short circuit transfer?
Minimum distortion due to low heat input
12 to 22 arc volts
Motor driven generators - Transformer rectifiers - and Inverter designs
3

12. List the factors that determine the mode of metal transfer
To prevent drawing of liquid CO2 (Carbon Dioxide)
SMAW - GTAW
Wire feed speed
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

13. What controls amperage when using GMAW?
If you dont know this check your phone
Wire feed speed
Penetration and burn - off rate of the electrode
V groove or U groove

14. What is the recommended electrode stick- out for .035 solid wire?
Cause flaking - which can clog the liner and contact tube
If you dont know this check your phone
Wire feed speed
1/4 inch to 1/2 inch

15. What power sources are used with the GMAW Process?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Motor driven generators - Transformer rectifiers - and Inverter designs
Voltage is the force that overcomes resistance to allow amperage flow
5.8 to 12.5 L/min

16. A pull type drive system is usually used on what type of material?
Aluminum wire
To limit the short circuiting current so that spatter is reduced
The time rate of response for the current rise and fall
Speed of the feed motor and - starting / stopping electrode feed

17. 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
The Arc voltage
These terms are quite restrictive and often technically incorrect
Gives arc voltage values to the control system of the feeder

18. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Aluminum wire
Penetration and burn - off rate of the electrode

19. What are the 2 types of wire feeders available?
Welding process that joins metals by heating them with an electric arc
Generally not as accurate
Constant- speed wire feeders and Voltage- sennsing wire feeders
AWS and CSA

20. What does the abbreviation NEMA stand for?
1/4 inch to 1/2 inch
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Controls the rate of flow of a shielding gas to the gun nozzle
National Electrical Manufactures Association

21. 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
Reducing the gas source pressure to a constant working pressure
Duty cycle
Minutes of elapsed time continually run (out of 10 minutes)

22. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
12 to 22 arc volts
SMAW - GTAW
Controls the rate of flow of a shielding gas to the gun nozzle

23. List the basic equipment requirements for the GMAW process
If you dont know this check your phone
Guns
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

24. Why is a fiber washer required and what cylinder gas requires it?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
To prevent leakage - Carbon Dioxide (CO2)
Controls the rate of flow of a shielding gas to the gun nozzle

25. List the three methods of metal transfer with GMAW
To prevent drawing of liquid CO2 (Carbon Dioxide)
National Electrical Manufactures Association
To limit the short circuiting current so that spatter is reduced
Short- circuiting transfer - Globular transfer - Spray transfer

26. What controls the wire speed on a voltage sensing wire feeder?
When the filler wire is in direct contract with the base metal
The Arc voltage
Wire feed speed
Short- circuiting transfer - Globular transfer - Spray transfer

27. Give a brief description of the GMAW process
Reducing the gas source pressure to a constant working pressure
Puddle fluidity
Welding process that joins metals by heating them with an electric arc
Spatter problems and poor weld appearance

28. Regulators control_____________ flowmeters SHOW____________.
Pressure - The rate of flow of a shielding gas
20 to 200 times per second
15 feet (4.5 meters)
The Arc voltage

29. List 3 wire drive systems and give a short description of each
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
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

30. Why is the term GMAW preferred over MIG or MAG?
Pressure vessels and the piping industry
By there current carrying capacity
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
These terms are quite restrictive and often technically incorrect

31. How are GMAW guns rated?
By there current carrying capacity
Constant- speed wire feeders and Voltage- sennsing wire feeders
Short- circuiting transfer - Globular transfer - Spray transfer
Voltage is the force that overcomes resistance to allow amperage flow

32. What is a solenoid valve and what actuates it?
20 to 200 times per second
AWS and CSA
Cause flaking - which can clog the liner and contact tube
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

33. What would be an indication that the drive roll pressure is adjusted correctly?
Speed of the feed motor and - starting / stopping electrode feed
Wire feed speed - Voltage control
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Insufficient current to melt the wire off cleanly

34. Why is globular transfer generally avoided with GMAW?
Insufficient current to melt the wire off cleanly
(DCEP) Direct Current Electrode Positive or Reverse polarity
Spatter problems and poor weld appearance
Minimum distortion due to low heat input

35. List 3 forms compressed gases may be supplied for welding
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Speed of the feed motor and - starting / stopping electrode feed
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Spatter problems and poor weld appearance

36. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
To prevent leakage - Carbon Dioxide (CO2)
Gives arc voltage values to the control system of the feeder
Motor driven generators - Transformer rectifiers - and Inverter designs
Penetration and burn - off rate of the electrode

37. Draw a typical volt amp curve for a machine that is designed for GMAW
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Wire feed speed
If you dont know this check your phone
Pressure - The rate of flow of a shielding gas

38. List several industries that would use GMAW
3
Penetration and burn - off rate of the electrode
The Arc voltage
Pressure vessels and the piping industry

39. With straight polarity where is 2/3 of the arc energy?
National Electrical Manufactures Association
The negative side of a welding unit
Duty cycle
To limit the short circuiting current so that spatter is reduced

40. What 2 controls are found on a GMAW set- up?
...
The Arc voltage
Wire feed speed - Voltage control
Cause flaking - which can clog the liner and contact tube

41. What does voltage do in an electrical circuit?
Speed of the feed motor and - starting / stopping electrode feed
Cause flaking - which can clog the liner and contact tube
Shielding the molten weld metal from atmospheric contamination
Voltage is the force that overcomes resistance to allow amperage flow

42. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
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
Wire feed speed

43. What is the effect of too much slope?
Pressure vessels and the piping industry
Insufficient current to melt the wire off cleanly
SMAW - GTAW
To limit the short circuiting current so that spatter is reduced

44. When is the metal transferred with short circuit transfer?
When the filler wire is in direct contract with the base metal
The time rate of response for the current rise and fall
12 to 22 arc volts
20 to 200 times per second

45. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Generally not as accurate

46. What is the purpose of a regulator and what does it indicate on its gauges?
To prevent leakage - Carbon Dioxide (CO2)
Gives arc voltage values to the control system of the feeder
DCEP (Direct Current Electrode Positive) Reverse Polarity
Reducing the gas source pressure to a constant working pressure

47. What is the preferred drive roll design for solid wires?
National Electrical Manufactures Association
V groove or U groove
Voltage is the force that overcomes resistance to allow amperage flow
Controls the rate of flow of a shielding gas to the gun nozzle

48. What is the key advantage of short circuiting transfer?
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
Minimum distortion due to low heat input
To limit the short circuiting current so that spatter is reduced

49. How many times per second does short circuiting take place?
Cause flaking - which can clog the liner and contact tube
20 to 200 times per second
Wire feed speed
15 feet (4.5 meters)

50. Give a description of 'pinch effect'
Higher 26 to 35 arc volts
Insufficient current to melt the wire off cleanly
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)