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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?
Wire feed speed
85%
Penetration and burn - off rate of the electrode
Pressure vessels and the piping industry

2. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Guns
Dry ice can form within the flow control openings and cause blockage of shielding gas
85%
DCEP (Direct Current Electrode Positive) Reverse Polarity

3. What is another term for electrode holders for GMAW?
Guns
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
3

4. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
Gives arc voltage values to the control system of the feeder
5.8 to 12.5 L/min
AWS and CSA

5. What 2 controls are found on a GMAW set- up?
Wire feed speed - Voltage control
Gives arc voltage values to the control system of the 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

6. List the basic equipment requirements for the GMAW process
Voltage is the force that overcomes resistance to allow amperage flow
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
AWS and CSA
5.8 to 12.5 L/min

7. What is a typical flow rate of CO2 for short circuit transfer?
National Electrical Manufactures Association
5.8 to 12.5 L/min
1/4 inch to 1/2 inch
To prevent drawing of liquid CO2 (Carbon Dioxide)

8. Give a brief description of the GMAW process
5.8 to 12.5 L/min
Minimum distortion due to low heat input
Duty cycle
Welding process that joins metals by heating them with an electric arc

9. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Pressure - The rate of flow of a shielding gas
DCEP (Direct Current Electrode Positive) Reverse Polarity

10. What is the main purpose of 'slope'?
5.8 to 12.5 L/min
National Electrical Manufactures Association
To limit the short circuiting current so that spatter is reduced
Gas metal arc welding

11. List 3 wire drive systems and give a short description of each
20 to 200 times per second
Reducing the gas source pressure to a constant working pressure
...
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. What type of power source is commonly used with a voltage sensing wire feeder?
SMAW - GTAW
Generally not as accurate
Constant current (CC)
Penetration and burn - off rate of the electrode

13. What processes are constant current (CC) power sources designed to be used with?
Constant voltage (CV)
SMAW - GTAW
Wire feed speed
To prevent leakage - Carbon Dioxide (CO2)

14. What is the recommended electrode stick- out for .035 solid wire?
Spatter problems and poor weld appearance
Reducing the gas source pressure to a constant working pressure
1/4 inch to 1/2 inch
3

15. Draw a typical volt amp curve for a machine that is designed for GMAW
AWS and CSA
If you dont know this check your phone
Aluminum wire
The Arc voltage

16. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Constant- speed wire feeders and Voltage- sennsing wire feeders
If you dont know this check your phone
Duty cycle
If you dont know this check your phone

17. What is the effect of too much slope?
Minutes of elapsed time continually run (out of 10 minutes)
The time rate of response for the current rise and fall
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Insufficient current to melt the wire off cleanly

18. What type of power source is used with a constant speed wire feeder?
85%
The Arc voltage
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Constant voltage (CV)

19. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
SMAW - GTAW
Wire feed speed - Voltage control
Puddle fluidity

20. List 3 forms compressed gases may be supplied for welding
85%
Pressure vessels and the piping industry
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
To limit the short circuiting current so that spatter is reduced

21. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
To prevent drawing of liquid CO2 (Carbon Dioxide)
Guns
85%

22. What is a solenoid valve and what actuates it?
The Arc voltage
Pressure - The rate of flow of a 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

23. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Cause flaking - which can clog the liner and contact tube
Duty cycle
If you dont know this check your phone

24. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
When the filler wire is in direct contract with the base metal
Generally not as accurate
20 to 200 times per second

25. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Duty cycle
Higher 26 to 35 arc volts
1/4 inch to 1/2 inch

26. What is the purpose of the shielding gas used in GMAW?
Speed of the feed motor and - starting / stopping electrode feed
Shielding the molten weld metal from atmospheric contamination
Reducing the gas source pressure to a constant working pressure
Pressure vessels and the piping industry

27. When is the metal transferred with short circuit transfer?
When the filler wire is in direct contract with the base metal
Guns
3
Wire feeds smoothly (yet will slip should a problem occur in the gun)

28. List several industries that would use GMAW
Constant current (CC)
Guns
Pressure vessels and the piping industry
Generally not as accurate

29. 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
Constant voltage (CV)
The Arc voltage
Flux cored wires

30. How many times per second does short circuiting take place?
20 to 200 times per second
Welding process that joins metals by heating them with an electric arc
...
Spatter problems and poor weld appearance

31. What power sources are used with the GMAW Process?
Welding process that joins metals by heating them with an electric arc
Motor driven generators - Transformer rectifiers - and Inverter designs
The resistace to electrical current flow increases with it. Causing the electrode to heat
Cause flaking - which can clog the liner and contact tube

32. What does voltage do in an electrical circuit?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Voltage is the force that overcomes resistance to allow amperage flow
The Arc voltage
15 feet (4.5 meters)

33. Why is globular transfer generally avoided with GMAW?
Gives arc voltage values to the control system of the feeder
Welding process that joins metals by heating them with an electric arc
The time rate of response for the current rise and fall
Spatter problems and poor weld appearance

34. What is an advantage of pulsed arc transfer with GMAW?
V groove or U groove
Gives arc voltage values to the control system of the feeder
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

35. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Aluminum wire
Constant- speed wire feeders and Voltage- sennsing wire feeders
Cause flaking - which can clog the liner and contact tube
V groove or U groove

36. What does inductance control?
The negative side of a welding unit
The time rate of response for the current rise and fall
To prevent drawing of liquid CO2 (Carbon Dioxide)
Higher 26 to 35 arc volts

37. What 2 organizations designate specifications for GMAW wires?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Insufficient current to melt the wire off cleanly
AWS and CSA
These terms are quite restrictive and often technically incorrect

38. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
The negative side of a welding unit
These terms are quite restrictive and often technically incorrect
Reducing the gas source pressure to a constant working pressure

39. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Pressure - The rate of flow of a shielding gas
85%
Aluminum wire

40. What output on the welding machine is used to rate the duty cycle?
The time rate of response for the current rise and fall
Minutes of elapsed time continually run (out of 10 minutes)
Wire feed speed - Voltage control
Puddle fluidity

41. What does a flowmeter do and what does it measure?
When the filler wire is in direct contract with the base metal
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Controls the rate of flow of a shielding gas to the gun nozzle
The Arc voltage

42. What is the maximum distance that hard wire can be successfully pushed?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
To limit the short circuiting current so that spatter is reduced
15 feet (4.5 meters)
Spatter problems and poor weld appearance

43. What is the preferred drive roll design for solid wires?
5.8 to 12.5 L/min
V groove or U groove
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Wire feed speed

44. 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
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Puddle fluidity
Voltage is the force that overcomes resistance to allow amperage flow

45. 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
The negative side of a welding unit
To limit the short circuiting current so that spatter is reduced

46. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
If you dont know this check your phone
Wire feed speed
15 feet (4.5 meters)
...

47. Why must CO2 cylinders be used in the vertical position?
AWS and CSA
3
Penetration and burn - off rate of the electrode
To prevent drawing of liquid CO2 (Carbon Dioxide)

48. What is the required arc voltage used for short circuit transfer?
Constant voltage (CV)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Minimum distortion due to low heat input
12 to 22 arc volts

49. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
1/4 inch to 1/2 inch
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
To limit the short circuiting current so that spatter is reduced

50. Why is the term GMAW preferred over MIG or MAG?
Wire feed speed
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
85%
These terms are quite restrictive and often technically incorrect