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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 are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Wire feed speed - Voltage control
Gives arc voltage values to the control system of the feeder

2. What does a flowmeter do and what does it measure?
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
20 to 200 times per second

3. How many times per second does short circuiting take place?
Minimum distortion due to low heat input
Constant- speed wire feeders and Voltage- sennsing wire feeders
Wire feed speed
20 to 200 times per second

4. List several industries that would use GMAW
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
20 to 200 times per second
Pressure vessels and the piping industry
Higher 26 to 35 arc volts

5. What is an advantage of pulsed arc transfer with GMAW?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Short- circuiting transfer - Globular transfer - Spray transfer
Shielding the molten weld metal from atmospheric contamination
To limit the short circuiting current so that spatter is reduced

6. What output on the welding machine is used to rate the duty cycle?
Short- circuiting transfer - Globular transfer - Spray transfer
Minutes of elapsed time continually run (out of 10 minutes)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
3

7. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
SMAW - GTAW
...
85%
Puddle fluidity

8. What is the maximum distance that hard wire can be successfully pushed?
Short- circuiting transfer - Globular transfer - Spray transfer
15 feet (4.5 meters)
Dry ice can form within the flow control openings and cause blockage of shielding gas
The negative side of a welding unit

9. What is another term for electrode holders for GMAW?
Speed of the feed motor and - starting / stopping electrode feed
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
1/4 inch to 1/2 inch
Guns

10. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
...
SMAW - GTAW
15 feet (4.5 meters)

11. Why is the term GMAW preferred over MIG or MAG?
The resistace to electrical current flow increases with it. Causing the electrode to heat
12 to 22 arc volts
If you dont know this check your phone
These terms are quite restrictive and often technically incorrect

12. Give a brief description of the GMAW process
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Welding process that joins metals by heating them with an electric arc
Minutes of elapsed time continually run (out of 10 minutes)
The negative side of a welding unit

13. In the GMAW process what does amperage control?
85%
National Electrical Manufactures Association
AWS and CSA
Penetration and burn - off rate of the electrode

14. What is the effect of too much slope?
Short- circuiting transfer - Globular transfer - Spray transfer
Wire feed speed
Insufficient current to melt the wire off cleanly
Pressure - The rate of flow of a shielding gas

15. What does inductance control?
The time rate of response for the current rise and fall
Gas metal arc welding
Wire feed speed - Voltage control
Flux cored wires

16. What 2 controls are found on a GMAW set- up?
Wire feed speed - Voltage control
Generally not as accurate
To limit the short circuiting current so that spatter is reduced
Cause flaking - which can clog the liner and contact tube

17. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
Motor driven generators - Transformer rectifiers - and Inverter designs
Dry ice can form within the flow control openings and cause blockage of shielding gas
Shielding the molten weld metal from atmospheric contamination

18. What does the term GMAW identify?
By there current carrying capacity
Gas metal arc welding
Wire feeds smoothly (yet will slip should a problem occur in the gun)
National Electrical Manufactures Association

19. What current and polarity is generally used with GMAW?
Welding process that joins metals by heating them with an electric arc
12 to 22 arc volts
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
DCEP (Direct Current Electrode Positive) Reverse Polarity

20. What 2 organizations designate specifications for GMAW wires?
AWS and CSA
Puddle fluidity
Controls the rate of flow of a shielding gas to the gun nozzle
Speed of the feed motor and - starting / stopping electrode feed

21. Give a description of 'pinch effect'
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
The Arc voltage
Controls the rate of flow of a shielding gas to the gun nozzle
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

22. What is the key advantage of short circuiting transfer?
These terms are quite restrictive and often technically incorrect
SMAW - GTAW
Constant- speed wire feeders and Voltage- sennsing wire feeders
Minimum distortion due to low heat input

23. What is the purpose of the shielding gas used in GMAW?
The Arc voltage
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Shielding the molten weld metal from atmospheric contamination
85%

24. In the GMAW process what does voltage control?
Puddle fluidity
20 to 200 times per second
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
The time rate of response for the current rise and fall

25. What would be an indication that the drive roll pressure is adjusted correctly?
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- speed wire feeders and Voltage- sennsing wire feeders
Wire feeds smoothly (yet will slip should a problem occur in the gun)
V groove or U groove

26. With straight polarity where is 2/3 of the arc energy?
Short- circuiting transfer - Globular transfer - Spray transfer
The negative side of a welding unit
Pressure - The rate of flow of a shielding gas
Wire feed speed - Voltage control

27. Draw a typical volt amp curve for a machine that is designed for GMAW
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Wire feed speed
Wire feed speed - Voltage control
If you dont know this check your phone

28. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Gives arc voltage values to the control system of the feeder
Puddle fluidity
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
If you dont know this check your phone

29. What effect does increasing and decreasing the inductance have on the weld?
The negative side of a welding unit
15 feet (4.5 meters)
The Arc voltage
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

30. 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
AWS and CSA
SMAW - GTAW
Wire feed speed

31. What processes are constant current (CC) power sources designed to be used with?
If you dont know this check your phone
Speed of the feed motor and - starting / stopping electrode feed
If you dont know this check your phone
SMAW - GTAW

32. What does the wire feeder control?
Motor driven generators - Transformer rectifiers - and Inverter designs
Speed of the feed motor and - starting / stopping electrode feed
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

33. What is the preferred drive roll design for solid wires?
To prevent drawing of liquid CO2 (Carbon Dioxide)
If you dont know this check your phone
Wire feed speed
V groove or U groove

34. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
V groove or U groove
Short- circuiting transfer - Globular transfer - Spray transfer
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

35. List 3 forms compressed gases may be supplied for welding
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
3
20 to 200 times per second
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

36. What does voltage do in an electrical circuit?
Constant- speed wire feeders and Voltage- sennsing wire feeders
1/4 inch to 1/2 inch
Voltage is the force that overcomes resistance to allow amperage flow
Minimum distortion due to low heat input

37. What is the main purpose of 'slope'?
Guns
The Arc voltage
To limit the short circuiting current so that spatter is reduced
To prevent leakage - Carbon Dioxide (CO2)

38. What is the required arc voltage used for short circuit transfer?
Welding process that joins metals by heating them with an electric arc
12 to 22 arc volts
To prevent drawing of liquid CO2 (Carbon Dioxide)
Controls the rate of flow of a shielding gas to the gun nozzle

39. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Flux cored wires
Higher 26 to 35 arc volts
AWS and CSA

40. What happens when the electrode extension is increased?
When the filler wire is in direct contract with the base metal
Voltage is the force that overcomes resistance to allow amperage flow
The resistace to electrical current flow increases with it. Causing the electrode to heat
Shielding the molten weld metal from atmospheric contamination

41. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
15 feet (4.5 meters)
Wire feeds smoothly (yet will slip should a problem occur in the gun)
85%
1/4 inch to 1/2 inch

42. A pull type drive system is usually used on what type of material?
By there current carrying capacity
Gives arc voltage values to the control system of the feeder
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Aluminum wire

43. 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
Spatter problems and poor weld appearance
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Generally not as accurate

44. What controls amperage when using GMAW?
The time rate of response for the current rise and fall
To prevent drawing of liquid CO2 (Carbon Dioxide)
The negative side of a welding unit
Wire feed speed

45. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
The Arc voltage
Reducing the gas source pressure to a constant working pressure
3
Duty cycle

46. What type of power source is commonly used with a voltage sensing wire feeder?
Constant current (CC)
Pressure - The rate of flow of a shielding gas
The Arc voltage
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

47. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
When the filler wire is in direct contract with the base metal
The resistace to electrical current flow increases with it. Causing the electrode to heat
(DCEP) Direct Current Electrode Positive or Reverse polarity
Guns

48. What wire are knurled drive rolls most commonly used on?
Penetration and burn - off rate of the electrode
Flux cored wires
The Arc voltage
Speed of the feed motor and - starting / stopping electrode feed

49. What power sources are used with the GMAW Process?
Voltage is the force that overcomes resistance to allow amperage flow
Motor driven generators - Transformer rectifiers - and Inverter designs
1/4 inch to 1/2 inch
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

50. List the basic equipment requirements for the GMAW process
The Arc voltage
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Constant current (CC)
These terms are quite restrictive and often technically incorrect