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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.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

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 the preferred drive roll design for solid wires?
Constant- speed wire feeders and Voltage- sennsing wire feeders
The time rate of response for the current rise and fall
V groove or U groove
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

2. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
...
3
When the filler wire is in direct contract with the base metal
Flux cored wires

3. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Speed of the feed motor and - starting / stopping electrode feed
Constant voltage (CV)
(DCEP) Direct Current Electrode Positive or Reverse polarity

4. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Constant voltage (CV)
3
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Cause flaking - which can clog the liner and contact tube

5. What processes are constant current (CC) power sources designed to be used with?
Minutes of elapsed time continually run (out of 10 minutes)
SMAW - GTAW
1/4 inch to 1/2 inch
These terms are quite restrictive and often technically incorrect

6. Give a brief description of the GMAW process
Short- circuiting transfer - Globular transfer - Spray transfer
20 to 200 times per second
Welding process that joins metals by heating them with an electric arc
DCEP (Direct Current Electrode Positive) Reverse Polarity

7. How many times per second does short circuiting take place?
20 to 200 times per second
Minutes of elapsed time continually run (out of 10 minutes)
Minimum distortion due to low heat input
Welding process that joins metals by heating them with an electric arc

8. Give a description of 'pinch effect'
The Arc voltage
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
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Puddle fluidity

9. In the GMAW process what does voltage control?
Insufficient current to melt the wire off cleanly
20 to 200 times per second
These terms are quite restrictive and often technically incorrect
Puddle fluidity

10. What does inductance control?
5.8 to 12.5 L/min
The time rate of response for the current rise and fall
Short- circuiting transfer - Globular transfer - Spray transfer
If you dont know this check your phone

11. With straight polarity where is 2/3 of the arc energy?
20 to 200 times per second
Pressure vessels and the piping industry
Higher 26 to 35 arc volts
The negative side of a welding unit

12. What is the purpose of the shielding gas used in GMAW?
Reducing the gas source pressure to a constant working pressure
When the filler wire is in direct contract with the base metal
Duty cycle
Shielding the molten weld metal from atmospheric contamination

13. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Generally not as accurate
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Pressure vessels and the piping industry

14. What type of power source is used with a constant speed wire feeder?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Wire feed speed - Voltage control
Constant voltage (CV)
Generally not as accurate

15. What does the term GMAW identify?
Higher 26 to 35 arc volts
Gas metal arc welding
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
The Arc voltage

16. What output on the welding machine is used to rate the duty cycle?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Shielding the molten weld metal from atmospheric contamination
Minutes of elapsed time continually run (out of 10 minutes)
Guns

17. List the factors that determine the mode of metal transfer
Constant voltage (CV)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

18. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
3
Higher 26 to 35 arc volts
Insufficient current to melt the wire off cleanly
Cause flaking - which can clog the liner and contact tube

19. What happens when the electrode extension is increased?
Spatter problems and poor weld appearance
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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

20. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Welding process that joins metals by heating them with an electric arc
Gives arc voltage values to the control system of the feeder
If you dont know this check your phone
Spatter problems and poor weld appearance

21. What wire are knurled drive rolls most commonly used on?
To limit the short circuiting current so that spatter is reduced
Flux cored wires
12 to 22 arc volts
The resistace to electrical current flow increases with it. Causing the electrode to heat

22. What 2 controls are found on a GMAW set- up?
The time rate of response for the current rise and fall
Wire feed speed - Voltage control
If you dont know this check your phone
Spatter problems and poor weld appearance

23. What controls the wire speed on a voltage sensing wire feeder?
Voltage is the force that overcomes resistance to allow amperage flow
The Arc voltage
Short- circuiting transfer - Globular transfer - Spray transfer
The negative side of a welding unit

24. Draw a typical volt amp curve for a machine that is designed for GMAW
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Minutes of elapsed time continually run (out of 10 minutes)
Cause flaking - which can clog the liner and contact tube
Wire feed speed - Voltage control

25. What is another term for electrode holders for GMAW?
National Electrical Manufactures Association
Guns
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Penetration and burn - off rate of the electrode

26. What is a typical flow rate of CO2 for short circuit transfer?
SMAW - GTAW
If you dont know this check your phone
Guns
5.8 to 12.5 L/min

27. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
Wire feed speed - Voltage control
Higher 26 to 35 arc volts
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

28. 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
Minimum distortion due to low heat input
3
If you dont know this check your phone

29. List 3 wire drive systems and give a short description of each
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
Pressure vessels and the piping industry
Cause flaking - which can clog the liner and contact tube

30. What would be an indication that the drive roll pressure is adjusted correctly?
5.8 to 12.5 L/min
Minimum distortion due to low heat input
Wire feeds smoothly (yet will slip should a problem occur in the gun)
The time rate of response for the current rise and fall

31. What effect does increasing and decreasing the inductance have on the weld?
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
Constant current (CC)
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. What type of power source is commonly used with a voltage sensing wire feeder?
3
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Constant current (CC)
Short- circuiting transfer - Globular transfer - Spray transfer

33. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Gas metal arc welding
Aluminum wire

34. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Constant- speed wire feeders and Voltage- sennsing wire feeders
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

35. What is the effect of too much slope?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Puddle fluidity
3
Insufficient current to melt the wire off cleanly

36. What controls amperage when using GMAW?
Minimum distortion due to low heat input
Wire feed speed
Shielding the molten weld metal from atmospheric contamination
Pressure vessels and the piping industry

37. 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
85%
Constant voltage (CV)
By there current carrying capacity

38. What is an advantage of pulsed arc transfer with GMAW?
Wire feed speed - Voltage control
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
If you dont know this check your phone
If you dont know this check your phone

39. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Constant voltage (CV)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
20 to 200 times per second

40. What is the maximum distance that hard wire can be successfully pushed?
Insufficient current to melt the wire off cleanly
Short- circuiting transfer - Globular transfer - Spray transfer
Penetration and burn - off rate of the electrode
15 feet (4.5 meters)

41. List several industries that would use GMAW
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Pressure vessels and the piping industry
Higher 26 to 35 arc volts
Constant- speed wire feeders and Voltage- sennsing wire feeders

42. What current and polarity is generally used with GMAW?
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
Duty cycle
DCEP (Direct Current Electrode Positive) Reverse Polarity

43. What is the recommended electrode stick- out for .035 solid wire?
Duty cycle
DCEP (Direct Current Electrode Positive) Reverse Polarity
1/4 inch to 1/2 inch
The negative side of a welding unit

44. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Aluminum wire
If you dont know this check your phone
(DCEP) Direct Current Electrode Positive or Reverse polarity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

45. When is the metal transferred with short circuit transfer?
Pressure vessels and the piping industry
Flux cored wires
When the filler wire is in direct contract with the base metal
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

46. What is the main purpose of 'slope'?
Duty cycle
Motor driven generators - Transformer rectifiers - and Inverter designs
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
To limit the short circuiting current so that spatter is reduced

47. How are GMAW guns rated?
By there current carrying capacity
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
5.8 to 12.5 L/min
85%

48. Why is the term GMAW preferred over MIG or MAG?
Minutes of elapsed time continually run (out of 10 minutes)
These terms are quite restrictive and often technically incorrect
3
Reducing the gas source pressure to a constant working pressure

49. What 2 organizations designate specifications for GMAW wires?
Voltage is the force that overcomes resistance to allow amperage flow
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
AWS and CSA
Spatter problems and poor weld appearance

50. Regulators control_____________ flowmeters SHOW____________.
Puddle fluidity
The negative side of a welding unit
The Arc voltage
Pressure - The rate of flow of a shielding gas