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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
1/4 inch to 1/2 inch
12 to 22 arc volts
Reducing the gas source pressure to a constant working pressure

2. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
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

3. What current and polarity is generally used with GMAW?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
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
The time rate of response for the current rise and fall

4. What is the main purpose of 'slope'?
...
To limit the short circuiting current so that spatter is reduced
Cause flaking - which can clog the liner and contact tube
The Arc voltage

5. What is the preferred drive roll design for solid wires?
Generally not as accurate
V groove or U groove
The time rate of response for the current rise and fall
Guns

6. What is the required arc voltage used for short circuit transfer?
The time rate of response for the current rise and fall
12 to 22 arc volts
To prevent drawing of liquid CO2 (Carbon Dioxide)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

7. What effect does increasing and decreasing the inductance have on the weld?
Higher 26 to 35 arc volts
To limit the short circuiting current so that spatter is reduced
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

8. How are GMAW guns rated?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Shielding the molten weld metal from atmospheric contamination
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By there current carrying capacity

9. Why must CO2 cylinders be used in the vertical position?
Duty cycle
The negative side of a welding unit
AWS and CSA
To prevent drawing of liquid CO2 (Carbon Dioxide)

10. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Flux cored wires
Pressure vessels and the piping industry
3
Penetration and burn - off rate of the electrode

11. What is the effect of too much slope?
(DCEP) Direct Current Electrode Positive or 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
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Insufficient current to melt the wire off cleanly

12. What is another term for electrode holders for GMAW?
Aluminum wire
Spatter problems and poor weld appearance
Guns
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

13. List the three methods of metal transfer with GMAW
Wire feed speed - Voltage control
Short- circuiting transfer - Globular transfer - Spray transfer
Higher 26 to 35 arc volts
15 feet (4.5 meters)

14. Give a description of 'pinch effect'
To limit the short circuiting current so that spatter is reduced
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
DCEP (Direct Current Electrode Positive) Reverse Polarity
Penetration and burn - off rate of the electrode

15. What is a solenoid valve and what actuates it?
By there current carrying capacity
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
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

16. Why is a fiber washer required and what cylinder gas requires it?
Insufficient current to melt the wire off cleanly
To prevent leakage - Carbon Dioxide (CO2)
(DCEP) Direct Current Electrode Positive or Reverse polarity
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

17. Why is globular transfer generally avoided with GMAW?
To limit the short circuiting current so that spatter is reduced
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Aluminum wire
Spatter problems and poor weld appearance

18. A pull type drive system is usually used on what type of material?
Minutes of elapsed time continually run (out of 10 minutes)
Aluminum wire
To limit the short circuiting current so that spatter is reduced
Speed of the feed motor and - starting / stopping electrode feed

19. List the basic equipment requirements for the GMAW process
These terms are quite restrictive and often technically incorrect
Guns
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Spatter problems and poor weld appearance

20. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Pressure - The rate of flow of a shielding gas
(DCEP) Direct Current Electrode Positive or Reverse polarity
Minimum distortion due to low heat input
Minutes of elapsed time continually run (out of 10 minutes)

21. List 3 wire drive systems and give a short description of each
AWS and CSA
Generally not as accurate
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
V groove or U groove

22. Give a brief description of the GMAW process
To limit the short circuiting current so that spatter is reduced
Welding process that joins metals by heating them with an electric arc
Minimum distortion due to low heat input
Wire feeds smoothly (yet will slip should a problem occur in the gun)

23. List the factors that determine the mode of metal transfer
...
3
Gas metal arc welding
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

24. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
...
Minimum distortion due to low heat input
5.8 to 12.5 L/min

25. How many times per second does short circuiting take place?
Controls the rate of flow of a shielding gas to the gun nozzle
Motor driven generators - Transformer rectifiers - and Inverter designs
Gives arc voltage values to the control system of the feeder
20 to 200 times per second

26. What is the maximum distance that hard wire can be successfully pushed?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
15 feet (4.5 meters)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Guns

27. What type of power source is commonly used with a voltage sensing wire feeder?
Puddle fluidity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Generally not as accurate
Constant current (CC)

28. In the GMAW process what does voltage control?
National Electrical Manufactures Association
Constant current (CC)
Puddle fluidity
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 power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
To prevent drawing of liquid CO2 (Carbon Dioxide)
Dry ice can form within the flow control openings and cause blockage of shielding gas
Constant- speed wire feeders and Voltage- sennsing wire feeders

30. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Insufficient current to melt the wire off cleanly
If you dont know this check your phone
85%
Gives arc voltage values to the control system of the feeder

31. What controls the wire speed on a voltage sensing wire feeder?
Reducing the gas source pressure to a constant working pressure
The resistace to electrical current flow increases with it. Causing the electrode to heat
5.8 to 12.5 L/min
The Arc voltage

32. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Constant current (CC)
Voltage is the force that overcomes resistance to allow amperage flow
Cause flaking - which can clog the liner and contact tube

33. What is a typical flow rate of CO2 for short circuit transfer?
Flux cored wires
SMAW - GTAW
5.8 to 12.5 L/min
Guns

34. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
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

35. What does the term GMAW identify?
SMAW - GTAW
Constant current (CC)
Gas metal arc welding
The time rate of response for the current rise and fall

36. What 2 organizations designate specifications for GMAW wires?
Wire feed speed
3
AWS and CSA
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

37. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
Wire feed speed
Wire feeds smoothly (yet will slip should a problem occur in the gun)
The negative side of a welding unit

38. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
...
Constant current (CC)
These terms are quite restrictive and often technically incorrect
Short- circuiting transfer - Globular transfer - Spray transfer

39. List several industries that would use GMAW
Higher 26 to 35 arc volts
These terms are quite restrictive and often technically incorrect
Pressure vessels and the piping industry
(DCEP) Direct Current Electrode Positive or Reverse polarity

40. What is the recommended electrode stick- out for .035 solid wire?
Minutes of elapsed time continually run (out of 10 minutes)
85%
5.8 to 12.5 L/min
1/4 inch to 1/2 inch

41. What output on the welding machine is used to rate the duty cycle?
Insufficient current to melt the wire off cleanly
Flux cored wires
Minutes of elapsed time continually run (out of 10 minutes)
85%

42. List 3 forms compressed gases may be supplied for welding
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
By there current carrying capacity
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

43. A 10 minute cycle of welding time vs cooling time a given machine can handle.
3
(DCEP) Direct Current Electrode Positive or Reverse polarity
Duty cycle
Constant voltage (CV)

44. What does inductance control?
20 to 200 times per second
DCEP (Direct Current Electrode Positive) Reverse Polarity
15 feet (4.5 meters)
The time rate of response for the current rise and fall

45. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
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Penetration and burn - off rate of the electrode
The resistace to electrical current flow increases with it. Causing the electrode to heat
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

46. When is the metal transferred with short circuit transfer?
Voltage is the force that overcomes resistance to allow amperage flow
Duty cycle
Flux cored wires
When the filler wire is in direct contract with the base metal

47. What does the wire feeder control?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
The resistace to electrical current flow increases with it. Causing the electrode to heat
Speed of the feed motor and - starting / stopping electrode feed
Controls the rate of flow of a shielding gas to the gun nozzle

48. With straight polarity where is 2/3 of the arc energy?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Insufficient current to melt the wire off cleanly
The negative side of a welding unit
AWS and CSA

49. What is an advantage of pulsed arc transfer with GMAW?
When the filler wire is in direct contract with the base metal
Speed of the feed motor and - starting / stopping electrode feed
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Constant voltage (CV)

50. What is the purpose of a regulator and what does it indicate on its gauges?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Spatter problems and poor weld appearance
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Reducing the gas source pressure to a constant working pressure