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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. In the GMAW process what does amperage control?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Penetration and burn - off rate of the electrode
SMAW - GTAW
To prevent leakage - Carbon Dioxide (CO2)

2. What does a flowmeter do and what does it measure?
Gas metal arc welding
Controls the rate of flow of a shielding gas to the gun nozzle
Minutes of elapsed time continually run (out of 10 minutes)
Higher 26 to 35 arc volts

3. 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
Controls the rate of flow of a shielding gas to the gun nozzle
Wire feed speed
The resistace to electrical current flow increases with it. Causing the electrode to heat

4. What 2 controls are found on a GMAW set- up?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Wire feed speed - Voltage control
Motor driven generators - Transformer rectifiers - and Inverter designs
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

5. In the GMAW process what does voltage control?
Constant voltage (CV)
Aluminum wire
Puddle fluidity
Cause flaking - which can clog the liner and contact tube

6. What controls the wire speed on a voltage sensing wire feeder?
Constant voltage (CV)
The Arc voltage
Constant- speed wire feeders and Voltage- sennsing wire feeders
By there current carrying capacity

7. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
Motor driven generators - Transformer rectifiers - and Inverter designs
AWS and CSA
Wire feed speed - Voltage control

8. How are GMAW guns rated?
Reducing the gas source pressure to a constant working pressure
3
By there current carrying capacity
Shielding the molten weld metal from atmospheric contamination

9. What is the required arc voltage used for short circuit transfer?
Constant- speed wire feeders and Voltage- sennsing wire feeders
12 to 22 arc volts
Reducing the gas source pressure to a constant working pressure
V groove or U groove

10. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
To limit the short circuiting current so that spatter is reduced
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

11. When is the metal transferred with short circuit transfer?
National Electrical Manufactures Association
When the filler wire is in direct contract with the base metal
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)

12. What controls amperage when using GMAW?
20 to 200 times per second
AWS and CSA
Wire feed speed
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

13. 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
3
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Spatter problems and poor weld appearance

14. 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)
National Electrical Manufactures Association
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

15. What 2 organizations designate specifications for GMAW wires?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Welding process that joins metals by heating them with an electric arc
AWS and CSA
If you dont know this check your phone

16. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Minimum distortion due to low heat input
V groove or U groove
12 to 22 arc volts
3

17. What wire are knurled drive rolls most commonly used on?
When the filler wire is in direct contract with the base metal
Flux cored wires
The negative side of a welding unit
Duty cycle

18. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
3
12 to 22 arc volts
V groove or U groove

19. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Voltage is the force that overcomes resistance to allow amperage flow
Guns
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

20. A pull type drive system is usually used on what type of material?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Aluminum wire
Constant- speed wire feeders and Voltage- sennsing wire feeders
(DCEP) Direct Current Electrode Positive or Reverse polarity

21. What is the recommended electrode stick- out for .035 solid wire?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Flux cored wires
1/4 inch to 1/2 inch
Motor driven generators - Transformer rectifiers - and Inverter designs

22. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
Constant voltage (CV)
Pressure vessels and the piping industry
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

23. What is the purpose of the shielding gas used in GMAW?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Short- circuiting transfer - Globular transfer - Spray transfer
Wire feed speed - Voltage control
Shielding the molten weld metal from atmospheric contamination

24. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Duty cycle
(DCEP) Direct Current Electrode Positive or Reverse polarity

25. Draw a typical volt amp curve for a machine that is designed for GMAW
If you dont know this check your phone
Insufficient current to melt the wire off cleanly
Flux cored wires
Controls the rate of flow of a shielding gas to the gun nozzle

26. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
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
The Arc voltage
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

27. List the basic equipment requirements for the GMAW process
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
12 to 22 arc volts
Wire feed speed
Minimum distortion due to low heat input

28. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
Cause flaking - which can clog the liner and contact tube
DCEP (Direct Current Electrode Positive) Reverse Polarity
Wire feeds smoothly (yet will slip should a problem occur in the gun)

29. What does the abbreviation NEMA stand for?
Constant voltage (CV)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
To prevent drawing of liquid CO2 (Carbon Dioxide)
National Electrical Manufactures Association

30. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Gives arc voltage values to the control system of the feeder
...
These terms are quite restrictive and often technically incorrect
Higher 26 to 35 arc volts

31. Give a description of 'pinch effect'
SMAW - GTAW
Wire feeds smoothly (yet will slip should a problem occur in the gun)
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

32. What does inductance control?
Wire feed speed - Voltage control
SMAW - GTAW
If you dont know this check your phone
The time rate of response for the current rise and fall

33. 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
If you dont know this check your phone
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Duty cycle

34. With straight polarity where is 2/3 of the arc energy?
Insufficient current to melt the wire off cleanly
The negative side of a welding unit
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
By there current carrying capacity

35. What is the maximum distance that hard wire can be successfully pushed?
AWS and CSA
15 feet (4.5 meters)
Puddle fluidity
Gives arc voltage values to the control system of the feeder

36. What is a solenoid valve and what actuates it?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Pressure vessels and the piping industry
...
Duty cycle

37. List 3 forms compressed gases may be supplied for welding
Constant- speed wire feeders and Voltage- sennsing wire feeders
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
If you dont know this check your phone
To prevent leakage - Carbon Dioxide (CO2)

38. What happens when the electrode extension is increased?
Motor driven generators - Transformer rectifiers - and Inverter designs
Guns
85%
The resistace to electrical current flow increases with it. Causing the electrode to heat

39. What current and polarity is generally used with GMAW?
Reducing the gas source pressure to a constant working pressure
When the filler wire is in direct contract with the base metal
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

40. Why is a line heater required when using GMAW?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Speed of the feed motor and - starting / stopping electrode feed
Minimum distortion due to low heat input
Dry ice can form within the flow control openings and cause blockage of shielding gas

41. What type of power source is used with a constant speed wire feeder?
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
Reducing the gas source pressure to a constant working pressure
Constant voltage (CV)

42. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Reducing the gas source pressure to a constant working pressure
If you dont know this check your phone
Spatter problems and poor weld appearance
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

43. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
The time rate of response for the current rise and fall
Pressure - The rate of flow of a shielding gas
AWS and CSA

44. 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
V groove or U groove
Shielding the molten weld metal from atmospheric contamination
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

45. List several industries that would use GMAW
Gives arc voltage values to the control system of the feeder
Pressure vessels and the piping industry
15 feet (4.5 meters)
Generally not as accurate

46. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
5.8 to 12.5 L/min
...
Wire feeds smoothly (yet will slip should a problem occur in the gun)
The resistace to electrical current flow increases with it. Causing the electrode to heat

47. 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
Duty cycle
These terms are quite restrictive and often technically incorrect

48. What is the preferred drive roll design for solid wires?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
DCEP (Direct Current Electrode Positive) Reverse Polarity
V groove or U groove
Flux cored wires

49. Why is the term GMAW preferred over MIG or MAG?
When the filler wire is in direct contract with the base metal
85%
Aluminum wire
These terms are quite restrictive and often technically incorrect

50. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
(DCEP) Direct Current Electrode Positive or Reverse polarity
Generally not as accurate