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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 effect of too much slope?
The Arc voltage
SMAW - GTAW
To prevent leakage - Carbon Dioxide (CO2)
Insufficient current to melt the wire off cleanly

2. Why is a line heater required when using GMAW?
...
1/4 inch to 1/2 inch
Dry ice can form within the flow control openings and cause blockage of shielding gas
Pressure vessels and the piping industry

3. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
Welding process that joins metals by heating them with an electric arc
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
To prevent drawing of liquid CO2 (Carbon Dioxide)

4. 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
The Arc voltage
Flux cored wires
The negative side of a welding unit

5. What is the maximum distance that hard wire can be successfully pushed?
(DCEP) Direct Current Electrode Positive or Reverse polarity
AWS and CSA
20 to 200 times per second
15 feet (4.5 meters)

6. What 2 organizations designate specifications for GMAW wires?
Voltage is the force that overcomes resistance to allow amperage flow
If you dont know this check your phone
AWS and CSA
Minimum distortion due to low heat input

7. List several industries that would use GMAW
Guns
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
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

8. What is the required arc voltage used for short circuit transfer?
National Electrical Manufactures Association
3
Puddle fluidity
12 to 22 arc volts

9. What is the recommended electrode stick- out for .035 solid wire?
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
1/4 inch to 1/2 inch
If you dont know this check your phone
Pressure vessels and the piping industry

10. Regulators control_____________ flowmeters SHOW____________.
Minutes of elapsed time continually run (out of 10 minutes)
20 to 200 times per second
Pressure - The rate of flow of a shielding gas
Pressure vessels and the piping industry

11. What happens when the electrode extension is increased?
Insufficient current to melt the wire off cleanly
The resistace to electrical current flow increases with it. Causing the electrode to heat
To prevent leakage - Carbon Dioxide (CO2)
Guns

12. Give a description of 'pinch effect'
Welding process that joins metals by heating them with an electric arc
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
AWS and CSA

13. List the three methods of metal transfer with GMAW
By there current carrying capacity
Short- circuiting transfer - Globular transfer - Spray transfer
SMAW - GTAW
To limit the short circuiting current so that spatter is reduced

14. What would be an indication that the drive roll pressure is adjusted correctly?
Short- circuiting transfer - Globular transfer - Spray transfer
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Wire feeds smoothly (yet will slip should a problem occur in the gun)
By there current carrying capacity

15. With straight polarity where is 2/3 of the arc energy?
Spatter problems and poor weld appearance
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
The negative side of a welding unit
Motor driven generators - Transformer rectifiers - and Inverter designs

16. What does voltage do in an electrical circuit?
Welding process that joins metals by heating them with an electric arc
Aluminum wire
Minimum distortion due to low heat input
Voltage is the force that overcomes resistance to allow amperage flow

17. What is the preferred drive roll design for solid wires?
15 feet (4.5 meters)
V groove or U groove
85%
Puddle fluidity

18. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
National Electrical Manufactures Association
If you dont know this check your phone
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
The Arc voltage

19. What effect does increasing and decreasing the inductance have on the weld?
Gives arc voltage values to the control system of the feeder
The negative side of a welding unit
Duty cycle
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

20. What does inductance control?
To prevent drawing of liquid CO2 (Carbon Dioxide)
SMAW - GTAW
AWS and CSA
The time rate of response for the current rise and fall

21. What controls amperage when using GMAW?
The time rate of response for the current rise and fall
Wire feed speed
Higher 26 to 35 arc volts
1/4 inch to 1/2 inch

22. How many times per second does short circuiting take place?
20 to 200 times per second
Flux cored wires
Motor driven generators - Transformer rectifiers - and Inverter designs
Wire feed speed - Voltage control

23. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
Puddle fluidity
12 to 22 arc volts
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

24. A pull type drive system is usually used on what type of material?
Aluminum wire
National Electrical Manufactures Association
Pressure - The rate of flow of a shielding gas
AWS and CSA

25. What does the term GMAW identify?
...
Spatter problems and poor weld appearance
Wire feed speed
Gas metal arc welding

26. 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
The Arc voltage
Minutes of elapsed time continually run (out of 10 minutes)
Guns

27. What is another term for electrode holders for GMAW?
Gives arc voltage values to the control system of the feeder
Guns
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

28. How are GMAW guns rated?
To limit the short circuiting current so that spatter is reduced
Speed of the feed motor and - starting / stopping electrode feed
Pressure - The rate of flow of a shielding gas
By there current carrying capacity

29. What is the purpose of a regulator and what does it indicate on its gauges?
Voltage is the force that overcomes resistance to allow amperage flow
Reducing the gas source pressure to a constant working pressure
The resistace to electrical current flow increases with it. Causing the electrode to heat
The negative side of a welding unit

30. What type of power source is used with a constant speed wire feeder?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Constant voltage (CV)
12 to 22 arc volts
(DCEP) Direct Current Electrode Positive or Reverse polarity

31. What are the 2 types of wire feeders available?
Minimum distortion due to low heat input
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
Constant- speed wire feeders and Voltage- sennsing wire feeders
Speed of the feed motor and - starting / stopping electrode feed

32. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
The Arc voltage
Reducing the gas source pressure to a constant working pressure
Cause flaking - which can clog the liner and contact tube
Controls the rate of flow of a shielding gas to the gun nozzle

33. What power sources are used with the GMAW Process?
Reducing the gas source pressure to a constant working pressure
15 feet (4.5 meters)
Constant current (CC)
Motor driven generators - Transformer rectifiers - and Inverter designs

34. Why must CO2 cylinders be used in the vertical position?
Pressure - The rate of flow of a shielding gas
Pressure vessels and the piping industry
To prevent drawing of liquid CO2 (Carbon Dioxide)
Generally not as accurate

35. Why is globular transfer generally avoided with GMAW?
5.8 to 12.5 L/min
Shielding the molten weld metal from atmospheric contamination
Spatter problems and poor weld appearance
Constant voltage (CV)

36. What does the wire feeder control?
12 to 22 arc volts
Controls the rate of flow of a shielding gas to the gun nozzle
Pressure - The rate of flow of a shielding gas
Speed of the feed motor and - starting / stopping electrode feed

37. What is an advantage of pulsed arc transfer with GMAW?
Shielding the molten weld metal from atmospheric contamination
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Minutes of elapsed time continually run (out of 10 minutes)
Reducing the gas source pressure to a constant working pressure

38. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Controls the rate of flow of a shielding gas to the gun nozzle
SMAW - GTAW
Generally not as accurate
...

39. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
Generally not as accurate
Puddle fluidity
1/4 inch to 1/2 inch

40. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
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

41. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
If you dont know this check your phone
Spatter problems and poor weld appearance
...
Gives arc voltage values to the control system of the feeder

42. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
(DCEP) Direct Current Electrode Positive or Reverse polarity
...
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
V groove or U groove

43. 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
Flux cored wires
Shielding the molten weld metal from atmospheric contamination
1/4 inch to 1/2 inch

44. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
The negative side of a welding unit
3
Minimum distortion due to low heat input
Pressure vessels and the piping industry

45. In the GMAW process what does amperage control?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Constant current (CC)
Penetration and burn - off rate of the electrode
Wire feeds smoothly (yet will slip should a problem occur in the gun)

46. What 2 controls are found on a GMAW set- up?
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
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Wire feed speed - Voltage control

47. Draw a typical volt amp curve for a machine that is designed for GMAW
Pressure vessels and the piping industry
If you dont know this check your phone
Controls the rate of flow of a shielding gas to the gun nozzle
Flux cored wires

48. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
The negative side of a welding unit
AWS and CSA
85%
(DCEP) Direct Current Electrode Positive or Reverse polarity

49. What does a flowmeter do and what does it measure?
National Electrical Manufactures Association
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
By there current carrying capacity

50. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
Insufficient current to melt the wire off cleanly
These terms are quite restrictive and often technically incorrect
The negative side of a welding unit