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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 is another term for electrode holders for GMAW?
Guns
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Wire feed speed
Pressure vessels and the piping industry

2. List the three methods of metal transfer with GMAW
Shielding the molten weld metal from atmospheric contamination
85%
Short- circuiting transfer - Globular transfer - Spray transfer
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

3. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
Cause flaking - which can clog the liner and contact tube
20 to 200 times per second
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

4. 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
Short- circuiting transfer - Globular transfer - Spray transfer
Puddle fluidity
Constant current (CC)

5. When is the metal transferred with short circuit transfer?
Penetration and burn - off rate of the electrode
Welding process that joins metals by heating them with an electric arc
The time rate of response for the current rise and fall
When the filler wire is in direct contract with the base metal

6. Draw a typical volt amp curve for a machine that is designed for GMAW
Dry ice can form within the flow control openings and cause blockage of shielding gas
When the filler wire is in direct contract with the base metal
These terms are quite restrictive and often technically incorrect
If you dont know this check your phone

7. Why is a line heater required when using GMAW?
Pressure - The rate of flow of a shielding gas
20 to 200 times per second
Dry ice can form within the flow control openings and cause blockage of shielding gas
1/4 inch to 1/2 inch

8. What does the abbreviation NEMA stand for?
The Arc voltage
Constant voltage (CV)
Flux cored wires
National Electrical Manufactures Association

9. What does a flowmeter do and what does it measure?
Insufficient current to melt the wire off cleanly
1/4 inch to 1/2 inch
These terms are quite restrictive and often technically incorrect
Controls the rate of flow of a shielding gas to the gun nozzle

10. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Guns
To limit the short circuiting current so that spatter is reduced

11. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
Penetration and burn - off rate of the electrode
The Arc voltage
National Electrical Manufactures Association

12. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
15 feet (4.5 meters)
Constant- speed wire feeders and Voltage- sennsing wire feeders
Higher 26 to 35 arc volts

13. What current and polarity is generally used with GMAW?
Motor driven generators - Transformer rectifiers - and Inverter designs
The time rate of response for the current rise and fall
DCEP (Direct Current Electrode Positive) Reverse Polarity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

14. What controls amperage when using GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Wire feed speed
Voltage is the force that overcomes resistance to allow amperage flow
Motor driven generators - Transformer rectifiers - and Inverter designs

15. What is the purpose of a regulator and what does it indicate on its gauges?
Shielding the molten weld metal from atmospheric contamination
Reducing the gas source pressure to a constant working pressure
Minutes of elapsed time continually run (out of 10 minutes)
Aluminum wire

16. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
Penetration and burn - off rate of the electrode
Wire feed speed
12 to 22 arc volts

17. What 2 organizations designate specifications for GMAW wires?
The time rate of response for the current rise and fall
AWS and CSA
(DCEP) Direct Current Electrode Positive or Reverse polarity
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

18. List several industries that would use GMAW
To limit the short circuiting current so that spatter is reduced
Pressure vessels and the piping industry
Gives arc voltage values to the control system of the feeder
Flux cored wires

19. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Insufficient current to melt the wire off cleanly
If you dont know this check your phone
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
(DCEP) Direct Current Electrode Positive or Reverse polarity

20. How many times per second does short circuiting take place?
These terms are quite restrictive and often technically incorrect
Pressure vessels and the piping industry
85%
20 to 200 times per second

21. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
These terms are quite restrictive and often technically incorrect
(DCEP) Direct Current Electrode Positive or Reverse polarity
Gives arc voltage values to the control system of the feeder
If you dont know this check your phone

22. What does voltage do in an electrical circuit?
These terms are quite restrictive and often technically incorrect
Voltage is the force that overcomes resistance to allow amperage flow
20 to 200 times per second
Gas metal arc welding

23. What is the key advantage of short circuiting transfer?
Welding process that joins metals by heating them with an electric arc
Controls the rate of flow of a shielding gas to the gun nozzle
Minimum distortion due to low heat input
Constant- speed wire feeders and Voltage- sennsing wire feeders

24. What type of power source is commonly used with a voltage sensing wire feeder?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
85%
Constant current (CC)
Shielding the molten weld metal from atmospheric contamination

25. List 3 wire drive systems and give a short description of each
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Constant current (CC)
Pressure vessels and the piping industry
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

26. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
Pressure - The rate of flow of a shielding gas
Penetration and burn - off rate of the electrode
National Electrical Manufactures Association

27. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Controls the rate of flow of a shielding gas to the gun nozzle
Duty cycle
12 to 22 arc volts

28. What output on the welding machine is used to rate the duty cycle?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Minutes of elapsed time continually run (out of 10 minutes)
Puddle fluidity
5.8 to 12.5 L/min

29. 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
The negative side of a welding unit
DCEP (Direct Current Electrode Positive) Reverse Polarity
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

30. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
1/4 inch to 1/2 inch
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Reducing the gas source pressure to a constant working pressure

31. What 2 controls are found on a GMAW set- up?
Cause flaking - which can clog the liner and contact tube
Wire feed speed - Voltage control
Flux cored wires
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

32. What is a solenoid valve and what actuates it?
Spatter problems and poor weld appearance
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Aluminum wire
Constant- speed wire feeders and Voltage- sennsing wire feeders

33. What is the purpose of the shielding gas used in GMAW?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Shielding the molten weld metal from atmospheric contamination
National Electrical Manufactures Association
Pressure - The rate of flow of a shielding gas

34. What is the main purpose of 'slope'?
Penetration and burn - off rate of the electrode
Flux cored wires
To limit the short circuiting current so that spatter is reduced
National Electrical Manufactures Association

35. What type of power source is used with a constant speed wire feeder?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Constant voltage (CV)
V groove or U groove
Insufficient current to melt the wire off cleanly

36. In the GMAW process what does voltage control?
Gives arc voltage values to the control system of the feeder
Puddle fluidity
Higher 26 to 35 arc volts
Pressure - The rate of flow of a shielding gas

37. What is the maximum distance that hard wire can be successfully pushed?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Dry ice can form within the flow control openings and cause blockage of shielding gas
12 to 22 arc volts
15 feet (4.5 meters)

38. How are GMAW guns rated?
Wire feed speed
Flux cored wires
By there current carrying capacity
Wire feed speed - Voltage control

39. What is the recommended electrode stick- out for .035 solid wire?
To prevent leakage - Carbon Dioxide (CO2)
20 to 200 times per second
1/4 inch to 1/2 inch
3

40. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
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
85%
Spatter problems and poor weld appearance

41. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
When the filler wire is in direct contract with the base metal
Wire feed speed
3

42. What does inductance control?
The time rate of response for the current rise and fall
...
Constant voltage (CV)
Motor driven generators - Transformer rectifiers - and Inverter designs

43. Why must CO2 cylinders be used in the vertical position?
Pressure vessels and the piping industry
To prevent drawing of liquid CO2 (Carbon Dioxide)
The resistace to electrical current flow increases with it. Causing the electrode to heat
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

44. What does the wire feeder control?
Motor driven generators - Transformer rectifiers - and Inverter designs
Aluminum wire
Speed of the feed motor and - starting / stopping electrode feed
5.8 to 12.5 L/min

45. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Wire feed speed - Voltage control
Constant current (CC)

46. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Penetration and burn - off rate of the electrode
Wire feed speed - Voltage control
Wire feed speed
Gives arc voltage values to the control system of the feeder

47. A pull type drive system is usually used on what type of material?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
12 to 22 arc volts
Aluminum wire
Minutes of elapsed time continually run (out of 10 minutes)

48. 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
Pressure - The rate of flow of a shielding gas
To prevent leakage - Carbon Dioxide (CO2)
Constant current (CC)

49. What power sources are used with the GMAW Process?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Pressure vessels and the piping industry
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Motor driven generators - Transformer rectifiers - and Inverter designs

50. What does the term GMAW identify?
Cause flaking - which can clog the liner and contact tube
Gas metal arc welding
Dry ice can form within the flow control openings and cause blockage of shielding gas
Reducing the gas source pressure to a constant working pressure