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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. List the basic equipment requirements for the GMAW process
Voltage is the force that overcomes resistance to allow amperage flow
Shielding the molten weld metal from atmospheric contamination
Gas metal arc welding
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

2. Draw a typical volt amp curve for a machine that is designed for GMAW
Cause flaking - which can clog the liner and contact tube
12 to 22 arc volts
The negative side of a welding unit
If you dont know this check your phone

3. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Wire feed speed - Voltage control
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

4. What does a flowmeter do and what does it measure?
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
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Puddle fluidity
Controls the rate of flow of a shielding gas to the gun nozzle

5. What does the abbreviation NEMA stand for?
The Arc voltage
Welding process that joins metals by heating them with an electric arc
National Electrical Manufactures Association
By there current carrying capacity

6. List 3 wire drive systems and give a short description of each
Reducing the gas source pressure to a constant working pressure
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
Spatter problems and poor weld appearance
The Arc voltage

7. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Minimum distortion due to low heat input
These terms are quite restrictive and often technically incorrect
Voltage is the force that overcomes resistance to allow amperage flow
Cause flaking - which can clog the liner and contact tube

8. What power sources are used with the GMAW Process?
Minutes of elapsed time continually run (out of 10 minutes)
Speed of the feed motor and - starting / stopping electrode feed
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
Motor driven generators - Transformer rectifiers - and Inverter designs

9. What is an advantage of pulsed arc transfer with GMAW?
Welding process that joins metals by heating them with an electric arc
Constant voltage (CV)
Controls the rate of flow of a shielding gas to the gun nozzle
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

10. What is the purpose of a regulator and what does it indicate on its gauges?
20 to 200 times per second
Reducing the gas source pressure to a constant working pressure
Voltage is the force that overcomes resistance to allow amperage flow
Constant current (CC)

11. How many times per second does short circuiting take place?
Short- circuiting transfer - Globular transfer - Spray transfer
20 to 200 times per second
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

12. Give a brief description of the GMAW process
The negative side of a welding unit
Welding process that joins metals by heating them with an electric arc
Puddle fluidity
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

13. What type of power source is used with a constant speed wire feeder?
Puddle fluidity
DCEP (Direct Current Electrode Positive) Reverse Polarity
Constant voltage (CV)
Higher 26 to 35 arc volts

14. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
To prevent leakage - Carbon Dioxide (CO2)
Constant voltage (CV)
Higher 26 to 35 arc volts
Aluminum wire

15. What 2 organizations designate specifications for GMAW wires?
Wire feed speed
AWS and CSA
Puddle fluidity
Short- circuiting transfer - Globular transfer - Spray transfer

16. What would be an indication that the drive roll pressure is adjusted correctly?
Reducing the gas source pressure to a constant working pressure
Constant- speed wire feeders and Voltage- sennsing wire feeders
Wire feed speed
Wire feeds smoothly (yet will slip should a problem occur in the gun)

17. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
12 to 22 arc volts
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
...

18. Regulators control_____________ flowmeters SHOW____________.
Minimum distortion due to low heat input
Wire feed speed
Pressure - The rate of flow of a shielding gas
Cause flaking - which can clog the liner and contact tube

19. List several industries that would use GMAW
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
85%
Pressure vessels and the piping industry

20. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Gives arc voltage values to the control system of the feeder
Minimum distortion due to low heat input
When the filler wire is in direct contract with the base metal

21. A pull type drive system is usually used on what type of material?
Minimum distortion due to low heat input
Aluminum wire
85%
Wire feed speed - Voltage control

22. What wire are knurled drive rolls most commonly used on?
Higher 26 to 35 arc volts
Flux cored wires
Voltage is the force that overcomes resistance to allow amperage flow
Insufficient current to melt the wire off cleanly

23. What is another term for electrode holders for GMAW?
National Electrical Manufactures Association
Flux cored wires
Voltage is the force that overcomes resistance to allow amperage flow
Guns

24. What is the preferred drive roll design for solid wires?
Flux cored wires
V groove or U groove
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Motor driven generators - Transformer rectifiers - and Inverter designs

25. Why is a fiber washer required and what cylinder gas requires it?
Puddle fluidity
1/4 inch to 1/2 inch
To prevent leakage - Carbon Dioxide (CO2)
Dry ice can form within the flow control openings and cause blockage of shielding gas

26. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
Generally not as accurate
Duty cycle
When the filler wire is in direct contract with the base metal

27. What are the 2 types of wire feeders available?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Gas metal arc welding
V groove or U groove
Constant- speed wire feeders and Voltage- sennsing wire feeders

28. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
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
Puddle fluidity
(DCEP) Direct Current Electrode Positive or Reverse polarity
If you dont know this check your phone

29. What is a typical flow rate of CO2 for short circuit transfer?
Cause flaking - which can clog the liner and contact tube
5.8 to 12.5 L/min
Duty cycle
Dry ice can form within the flow control openings and cause blockage of shielding gas

30. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
These terms are quite restrictive and often technically incorrect
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
AWS and CSA

31. Why is the term GMAW preferred over MIG or MAG?
Insufficient current to melt the wire off cleanly
These terms are quite restrictive and often technically incorrect
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
AWS and CSA

32. In the GMAW process what does amperage control?
Pressure vessels and the piping industry
Penetration and burn - off rate of the electrode
Reducing the gas source pressure to a constant working pressure
Guns

33. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Constant voltage (CV)
20 to 200 times per second
Flux cored wires

34. What does the wire feeder control?
Wire feed speed - Voltage control
Aluminum wire
Speed of the feed motor and - starting / stopping electrode feed
Dry ice can form within the flow control openings and cause blockage of shielding gas

35. What is the required arc voltage used for short circuit transfer?
Short- circuiting transfer - Globular transfer - Spray transfer
12 to 22 arc volts
Penetration and burn - off rate of the electrode
To prevent drawing of liquid CO2 (Carbon Dioxide)

36. What does voltage do in an electrical circuit?
The Arc voltage
Voltage is the force that overcomes resistance to allow amperage flow
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Higher 26 to 35 arc volts

37. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Short- circuiting transfer - Globular transfer - Spray transfer
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Generally not as accurate
Constant current (CC)

38. Why is a line heater required when using GMAW?
Wire feed speed - Voltage control
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
AWS and CSA

39. List the factors that determine the mode of metal transfer
DCEP (Direct Current Electrode Positive) Reverse Polarity
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
1/4 inch to 1/2 inch
The time rate of response for the current rise and fall

40. 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
Speed of the feed motor and - starting / stopping electrode feed
Dry ice can form within the flow control openings and cause blockage of shielding gas
Higher 26 to 35 arc volts

41. How are GMAW guns rated?
Puddle fluidity
By there current carrying capacity
SMAW - GTAW
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

42. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Insufficient current to melt the wire off cleanly
Gas metal arc welding
Wire feeds smoothly (yet will slip should a problem occur in the gun)

43. In the GMAW process what does voltage control?
Pressure vessels and the piping industry
1/4 inch to 1/2 inch
Gives arc voltage values to the control system of the feeder
Puddle fluidity

44. 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
The resistace to electrical current flow increases with it. Causing the electrode to heat
Short- circuiting transfer - Globular transfer - Spray transfer
Puddle fluidity

45. What is the key advantage of short circuiting transfer?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Constant voltage (CV)
Minimum distortion due to low heat input
Constant- speed wire feeders and Voltage- sennsing wire feeders

46. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
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%
(DCEP) Direct Current Electrode Positive or Reverse polarity
DCEP (Direct Current Electrode Positive) Reverse Polarity

47. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Duty cycle
(DCEP) Direct Current Electrode Positive or Reverse polarity
AWS and CSA

48. What is the effect of too much slope?
Spatter problems and poor weld appearance
Insufficient current to melt the wire off cleanly
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
If you dont know this check your phone

49. What is the maximum distance that hard wire can be successfully pushed?
Duty cycle
15 feet (4.5 meters)
DCEP (Direct Current Electrode Positive) Reverse Polarity
Gives arc voltage values to the control system of the feeder

50. Why is globular transfer generally avoided with GMAW?
These terms are quite restrictive and often technically incorrect
Generally not as accurate
Pressure - The rate of flow of a shielding gas
Spatter problems and poor weld appearance