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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 2 controls are found on a GMAW set- up?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
V groove or U groove
By there current carrying capacity
Wire feed speed - Voltage control

2. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Constant- speed wire feeders and Voltage- sennsing wire feeders
...
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
The time rate of response for the current rise and fall

3. What processes are constant current (CC) power sources designed to be used with?
85%
SMAW - GTAW
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Dry ice can form within the flow control openings and cause blockage of shielding gas

4. When is the metal transferred with short circuit transfer?
When the filler wire is in direct contract with the base metal
Penetration and burn - off rate of the electrode
AWS and CSA
DCEP (Direct Current Electrode Positive) Reverse Polarity

5. List the basic equipment requirements for the GMAW process
To prevent drawing of liquid CO2 (Carbon Dioxide)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Pressure vessels and the piping industry
Cause flaking - which can clog the liner and contact tube

6. What is another term for electrode holders for GMAW?
Insufficient current to melt the wire off cleanly
Guns
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Gas metal arc welding

7. What does the term GMAW identify?
Gas metal arc welding
Pressure vessels and the piping industry
Aluminum wire
SMAW - GTAW

8. What is the purpose of the shielding gas used in GMAW?
Constant voltage (CV)
15 feet (4.5 meters)
The negative side of a welding unit
Shielding the molten weld metal from atmospheric contamination

9. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Duty cycle
(DCEP) Direct Current Electrode Positive or Reverse polarity
The negative side of a welding unit
SMAW - GTAW

10. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
When the filler wire is in direct contract with the base metal
20 to 200 times per second
National Electrical Manufactures Association
Gives arc voltage values to the control system of the feeder

11. What is the purpose of a regulator and what does it indicate on its gauges?
Higher 26 to 35 arc volts
Short- circuiting transfer - Globular transfer - Spray transfer
Reducing the gas source pressure to a constant working pressure
Minimum distortion due to low heat input

12. Why is a line heater required when using GMAW?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Controls the rate of flow of a shielding gas to the gun nozzle
Dry ice can form within the flow control openings and cause blockage of shielding gas
Insufficient current to melt the wire off cleanly

13. List several industries that would use GMAW
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
3
Constant- speed wire feeders and Voltage- sennsing wire feeders
Pressure vessels and the piping industry

14. 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
Shielding the molten weld metal from atmospheric contamination
If you dont know this check your phone
12 to 22 arc volts

15. Why is the term GMAW preferred over MIG or MAG?
Higher 26 to 35 arc volts
The resistace to electrical current flow increases with it. Causing the electrode to heat
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

16. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
85%
If you dont know this check your phone
The negative side of a welding unit
By there current carrying capacity

17. A pull type drive system is usually used on what type of material?
Controls the rate of flow of a shielding gas to the gun nozzle
Aluminum 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
Dry ice can form within the flow control openings and cause blockage of shielding gas

18. What 2 organizations designate specifications for GMAW wires?
Generally not as accurate
Flux cored wires
AWS and CSA
Puddle fluidity

19. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
5.8 to 12.5 L/min
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
When the filler wire is in direct contract with the base metal

20. What controls amperage when using GMAW?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Pressure vessels and the piping industry
Pressure - The rate of flow of a shielding gas
Wire feed speed

21. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
20 to 200 times per second
Insufficient current to melt the wire off cleanly
When the filler wire is in direct contract with the base metal

22. 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
15 feet (4.5 meters)
To prevent leakage - Carbon Dioxide (CO2)
5.8 to 12.5 L/min

23. List 3 forms compressed gases may be supplied for welding
When the filler wire is in direct contract with the base metal
These terms are quite restrictive and often technically incorrect
12 to 22 arc volts
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

24. How are GMAW guns rated?
The negative side of a welding unit
By there current carrying capacity
V groove or U groove
National Electrical Manufactures Association

25. Regulators control_____________ flowmeters SHOW____________.
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
12 to 22 arc volts
The negative side of a welding unit
Pressure - The rate of flow of a shielding gas

26. 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
Spatter problems and poor weld appearance
Constant current (CC)
When the filler wire is in direct contract with the base metal

27. What is a typical flow rate of CO2 for short circuit transfer?
Welding process that joins metals by heating them with an electric arc
5.8 to 12.5 L/min
15 feet (4.5 meters)
12 to 22 arc volts

28. In the GMAW process what does voltage control?
Cause flaking - which can clog the liner and contact tube
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
National Electrical Manufactures Association

29. List the three methods of metal transfer with GMAW
Welding process that joins metals by heating them with an electric arc
Short- circuiting transfer - Globular transfer - Spray transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
SMAW - GTAW

30. What does inductance control?
Spatter problems and poor weld appearance
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
The time rate of response for the current rise and fall
If you dont know this check your phone

31. How many times per second does short circuiting take place?
National Electrical Manufactures Association
20 to 200 times per second
Insufficient current to melt the wire off cleanly
...

32. Why is globular transfer generally avoided with GMAW?
Minutes of elapsed time continually run (out of 10 minutes)
The time rate of response for the current rise and fall
Spatter problems and poor weld appearance
Puddle fluidity

33. What are the 2 types of wire feeders available?
To prevent leakage - Carbon Dioxide (CO2)
Gives arc voltage values to the control system of the feeder
Cause flaking - which can clog the liner and contact tube
Constant- speed wire feeders and Voltage- sennsing wire feeders

34. 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
Wire feed speed - Voltage control
Constant voltage (CV)
The time rate of response for the current rise and fall

35. What is the maximum distance that hard wire can be successfully pushed?
Short- circuiting transfer - Globular transfer - Spray transfer
(DCEP) Direct Current Electrode Positive or Reverse polarity
15 feet (4.5 meters)
By there current carrying capacity

36. What wire are knurled drive rolls most commonly used on?
Flux cored wires
Minimum distortion due to low heat input
To prevent leakage - Carbon Dioxide (CO2)
(DCEP) Direct Current Electrode Positive or Reverse polarity

37. What controls the wire speed on a voltage sensing wire feeder?
National Electrical Manufactures Association
Dry ice can form within the flow control openings and cause blockage of shielding gas
The Arc voltage
V groove or U groove

38. What power sources are used with the GMAW Process?
These terms are quite restrictive and often technically incorrect
Higher 26 to 35 arc volts
Motor driven generators - Transformer rectifiers - and Inverter designs
Flux cored wires

39. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Constant- speed wire feeders and Voltage- sennsing wire feeders
3
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
The time rate of response for the current rise and fall

40. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Pressure vessels and the piping industry
To limit the short circuiting current so that spatter is reduced

41. What type of power source is commonly used with a voltage sensing wire feeder?
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)
Motor driven generators - Transformer rectifiers - and Inverter designs
3

42. What is the recommended electrode stick- out for .035 solid wire?
Penetration and burn - off rate of the electrode
If you dont know this check your phone
Minimum distortion due to low heat input
1/4 inch to 1/2 inch

43. What does the abbreviation NEMA stand for?
These terms are quite restrictive and often technically incorrect
National Electrical Manufactures Association
If you dont know this check your phone
If you dont know this check your phone

44. List the factors that determine the mode of metal transfer
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Spatter problems and poor weld appearance
Constant current (CC)
Motor driven generators - Transformer rectifiers - and Inverter designs

45. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
National Electrical Manufactures Association
Aluminum wire
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

46. Why must CO2 cylinders be used in the vertical position?
Aluminum wire
If you dont know this check your phone
To prevent drawing of liquid CO2 (Carbon Dioxide)
Constant current (CC)

47. What is the main purpose of 'slope'?
Speed of the feed motor and - starting / stopping electrode feed
To limit the short circuiting current so that spatter is reduced
To prevent leakage - Carbon Dioxide (CO2)
The Arc voltage

48. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
Wire feed speed - Voltage control
These terms are quite restrictive and often technically incorrect
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

49. What is the effect of too much slope?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Insufficient current to melt the wire off cleanly
The Arc voltage
When the filler wire is in direct contract with the base metal

50. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Higher 26 to 35 arc volts
1/4 inch to 1/2 inch