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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. Draw a typical volt amp curve for a machine that is designed for GMAW
If you dont know this check your phone
Wire feeds smoothly (yet will slip should a problem occur in the gun)
12 to 22 arc volts
Generally not as accurate

2. What type of power source is commonly used with a voltage sensing wire feeder?
Voltage is the force that overcomes resistance to allow amperage flow
Constant current (CC)
To prevent leakage - Carbon Dioxide (CO2)
Controls the rate of flow of a shielding gas to the gun nozzle

3. What processes are constant current (CC) power sources designed to be used with?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
By there current carrying capacity
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
SMAW - GTAW

4. Why is a line heater required when using GMAW?
Duty cycle
Dry ice can form within the flow control openings and cause blockage of shielding gas
By there current carrying capacity
...

5. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
3
Duty cycle

6. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
5.8 to 12.5 L/min
85%
1/4 inch to 1/2 inch

7. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Constant- speed wire feeders and Voltage- sennsing wire feeders
SMAW - 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
Cause flaking - which can clog the liner and contact tube

8. A pull type drive system is usually used on what type of material?
Welding process that joins metals by heating them with an electric arc
Aluminum wire
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Constant- speed wire feeders and Voltage- sennsing wire feeders

9. What current and polarity is generally used with GMAW?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
DCEP (Direct Current Electrode Positive) Reverse Polarity
To prevent leakage - Carbon Dioxide (CO2)
National Electrical Manufactures Association

10. What is a typical flow rate of CO2 for short circuit transfer?
5.8 to 12.5 L/min
Controls the rate of flow of a shielding gas to the gun nozzle
3
Speed of the feed motor and - starting / stopping electrode feed

11. What would be an indication that the drive roll pressure is adjusted correctly?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
5.8 to 12.5 L/min
Gives arc voltage values to the control system of the feeder
Gas metal arc welding

12. List the factors that determine the mode of metal transfer
Generally not as accurate
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
...
85%

13. What 2 controls are found on a GMAW set- up?
12 to 22 arc volts
AWS and CSA
Wire feed speed - Voltage control
Pressure vessels and the piping industry

14. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
Constant voltage (CV)
The Arc voltage
15 feet (4.5 meters)

15. A 10 minute cycle of welding time vs cooling time a given machine can handle.
3
Pressure vessels and the piping industry
Duty cycle
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

16. How many times per second does short circuiting take place?
Short- circuiting transfer - Globular transfer - Spray transfer
20 to 200 times per second
The time rate of response for the current rise and fall
5.8 to 12.5 L/min

17. Why must CO2 cylinders be used in the vertical position?
Constant voltage (CV)
To prevent drawing of liquid CO2 (Carbon Dioxide)
To prevent leakage - Carbon Dioxide (CO2)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

18. When is the metal transferred with short circuit transfer?
The Arc voltage
When the filler wire is in direct contract with the base metal
If you dont know this check your phone
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

19. What is the maximum distance that hard wire can be successfully pushed?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
1/4 inch to 1/2 inch
15 feet (4.5 meters)

20. What does the abbreviation NEMA stand for?
Aluminum wire
SMAW - GTAW
National Electrical Manufactures Association
Wire feeds smoothly (yet will slip should a problem occur in the gun)

21. With straight polarity where is 2/3 of the arc energy?
Minimum distortion due to low heat input
Duty cycle
1/4 inch to 1/2 inch
The negative side of a welding unit

22. What is the key advantage of short circuiting transfer?
AWS and CSA
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Generally not as accurate
Minimum distortion due to low heat input

23. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
Flux cored wires
When the filler wire is in direct contract with the base metal
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

24. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
...
12 to 22 arc volts
Wire feed speed
Minimum distortion due to low heat input

25. What are the 2 types of wire feeders available?
The Arc voltage
Spatter problems and poor weld appearance
Constant- speed wire feeders and Voltage- sennsing wire feeders
These terms are quite restrictive and often technically incorrect

26. List 3 wire drive systems and give a short description of each
Pressure - The rate of flow of a shielding gas
15 feet (4.5 meters)
Gives arc voltage values to the control system of the feeder
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

27. What is another term for electrode holders for GMAW?
Guns
Short- circuiting transfer - Globular transfer - Spray transfer
Insufficient current to melt the wire off cleanly
3

28. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
Motor driven generators - Transformer rectifiers - and Inverter designs
Reducing the gas source pressure to a constant working pressure
Minutes of elapsed time continually run (out of 10 minutes)

29. What is the purpose of a regulator and what does it indicate on its gauges?
Spatter problems and poor weld appearance
Reducing the gas source pressure to a constant working pressure
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Pressure vessels and the piping industry

30. What type of power source is used with a constant speed wire feeder?
The Arc voltage
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Wire feed speed - Voltage control
Constant voltage (CV)

31. In the GMAW process what does voltage control?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Minutes of elapsed time continually run (out of 10 minutes)
Puddle fluidity
Constant voltage (CV)

32. Regulators control_____________ flowmeters SHOW____________.
To prevent drawing of liquid CO2 (Carbon Dioxide)
Pressure - The rate of flow of a shielding gas
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
5.8 to 12.5 L/min

33. In the GMAW process what does amperage control?
...
Penetration and burn - off rate of the electrode
The time rate of response for the current rise and fall
Pressure vessels and the piping industry

34. List several industries that would use GMAW
Pressure vessels and the piping industry
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

35. What effect does increasing and decreasing the inductance have on the weld?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Reducing the gas source pressure to a constant working pressure
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Gives arc voltage values to the control system of the feeder

36. What is a solenoid valve and what actuates it?
20 to 200 times per second
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
The negative side of a welding unit
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

37. What does voltage do in an electrical circuit?
Puddle fluidity
These terms are quite restrictive and often technically incorrect
Voltage is the force that overcomes resistance to allow amperage flow
DCEP (Direct Current Electrode Positive) Reverse Polarity

38. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Speed of the feed motor and - starting / stopping electrode feed
Motor driven generators - Transformer rectifiers - and Inverter designs
Minimum distortion due to low heat input
Gives arc voltage values to the control system of the feeder

39. What is the recommended electrode stick- out for .035 solid wire?
Controls the rate of flow of a shielding gas to the gun nozzle
Generally not as accurate
When the filler wire is in direct contract with the base metal
1/4 inch to 1/2 inch

40. What is the required arc voltage used for short circuit transfer?
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)
12 to 22 arc volts
When the filler wire is in direct contract with the base metal

41. Give a description of 'pinch effect'
The resistace to electrical current flow increases with it. Causing the electrode to heat
(DCEP) Direct Current Electrode Positive or Reverse polarity
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

42. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
15 feet (4.5 meters)
These terms are quite restrictive and often technically incorrect
If you dont know this check your phone
V groove or U groove

43. What is the effect of too much slope?
AWS and CSA
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Insufficient current to melt the wire off cleanly
Wire feeds smoothly (yet will slip should a problem occur in the gun)

44. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Spatter problems and poor weld appearance
Cause flaking - which can clog the liner and contact tube
By there current carrying capacity

45. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
National Electrical Manufactures Association
5.8 to 12.5 L/min
Motor driven generators - Transformer rectifiers - and Inverter designs

46. What does inductance control?
Controls the rate of flow of a shielding gas to the gun nozzle
If you dont know this check your phone
The time rate of response for the current rise and fall
Gives arc voltage values to the control system of the feeder

47. What 2 organizations designate specifications for GMAW wires?
To prevent leakage - Carbon Dioxide (CO2)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Gas metal arc welding
AWS and CSA

48. Why is the term GMAW preferred over MIG or MAG?
AWS and CSA
These terms are quite restrictive and often technically incorrect
5.8 to 12.5 L/min
3

49. What is an advantage of pulsed arc transfer with GMAW?
15 feet (4.5 meters)
To limit the short circuiting current so that spatter is reduced
Generally not as accurate
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

50. What does the wire feeder control?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Speed of the feed motor and - starting / stopping electrode feed
20 to 200 times per second
Spatter problems and poor weld appearance