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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?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Motor driven generators - Transformer rectifiers - and Inverter designs
Wire feed speed - Voltage control
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2. In the GMAW process what does voltage control?
Welding process that joins metals by heating them with an electric arc
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Puddle fluidity

3. Give a brief description of the GMAW process
Shielding the molten weld metal from atmospheric contamination
Welding process that joins metals by heating them with an electric arc
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Pressure - The rate of flow of a shielding gas

4. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
These terms are quite restrictive and often technically incorrect
Constant current (CC)
SMAW - GTAW

5. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Constant- speed wire feeders and Voltage- sennsing wire feeders
To prevent leakage - Carbon Dioxide (CO2)
SMAW - GTAW
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6. What controls the wire speed on a voltage sensing wire feeder?
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
12 to 22 arc volts
The Arc voltage

7. What current and polarity is generally used with GMAW?
Welding process that joins metals by heating them with an electric arc
Aluminum wire
Motor driven generators - Transformer rectifiers - and Inverter designs
DCEP (Direct Current Electrode Positive) Reverse Polarity

8. Why is a line heater required when using GMAW?
85%
Speed of the feed motor and - starting / stopping electrode feed
1/4 inch to 1/2 inch
Dry ice can form within the flow control openings and cause blockage of shielding gas

9. What is the recommended electrode stick- out for .035 solid wire?
Pressure vessels and the piping industry
1/4 inch to 1/2 inch
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Spatter problems and poor weld appearance

10. What is the purpose of a regulator and what does it indicate on its gauges?
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Gives arc voltage values to the control system of the feeder
(DCEP) Direct Current Electrode Positive or Reverse polarity
Reducing the gas source pressure to a constant working pressure

11. With straight polarity where is 2/3 of the arc energy?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Constant voltage (CV)
Minimum distortion due to low heat input
The negative side of a welding unit

12. List the basic equipment requirements for the GMAW process
85%
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Wire feed speed - Voltage control
15 feet (4.5 meters)

13. A 10 minute cycle of welding time vs cooling time a given machine can handle.
20 to 200 times per second
Voltage is the force that overcomes resistance to allow amperage flow
Duty cycle
Speed of the feed motor and - starting / stopping electrode feed

14. Why is the term GMAW preferred over MIG or MAG?
...
National Electrical Manufactures Association
These terms are quite restrictive and often technically incorrect
20 to 200 times per second

15. What does the wire feeder control?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Speed of the feed motor and - starting / stopping electrode feed
Minimum distortion due to low heat input
Pressure vessels and the piping industry

16. What output on the welding machine is used to rate the duty cycle?
Flux cored wires
Minutes of elapsed time continually run (out of 10 minutes)
Aluminum wire
Constant- speed wire feeders and Voltage- sennsing wire feeders

17. How are GMAW guns rated?
Controls the rate of flow of a shielding gas to the gun nozzle
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Duty cycle
By there current carrying capacity

18. What is a typical flow rate of CO2 for short circuit transfer?
Pressure - The rate of flow of a shielding gas
Constant voltage (CV)
5.8 to 12.5 L/min
Voltage is the force that overcomes resistance to allow amperage flow

19. What is another term for electrode holders for GMAW?
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These terms are quite restrictive and often technically incorrect
Voltage is the force that overcomes resistance to allow amperage flow
Guns

20. List several industries that would use GMAW
Controls the rate of flow of a shielding gas to the gun nozzle
These terms are quite restrictive and often technically incorrect
Pressure vessels and the piping industry
National Electrical Manufactures Association

21. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
To prevent drawing of liquid CO2 (Carbon Dioxide)
12 to 22 arc volts
(DCEP) Direct Current Electrode Positive or Reverse polarity

22. What happens when the electrode extension is increased?
Penetration and burn - off rate of the electrode
The resistace to electrical current flow increases with it. Causing the electrode to heat
Guns
Higher 26 to 35 arc volts

23. What does the abbreviation NEMA stand for?
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
Voltage is the force that overcomes resistance to allow amperage flow
National Electrical Manufactures Association

24. What does a flowmeter do and what does it measure?
Controls the rate of flow of a shielding gas to the gun nozzle
By there current carrying capacity
Reducing the gas source pressure to a constant working pressure
3

25. What processes are constant current (CC) power sources designed to be used with?
Flux cored wires
Voltage is the force that overcomes resistance to allow amperage flow
SMAW - GTAW
If you dont know this check your phone

26. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Cause flaking - which can clog the liner and contact tube
The negative side of a welding unit
National Electrical Manufactures Association

27. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
Spatter problems and poor weld appearance
To limit the short circuiting current so that spatter is reduced
1/4 inch to 1/2 inch

28. 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
The Arc voltage
Wire feeds smoothly (yet will slip should a problem occur in the gun)

29. What is a solenoid valve and what actuates it?
Wire feed speed - Voltage control
Controls the rate of flow of a shielding gas to the gun nozzle
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Cause flaking - which can clog the liner and contact tube

30. Why must CO2 cylinders be used in the vertical position?
...
Gas metal arc welding
To prevent drawing of liquid CO2 (Carbon Dioxide)
Generally not as accurate

31. What is the required arc voltage used for short circuit transfer?
Voltage is the force that overcomes resistance to allow amperage flow
Wire feed speed
Generally not as accurate
12 to 22 arc volts

32. Draw a typical volt amp curve for a machine that is designed for GMAW
Insufficient current to melt the wire off cleanly
If you dont know this check your phone
By there current carrying capacity
These terms are quite restrictive and often technically incorrect

33. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Generally not as accurate
...
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
These terms are quite restrictive and often technically incorrect

34. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Guns
(DCEP) Direct Current Electrode Positive or Reverse polarity
When the filler wire is in direct contract with the base metal
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

35. What type of power source is commonly used with a voltage sensing wire feeder?
V groove or U groove
5.8 to 12.5 L/min
SMAW - GTAW
Constant current (CC)

36. What would be an indication that the drive roll pressure is adjusted correctly?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Wire feeds smoothly (yet will slip should a problem occur in the gun)
When the filler wire is in direct contract with the base metal
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

37. List the factors that determine the mode of metal transfer
V groove or U groove
Higher 26 to 35 arc volts
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

38. A pull type drive system is usually used on what type of material?
Constant voltage (CV)
Aluminum wire
The Arc voltage
5.8 to 12.5 L/min

39. What controls amperage when using GMAW?
20 to 200 times per second
Pressure vessels and the piping industry
Voltage is the force that overcomes resistance to allow amperage flow
Wire feed speed

40. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Constant voltage (CV)
85%
Minutes of elapsed time continually run (out of 10 minutes)
Duty cycle

41. What is the key advantage of short circuiting transfer?
The negative side of a welding unit
Minimum distortion due to low heat input
SMAW - GTAW
DCEP (Direct Current Electrode Positive) Reverse Polarity

42. What wire are knurled drive rolls most commonly used on?
85%
Dry ice can form within the flow control openings and cause blockage of shielding gas
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Flux cored wires

43. List 3 forms compressed gases may be supplied for welding
...
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
By there current carrying capacity
Gives arc voltage values to the control system of the feeder

44. What does the term GMAW identify?
By there current carrying capacity
Constant voltage (CV)
Gas metal arc welding
12 to 22 arc volts

45. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
Cause flaking - which can clog the liner and contact tube
15 feet (4.5 meters)
If you dont know this check your phone

46. What is the main purpose of 'slope'?
These terms are quite restrictive and often technically incorrect
To limit the short circuiting current so that spatter is reduced
By there current carrying capacity
If you dont know this check your phone

47. Regulators control_____________ flowmeters SHOW____________.
Pressure - The rate of flow of a shielding gas
85%
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Constant voltage (CV)

48. What 2 organizations designate specifications for GMAW wires?
The negative side of a welding unit
Guns
Constant voltage (CV)
AWS and CSA

49. What is the preferred drive roll design for solid wires?
Welding process that joins metals by heating them with an electric arc
V groove or U groove
Speed of the feed motor and - starting / stopping electrode feed
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

50. What is an advantage of pulsed arc transfer with GMAW?
Cause flaking - which can clog the liner and contact tube
Gives arc voltage values to the control system of the feeder
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Minimum distortion due to low heat input