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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 organizations designate specifications for GMAW wires?
Welding process that joins metals by heating them with an electric arc
AWS and CSA
Higher 26 to 35 arc volts
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

2. Why must CO2 cylinders be used in the vertical position?
Wire feed speed
To prevent drawing of liquid CO2 (Carbon Dioxide)
The Arc voltage
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

3. A pull type drive system is usually used on what type of material?
V groove or U groove
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
Aluminum wire

4. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Pressure vessels and the piping industry
3
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
If you dont know this check your phone

5. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
Gas metal arc welding
Wire feed speed
Controls the rate of flow of a shielding gas to the gun nozzle

6. List the factors that determine the mode of metal transfer
Flux cored wires
Pressure - The rate of flow of a shielding gas
Wire feed speed - Voltage control
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

7. What does the abbreviation NEMA stand for?
Higher 26 to 35 arc volts
Constant- speed wire feeders and Voltage- sennsing wire feeders
National Electrical Manufactures Association
85%

8. What output on the welding machine is used to rate the duty cycle?
Minutes of elapsed time continually run (out of 10 minutes)
Wire feed speed
Shielding the molten weld metal from atmospheric contamination
V groove or U groove

9. What is an advantage of pulsed arc transfer with GMAW?
National Electrical Manufactures Association
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
The negative side of a welding unit
Wire feeds smoothly (yet will slip should a problem occur in the gun)

10. What is the disadvantage of the gauge preset type of regulator/flowmeter?
The time rate of response for the current rise and fall
Constant voltage (CV)
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Generally not as accurate

11. List the basic equipment requirements for the GMAW process
Reducing the gas source pressure to a constant working pressure
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
When the filler wire is in direct contract with the base metal
20 to 200 times per second

12. 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
The resistace to electrical current flow increases with it. Causing the electrode to heat
15 feet (4.5 meters)
Gives arc voltage values to the control system of the feeder

13. What controls the wire speed on a voltage sensing wire feeder?
Constant- speed wire feeders and Voltage- sennsing wire feeders
The Arc voltage
National Electrical Manufactures Association
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

14. How many times per second does short circuiting take place?
20 to 200 times per second
Gives arc voltage values to the control system of the feeder
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
The Arc voltage

15. Why is a line heater required when using GMAW?
Spatter problems and poor weld appearance
Wire feed speed - Voltage control
Wire feed speed
Dry ice can form within the flow control openings and cause blockage of shielding gas

16. What does voltage do in an electrical circuit?
These terms are quite restrictive and often technically incorrect
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Voltage is the force that overcomes resistance to allow amperage flow
Duty cycle

17. What is the effect of too much slope?
Gives arc voltage values to the control system of the feeder
Spatter problems and poor weld appearance
Insufficient current to melt the wire off cleanly
5.8 to 12.5 L/min

18. What 2 controls are found on a GMAW set- up?
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Wire feed speed - Voltage control
By there current carrying capacity
3

19. Draw a typical volt amp curve for a machine that is designed for GMAW
(DCEP) Direct Current Electrode Positive or Reverse polarity
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Speed of the feed motor and - starting / stopping electrode feed
Aluminum wire

20. List 3 wire drive systems and give a short description of each
Welding process that joins metals by heating them with an electric arc
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
SMAW - GTAW

21. What type of power source is commonly used with a voltage sensing wire feeder?
Aluminum wire
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Insufficient current to melt the wire off cleanly
Constant current (CC)

22. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
Gas metal arc welding
Minimum distortion due to low heat input
DCEP (Direct Current Electrode Positive) Reverse Polarity

23. Regulators control_____________ flowmeters SHOW____________.
15 feet (4.5 meters)
AWS and CSA
Pressure - The rate of flow of a shielding gas
Gas metal arc welding

24. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Motor driven generators - Transformer rectifiers - and Inverter designs
20 to 200 times per second
The resistace to electrical current flow increases with it. Causing the electrode to heat
If you dont know this check your phone

25. What power sources are used with the GMAW Process?
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Speed of the feed motor and - starting / stopping electrode feed
Motor driven generators - Transformer rectifiers - and Inverter designs
Gives arc voltage values to the control system of the feeder

26. What does the wire feeder control?
The time rate of response for the current rise and fall
If you dont know this check your phone
Speed of the feed motor and - starting / stopping electrode feed
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

27. What does the term GMAW identify?
Generally not as accurate
Gas metal arc welding
V groove or U groove
Guns

28. What is the recommended electrode stick- out for .035 solid wire?
Penetration and burn - off rate of the electrode
1/4 inch to 1/2 inch
SMAW - GTAW
When the filler wire is in direct contract with the base metal

29. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
5.8 to 12.5 L/min
Welding process that joins metals by heating them with an electric arc
To prevent leakage - Carbon Dioxide (CO2)

30. What would be an indication that the drive roll pressure is adjusted correctly?
Speed of the feed motor and - starting / stopping electrode feed
Penetration and burn - off rate of the electrode
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 feeds smoothly (yet will slip should a problem occur in the gun)

31. What is a typical flow rate of CO2 for short circuit transfer?
Puddle fluidity
Insufficient current to melt the wire off cleanly
V groove or U groove
5.8 to 12.5 L/min

32. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
V groove or U groove
...
To prevent drawing of liquid CO2 (Carbon Dioxide)
3

33. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
V groove or U groove
85%
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
National Electrical Manufactures Association

34. What is the main purpose of 'slope'?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
To limit the short circuiting current so that spatter is reduced
Minimum distortion due to low heat input
Shielding the molten weld metal from atmospheric contamination

35. List the three methods of metal transfer with GMAW
Penetration and burn - off rate of the electrode
Short- circuiting transfer - Globular transfer - Spray transfer
15 feet (4.5 meters)
The time rate of response for the current rise and fall

36. What is the required arc voltage used for short circuit transfer?
If you dont know this check your phone
Voltage is the force that overcomes resistance to allow amperage flow
12 to 22 arc volts
Flux cored wires

37. What controls amperage when using GMAW?
The negative side of a welding unit
Constant- speed wire feeders and Voltage- sennsing wire feeders
Wire feed speed
National Electrical Manufactures Association

38. What happens when the electrode extension is increased?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
AWS and CSA
The resistace to electrical current flow increases with it. Causing the electrode to heat
Puddle fluidity

39. What processes are constant current (CC) power sources designed to be used with?
These terms are quite restrictive and often technically incorrect
Flux cored wires
SMAW - GTAW
National Electrical Manufactures Association

40. List 3 forms compressed gases may be supplied for welding
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Welding process that joins metals by heating them with an electric arc
To limit the short circuiting current so that spatter is reduced
Pressure vessels and the piping industry

41. What is the purpose of a regulator and what does it indicate on its gauges?
Reducing the gas source pressure to a constant working pressure
Welding process that joins metals by heating them with an electric arc
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Minutes of elapsed time continually run (out of 10 minutes)

42. What effect does increasing and decreasing the inductance have on the weld?
Motor driven generators - Transformer rectifiers - and Inverter designs
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
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

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

44. In the GMAW process what does voltage control?
1/4 inch to 1/2 inch
Duty cycle
Puddle fluidity
Guns

45. What is a solenoid valve and what actuates it?
To limit the short circuiting current so that spatter is reduced
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Gas metal arc welding

46. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
The negative side of a welding unit
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
To limit the short circuiting current so that spatter is reduced

47. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
85%
Cause flaking - which can clog the liner and contact tube
Speed of the feed motor and - starting / stopping electrode feed
Minutes of elapsed time continually run (out of 10 minutes)

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

49. When is the metal transferred with short circuit transfer?
To prevent leakage - Carbon Dioxide (CO2)
Pressure - The rate of flow of a shielding gas
When the filler wire is in direct contract with the base metal
National Electrical Manufactures Association

50. What type of power source is used with a constant speed wire feeder?
20 to 200 times per second
Constant voltage (CV)
If you dont know this check your phone
Spatter problems and poor weld appearance