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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. A pull type drive system is usually used on what type of material?
When the filler wire is in direct contract with the base metal
Dry ice can form within the flow control openings and cause blockage of shielding gas
Aluminum wire
15 feet (4.5 meters)

2. Regulators control_____________ flowmeters SHOW____________.
AWS and CSA
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Pressure - The rate of flow of a shielding gas
Wire feed speed

3. What are the 2 types of wire feeders available?
Welding process that joins metals by heating them with an electric arc
Constant- speed wire feeders and Voltage- sennsing wire feeders
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

4. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
Flux cored wires
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
3

5. 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
Cause flaking - which can clog the liner and contact tube
The resistace to electrical current flow increases with it. Causing the electrode to heat
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

6. What is the key advantage of short circuiting transfer?
85%
Shielding the molten weld metal from atmospheric contamination
Minutes of elapsed time continually run (out of 10 minutes)
Minimum distortion due to low heat input

7. Draw a typical volt amp curve for a machine that is designed for GMAW
If you dont know this check your phone
Shielding the molten weld metal from atmospheric contamination
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
The time rate of response for the current rise and fall

8. What output on the welding machine is used to rate the duty cycle?
Constant current (CC)
V groove or U groove
Minutes of elapsed time continually run (out of 10 minutes)
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?
By there current carrying capacity
The negative side of a welding unit
(DCEP) Direct Current Electrode Positive or Reverse polarity
Motor driven generators - Transformer rectifiers - and Inverter designs

10. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
The negative side of a welding unit
Dry ice can form within the flow control openings and cause blockage of shielding gas
Constant current (CC)
Cause flaking - which can clog the liner and contact tube

11. What controls the wire speed on a voltage sensing wire feeder?
Cause flaking - which can clog the liner and contact tube
The Arc voltage
To prevent leakage - Carbon Dioxide (CO2)
These terms are quite restrictive and often technically incorrect

12. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
...
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
85%
Shielding the molten weld metal from atmospheric contamination

13. What would be an indication that the drive roll pressure is adjusted correctly?
Puddle fluidity
Wire feeds smoothly (yet will slip should a problem occur in the gun)
If you dont know this check your phone
Dry ice can form within the flow control openings and cause blockage of shielding gas

14. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Penetration and burn - off rate of the electrode
...
15 feet (4.5 meters)
Duty cycle

15. Why is a fiber washer required and what cylinder gas requires it?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
The Arc voltage
To prevent leakage - Carbon Dioxide (CO2)

16. List the basic equipment requirements for the GMAW process
Wire feeds smoothly (yet will slip should a problem occur in the gun)
12 to 22 arc volts
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
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

17. Why is globular transfer generally avoided with GMAW?
Shielding the molten weld metal from atmospheric contamination
Dry ice can form within the flow control openings and cause blockage of shielding gas
The resistace to electrical current flow increases with it. Causing the electrode to heat
Spatter problems and poor weld appearance

18. List several industries that would use GMAW
Minimum distortion due to low heat input
By there current carrying capacity
Guns
Pressure vessels and the piping industry

19. List the factors that determine the mode of metal transfer
Minimum distortion due to low heat input
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
National Electrical Manufactures Association
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

20. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Higher 26 to 35 arc volts
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Gives arc voltage values to the control system of the feeder
Short- circuiting transfer - Globular transfer - Spray transfer

21. What is another term for electrode holders for GMAW?
Minimum distortion due to low heat input
Guns
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

22. What is the maximum distance that hard wire can be successfully pushed?
Generally not as accurate
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
15 feet (4.5 meters)
Insufficient current to melt the wire off cleanly

23. What is the main purpose of 'slope'?
Flux cored wires
Pressure - The rate of flow of a shielding gas
To limit the short circuiting current so that spatter is reduced
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

24. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Constant current (CC)
These terms are quite restrictive and often technically incorrect
If you dont know this check your phone

25. Why is a line heater required when using GMAW?
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
When the filler wire is in direct contract with the base metal

26. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
1/4 inch to 1/2 inch
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Constant current (CC)

27. What 2 controls are found on a GMAW set- up?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Higher 26 to 35 arc volts
5.8 to 12.5 L/min
Wire feed speed - Voltage control

28. What type of power source is commonly used with a voltage sensing wire feeder?
Aluminum wire
AWS and CSA
Controls the rate of flow of a shielding gas to the gun nozzle
Constant current (CC)

29. What power sources are used with the GMAW Process?
Dry ice can form within the flow control openings and cause blockage of shielding gas
The time rate of response for the current rise and fall
Motor driven generators - Transformer rectifiers - and Inverter designs
Puddle fluidity

30. What happens when the electrode extension is increased?
Constant current (CC)
To prevent leakage - Carbon Dioxide (CO2)
The resistace to electrical current flow increases with it. Causing the electrode to heat
85%

31. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
20 to 200 times per second
SMAW - GTAW
Wire feed speed - Voltage control

32. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Voltage is the force that overcomes resistance to allow amperage flow
...
Constant current (CC)

33. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
Gas metal arc welding
SMAW - GTAW
Welding process that joins metals by heating them with an electric arc

34. What does the abbreviation NEMA stand for?
1/4 inch to 1/2 inch
Insufficient current to melt the wire off cleanly
National Electrical Manufactures Association
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

35. What does inductance control?
The time rate of response for the current rise and fall
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
SMAW - GTAW
3

36. What does the wire feeder control?
The Arc voltage
Speed of the feed motor and - starting / stopping electrode feed
Penetration and burn - off rate of the electrode
Wire feeds smoothly (yet will slip should a problem occur in the gun)

37. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Flux cored wires
Welding process that joins metals by heating them with an electric arc
Higher 26 to 35 arc volts
3

38. Give a description of 'pinch effect'
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Dry ice can form within the flow control openings and cause blockage of shielding gas
The negative side of a welding unit
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

39. With straight polarity where is 2/3 of the arc energy?
Pressure - The rate of flow of a shielding gas
V groove or U groove
The negative side of a welding unit
Aluminum wire

40. What is a typical flow rate of CO2 for short circuit transfer?
When the filler wire is in direct contract with the base metal
5.8 to 12.5 L/min
Gas metal arc welding
V groove or U groove

41. List 3 forms compressed gases may be supplied for welding
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
National Electrical Manufactures Association
Minutes of elapsed time continually run (out of 10 minutes)
SMAW - GTAW

42. List the three methods of metal transfer with GMAW
Dry ice can form within the flow control openings and cause blockage of shielding gas
Wire feed speed
Short- circuiting transfer - Globular transfer - Spray transfer
1/4 inch to 1/2 inch

43. What is a solenoid valve and what actuates it?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Cause flaking - which can clog the liner and contact tube
Flux cored wires
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

44. What does a flowmeter do and what does it measure?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Gives arc voltage values to the control system of the feeder
5.8 to 12.5 L/min
Controls the rate of flow of a shielding gas to the gun nozzle

45. In the GMAW process what does amperage control?
AWS and CSA
Higher 26 to 35 arc volts
5.8 to 12.5 L/min
Penetration and burn - off rate of the electrode

46. Why is the term GMAW preferred over MIG or MAG?
When the filler wire is in direct contract with the base metal
Higher 26 to 35 arc volts
These terms are quite restrictive and often technically incorrect
12 to 22 arc volts

47. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
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
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

48. What current and polarity is generally used with GMAW?
These terms are quite restrictive and often technically incorrect
DCEP (Direct Current Electrode Positive) Reverse Polarity
(DCEP) Direct Current Electrode Positive or Reverse polarity
To prevent drawing of liquid CO2 (Carbon Dioxide)

49. How many times per second does short circuiting take place?
AWS and CSA
20 to 200 times per second
These terms are quite restrictive and often technically incorrect
15 feet (4.5 meters)

50. What is the recommended electrode stick- out for .035 solid wire?
By there current carrying capacity
1/4 inch to 1/2 inch
V groove or U groove
Constant voltage (CV)