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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 wire are knurled drive rolls most commonly used on?
AWS and CSA
Pressure vessels and the piping industry
Shielding the molten weld metal from atmospheric contamination
Flux cored wires

2. List the basic equipment requirements for the GMAW process
Shielding the molten weld metal from atmospheric contamination
Flux cored wires
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Voltage is the force that overcomes resistance to allow amperage flow

3. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Minimum distortion due to low heat input
85%
1/4 inch to 1/2 inch
Constant voltage (CV)

4. In the GMAW process what does amperage control?
Gives arc voltage values to the control system of the feeder
(DCEP) Direct Current Electrode Positive or Reverse polarity
Penetration and burn - off rate of the electrode
Guns

5. Give a brief description of the GMAW process
12 to 22 arc volts
Welding process that joins metals by heating them with an electric arc
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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

6. 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
Pressure vessels and the piping industry
AWS and CSA
Pressure - The rate of flow of a shielding gas

7. What 2 controls are found on a GMAW set- up?
Generally not as accurate
Wire feed speed - Voltage control
Puddle fluidity
Insufficient current to melt the wire off cleanly

8. What is an advantage of pulsed arc transfer with GMAW?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
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Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Flux cored wires

9. What 2 organizations designate specifications for GMAW wires?
AWS and CSA
Guns
By there current carrying capacity
Pressure - The rate of flow of a shielding gas

10. List 3 forms compressed gases may be supplied for welding
Gas metal arc welding
3
Constant voltage (CV)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

11. What is the preferred drive roll design for solid wires?
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
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
V groove or U groove

12. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Insufficient current to melt the wire off cleanly
AWS and CSA
Shielding the molten weld metal from atmospheric contamination

13. What is the main purpose of 'slope'?
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
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To limit the short circuiting current so that spatter is reduced

14. Regulators control_____________ flowmeters SHOW____________.
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Wire feeds smoothly (yet will slip should a problem occur in the gun)
Pressure - The rate of flow of a shielding gas
Generally not as accurate

15. What controls the wire speed on a voltage sensing wire feeder?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Cause flaking - which can clog the liner and contact tube
The Arc voltage
National Electrical Manufactures Association

16. List the factors that determine the mode of metal transfer
Pressure - The rate of flow of a shielding gas
Speed of the feed motor and - starting / stopping electrode feed
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
5.8 to 12.5 L/min

17. What would be an indication that the drive roll pressure is adjusted correctly?
To prevent drawing of liquid CO2 (Carbon Dioxide)
The negative side of a welding unit
Wire feeds smoothly (yet will slip should a problem occur in the gun)
The time rate of response for the current rise and fall

18. What output on the welding machine is used to rate the duty cycle?
Insufficient current to melt the wire off cleanly
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Motor driven generators - Transformer rectifiers - and Inverter designs
Minutes of elapsed time continually run (out of 10 minutes)

19. What is the required arc voltage used for short circuit transfer?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Flux cored wires
Generally not as accurate
12 to 22 arc volts

20. When is the metal transferred with short circuit transfer?
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These terms are quite restrictive and often technically incorrect
To prevent leakage - Carbon Dioxide (CO2)
When the filler wire is in direct contract with the base metal

21. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
If you dont know this check your phone
To limit the short circuiting current so that spatter is reduced
1/4 inch to 1/2 inch
The resistace to electrical current flow increases with it. Causing the electrode to heat

22. What does inductance control?
85%
Minutes of elapsed time continually run (out of 10 minutes)
Minimum distortion due to low heat input
The time rate of response for the current rise and fall

23. What is a typical flow rate of CO2 for short circuit transfer?
Minimum distortion due to low heat input
5.8 to 12.5 L/min
Welding process that joins metals by heating them with an electric arc
SMAW - GTAW

24. What type of power source is used with a constant speed wire feeder?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Constant voltage (CV)
Aluminum wire
5.8 to 12.5 L/min

25. How are GMAW guns rated?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
SMAW - GTAW
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

26. What are the 2 types of wire feeders available?
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
Welding process that joins metals by heating them with an electric arc
Spatter problems and poor weld appearance

27. 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
3
5.8 to 12.5 L/min
AWS and CSA

28. Why is globular transfer generally avoided with GMAW?
Minutes of elapsed time continually run (out of 10 minutes)
Minimum distortion due to low heat input
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
Spatter problems and poor weld appearance

29. With straight polarity where is 2/3 of the arc energy?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
The negative side of a welding unit

30. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Cause flaking - which can clog the liner and contact tube
The Arc voltage
If you dont know this check your phone

31. How many times per second does short circuiting take place?
The negative side of a welding unit
Higher 26 to 35 arc volts
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
20 to 200 times per second

32. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
...
Puddle fluidity
(DCEP) Direct Current Electrode Positive or Reverse polarity
DCEP (Direct Current Electrode Positive) Reverse Polarity

33. What controls amperage when using GMAW?
Wire feed speed
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Constant- speed wire feeders and Voltage- sennsing wire feeders
Voltage is the force that overcomes resistance to allow amperage flow

34. Why must CO2 cylinders be used in the vertical position?
85%
To prevent drawing of liquid CO2 (Carbon Dioxide)
Aluminum wire
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

35. List 3 wire drive systems and give a short description of each
Speed of the feed motor and - starting / stopping electrode feed
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
Penetration and burn - off rate of the electrode
Generally not as accurate

36. What does the abbreviation NEMA stand for?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
National Electrical Manufactures Association
V groove or U groove
By there current carrying capacity

37. What does a flowmeter do and what does it measure?
Controls the rate of flow of a shielding gas to the gun nozzle
The time rate of response for the current rise and fall
20 to 200 times per second
The negative side of a welding unit

38. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Cause flaking - which can clog the liner and contact tube
Generally not as accurate
Higher 26 to 35 arc volts
Constant voltage (CV)

39. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Guns
To prevent drawing of liquid CO2 (Carbon Dioxide)
Spatter problems and poor weld appearance
Duty cycle

40. What is a solenoid valve and what actuates it?
When the filler wire is in direct contract with the base metal
Flux cored wires
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Motor driven generators - Transformer rectifiers - and Inverter designs

41. What type of power source is commonly used with a voltage sensing wire feeder?
Constant current (CC)
85%
Voltage is the force that overcomes resistance to allow amperage flow
Spatter problems and poor weld appearance

42. List several industries that would use GMAW
These terms are quite restrictive and often technically incorrect
Pressure vessels and the piping industry
Constant voltage (CV)
15 feet (4.5 meters)

43. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Higher 26 to 35 arc volts
...
Aluminum wire
AWS and CSA

44. What effect does increasing and decreasing the inductance have on the weld?
Minimum distortion due to low heat input
3
The time rate of response for the current rise and fall
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

45. What is the maximum distance that hard wire can be successfully pushed?
Minimum distortion due to low heat input
DCEP (Direct Current Electrode Positive) Reverse Polarity
To prevent drawing of liquid CO2 (Carbon Dioxide)
15 feet (4.5 meters)

46. Why is a fiber washer required and what cylinder gas requires it?
Puddle fluidity
To prevent leakage - Carbon Dioxide (CO2)
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

47. What does the wire feeder control?
Speed of the feed motor and - starting / stopping electrode feed
These terms are quite restrictive and often technically incorrect
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Dry ice can form within the flow control openings and cause blockage of shielding gas

48. Why is the term GMAW preferred over MIG or MAG?
...
Puddle fluidity
Higher 26 to 35 arc volts
These terms are quite restrictive and often technically incorrect

49. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
The time rate of response for the current rise and fall
Shielding the molten weld metal from atmospheric contamination
SMAW - GTAW

50. What processes are constant current (CC) power sources designed to be used with?
These terms are quite restrictive and often technically incorrect
DCEP (Direct Current Electrode Positive) Reverse Polarity
Wire feed speed - Voltage control
SMAW - GTAW