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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 term is used to describe when the workpiece is hooked to the negative pole on the power source?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Reducing the gas source pressure to a constant working pressure
Wire feeds smoothly (yet will slip should a problem occur in the gun)
85%

2. Draw a typical volt amp curve for a machine that is designed for GMAW
Insufficient current to melt the wire off cleanly
Motor driven generators - Transformer rectifiers - and Inverter designs
If you dont know this check your phone
The negative side of a welding unit

3. What 2 controls are found on a GMAW set- up?
Constant current (CC)
...
The time rate of response for the current rise and fall
Wire feed speed - Voltage control

4. What 2 organizations designate specifications for GMAW wires?
DCEP (Direct Current Electrode Positive) Reverse Polarity
AWS and CSA
Short- circuiting transfer - Globular transfer - Spray transfer
Aluminum wire

5. What current and polarity is generally used with GMAW?
When the filler wire is in direct contract with the base metal
20 to 200 times per second
DCEP (Direct Current Electrode Positive) Reverse Polarity
Cause flaking - which can clog the liner and contact tube

6. What is the purpose of the shielding gas used in GMAW?
These terms are quite restrictive and often technically incorrect
Shielding the molten weld metal from atmospheric contamination
Pressure vessels and the piping industry
Gives arc voltage values to the control system of the feeder

7. With straight polarity where is 2/3 of the arc energy?
...
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The negative side of a welding unit
Insufficient current to melt the wire off cleanly

8. List several industries that would use GMAW
Dry ice can form within the flow control openings and cause blockage of shielding gas
Duty cycle
The negative side of a welding unit
Pressure vessels and the piping industry

9. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
85%
Constant- speed wire feeders and Voltage- sennsing wire feeders
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Higher 26 to 35 arc volts

10. What controls amperage when using GMAW?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Wire feed speed
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Puddle fluidity

11. What does the term GMAW identify?
Penetration and burn - off rate of the electrode
Puddle fluidity
Gas metal arc welding
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

12. What power sources are used with the GMAW Process?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Motor driven generators - Transformer rectifiers - and Inverter designs
The resistace to electrical current flow increases with it. Causing the electrode to heat
Puddle fluidity

13. Why is a fiber washer required and what cylinder gas requires it?
AWS and CSA
By there current carrying capacity
To prevent leakage - Carbon Dioxide (CO2)
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

14. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
20 to 200 times per second
Gives arc voltage values to the control system of the feeder
Spatter problems and poor weld appearance
Flux cored wires

15. What output on the welding machine is used to rate the duty cycle?
Pressure - The rate of flow of a shielding gas
The time rate of response for the current rise and fall
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
Minutes of elapsed time continually run (out of 10 minutes)

16. What does the abbreviation NEMA stand for?
Reducing the gas source pressure to a constant working pressure
V groove or U groove
National Electrical Manufactures Association
Minimum distortion due to low heat input

17. Regulators control_____________ flowmeters SHOW____________.
The Arc voltage
Higher 26 to 35 arc volts
Pressure - The rate of flow of a shielding gas
SMAW - GTAW

18. What does the wire feeder control?
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
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Speed of the feed motor and - starting / stopping electrode feed

19. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Minutes of elapsed time continually run (out of 10 minutes)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Generally not as accurate
12 to 22 arc volts

20. 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
Flux cored wires
Wire feed speed
Shielding the molten weld metal from atmospheric contamination

21. What is the effect of too much slope?
Flux cored wires
Pressure - The rate of flow of a shielding gas
Insufficient current to melt the wire off cleanly
If you dont know this check your phone

22. How many times per second does short circuiting take place?
By there current carrying capacity
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

23. Why is the term GMAW preferred over MIG or MAG?
These terms are quite restrictive and often technically incorrect
Cause flaking - which can clog the liner and contact tube
SMAW - GTAW
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

24. In the GMAW process what does voltage control?
Constant voltage (CV)
SMAW - GTAW
...
Puddle fluidity

25. List the three methods of metal transfer with GMAW
Aluminum wire
Constant- speed wire feeders and Voltage- sennsing wire feeders
Short- circuiting transfer - Globular transfer - Spray transfer
AWS and CSA

26. What is an advantage of pulsed arc transfer with GMAW?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Gives arc voltage values to the control system of the feeder
If you dont know this check your phone
The time rate of response for the current rise and fall

27. Give a brief description of the GMAW process
Generally not as accurate
Welding process that joins metals by heating them with an electric arc
If you dont know this check your phone
Pressure vessels and the piping industry

28. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
Constant- speed wire feeders and Voltage- sennsing wire feeders
Reducing the gas source pressure to a constant working pressure
Pressure vessels and the piping industry

29. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
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

30. 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
Dry ice can form within the flow control openings and cause blockage of shielding gas
By there current carrying capacity

31. What is a typical flow rate of CO2 for short circuit transfer?
Motor driven generators - Transformer rectifiers - and Inverter designs
5.8 to 12.5 L/min
Higher 26 to 35 arc volts
Constant- speed wire feeders and Voltage- sennsing wire feeders

32. What does a flowmeter do and what does it measure?
Penetration and burn - off rate of the electrode
Controls the rate of flow of a shielding gas to the gun nozzle
Higher 26 to 35 arc volts
...

33. What type of power source is commonly used with a voltage sensing wire feeder?
Duty cycle
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Generally not as accurate
Constant current (CC)

34. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
85%
Voltage is the force that overcomes resistance to allow amperage flow
Wire feed speed - Voltage control

35. What effect does increasing and decreasing the inductance have on the weld?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Generally not as accurate
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
3

36. What is the required arc voltage used for short circuit transfer?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Wire feed speed
12 to 22 arc volts
To prevent leakage - Carbon Dioxide (CO2)

37. List the basic equipment requirements for the GMAW process
Dry ice can form within the flow control openings and cause blockage of shielding gas
Penetration and burn - off rate of the electrode
DCEP (Direct Current Electrode Positive) Reverse Polarity
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

38. What is the recommended electrode stick- out for .035 solid wire?
Aluminum wire
1/4 inch to 1/2 inch
Constant current (CC)
Speed of the feed motor and - starting / stopping electrode feed

39. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
To prevent drawing of liquid CO2 (Carbon Dioxide)
Duty cycle
...
3

40. What happens when the electrode extension is increased?
Shielding the molten weld metal from atmospheric contamination
These terms are quite restrictive and often technically incorrect
The Arc voltage
The resistace to electrical current flow increases with it. Causing the electrode to heat

41. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
12 to 22 arc volts
To limit the short circuiting current so that spatter is reduced
3

42. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
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
The Arc voltage
...
To limit the short circuiting current so that spatter is reduced

43. List the factors that determine the mode of metal transfer
Reducing the gas source pressure to a constant working pressure
Flux cored wires
Cause flaking - which can clog the liner and contact tube
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

44. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
Duty cycle
To prevent leakage - Carbon Dioxide (CO2)
To limit the short circuiting current so that spatter is reduced

45. List 3 forms compressed gases may be supplied for welding
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
15 feet (4.5 meters)
Reducing the gas source pressure to a constant working pressure
Penetration and burn - off rate of the electrode

46. What are the 2 types of wire feeders available?
To prevent leakage - Carbon Dioxide (CO2)
5.8 to 12.5 L/min
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Constant- speed wire feeders and Voltage- sennsing wire feeders

47. What is the preferred drive roll design for solid wires?
V groove or U groove
These terms are quite restrictive and often technically incorrect
By there current carrying capacity
To prevent leakage - Carbon Dioxide (CO2)

48. A pull type drive system is usually used on what type of material?
Minimum distortion due to low heat input
Aluminum wire
Constant- speed wire feeders and Voltage- sennsing wire feeders
Motor driven generators - Transformer rectifiers - and Inverter designs

49. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
To prevent drawing of liquid CO2 (Carbon Dioxide)
If you dont know this check your phone
Dry ice can form within the flow control openings and cause blockage of shielding gas
...

50. What does inductance control?
Minutes of elapsed time continually run (out of 10 minutes)
These terms are quite restrictive and often technically incorrect
The time rate of response for the current rise and fall
Controls the rate of flow of a shielding gas to the gun nozzle