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Test your basic knowledge |

Gas Metal Arc Welding

Instructions:

Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can study here.
Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

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 time rate of response for the current rise and fall
Wire feed speed - Voltage control
To prevent leakage - Carbon Dioxide (CO2)
SMAW - GTAW

2. List the three methods of metal transfer with GMAW
Dry ice can form within the flow control openings and cause blockage of shielding gas
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Wire feed speed
Short- circuiting transfer - Globular transfer - Spray transfer

3. Why is globular transfer generally avoided with GMAW?
Generally not as accurate
Gas metal arc welding
Spatter problems and poor weld appearance
Shielding the molten weld metal from atmospheric contamination

4. List 3 forms compressed gases may be supplied for welding
Minimum distortion due to low heat input
12 to 22 arc volts
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Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

5. When is the metal transferred with short circuit transfer?
85%
When the filler wire is in direct contract with the base metal
Motor driven generators - Transformer rectifiers - and Inverter designs
15 feet (4.5 meters)

6. What processes are constant current (CC) power sources designed to be used with?
Minutes of elapsed time continually run (out of 10 minutes)
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
V groove or U groove

7. What does the abbreviation NEMA stand for?
Controls the rate of flow of a shielding gas to the gun nozzle
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Dry ice can form within the flow control openings and cause blockage of shielding gas
National Electrical Manufactures Association

8. Give a description of 'pinch effect'
Minutes of elapsed time continually run (out of 10 minutes)
Short- circuiting transfer - Globular transfer - Spray transfer
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
To limit the short circuiting current so that spatter is reduced

9. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Wire feed speed
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Guns
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

10. Why is the term GMAW preferred over MIG or MAG?
To limit the short circuiting current so that spatter is reduced
...
These terms are quite restrictive and often technically incorrect
Gives arc voltage values to the control system of the feeder

11. What is the purpose of the shielding gas used in GMAW?
Minutes of elapsed time continually run (out of 10 minutes)
Shielding the molten weld metal from atmospheric contamination
Wire feeds smoothly (yet will slip should a problem occur in the gun)
15 feet (4.5 meters)

12. What is the key advantage of short circuiting transfer?
To prevent drawing of liquid CO2 (Carbon Dioxide)
20 to 200 times per second
Minimum distortion due to low heat input
The time rate of response for the current rise and fall

13. What is the purpose of a regulator and what does it indicate on its gauges?
Generally not as accurate
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
By there current carrying capacity
Reducing the gas source pressure to a constant working pressure

14. List several industries that would use GMAW
Pressure vessels and the piping industry
Flux cored wires
Constant- speed wire feeders and Voltage- sennsing wire feeders
Motor driven generators - Transformer rectifiers - and Inverter designs

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

16. Why is a line heater required when using GMAW?
Motor driven generators - Transformer rectifiers - and Inverter designs
Dry ice can form within the flow control openings and cause blockage of shielding gas
Reducing the gas source pressure to a constant working pressure
Cause flaking - which can clog the liner and contact tube

17. What is an advantage of pulsed arc transfer with GMAW?
Motor driven generators - Transformer rectifiers - and Inverter designs
Constant voltage (CV)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Controls the rate of flow of a shielding gas to the gun nozzle

18. In the GMAW process what does amperage control?
Penetration and burn - off rate of the electrode
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
V groove or U groove
When the filler wire is in direct contract with the base metal

19. With straight polarity where is 2/3 of the arc energy?
The Arc voltage
Welding process that joins metals by heating them with an electric arc
Voltage is the force that overcomes resistance to allow amperage flow
The negative side of a welding unit

20. Draw a typical volt amp curve for a machine that is designed for GMAW
Wire feed speed - Voltage control
5.8 to 12.5 L/min
The Arc voltage
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21. List the basic equipment requirements for the GMAW process
Higher 26 to 35 arc volts
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
To prevent leakage - Carbon Dioxide (CO2)
Pressure - The rate of flow of a shielding gas

22. What controls amperage when using GMAW?
15 feet (4.5 meters)
Flux cored wires
Wire feed speed
Short- circuiting transfer - Globular transfer - Spray transfer

23. A pull type drive system is usually used on what type of material?
15 feet (4.5 meters)
Aluminum wire
Constant- speed wire feeders and Voltage- sennsing wire feeders
12 to 22 arc volts

24. Regulators control_____________ flowmeters SHOW____________.
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
To limit the short circuiting current so that spatter is reduced
Controls the rate of flow of a shielding gas to the gun nozzle
Pressure - The rate of flow of a shielding gas

25. What does voltage do in an electrical circuit?
National Electrical Manufactures Association
Voltage is the force that overcomes resistance to allow amperage flow
Spatter problems and poor weld appearance
Minutes of elapsed time continually run (out of 10 minutes)

26. What output on the welding machine is used to rate the duty cycle?
Minutes of elapsed time continually run (out of 10 minutes)
When the filler wire is in direct contract with the base metal
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Insufficient current to melt the wire off cleanly

27. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Spatter problems and poor weld appearance
Cause flaking - which can clog the liner and contact tube
Generally not as accurate
Welding process that joins metals by heating them with an electric arc

28. What type of power source is used with a constant speed wire feeder?
Pressure - The rate of flow of a shielding gas
Constant voltage (CV)
Reducing the gas source pressure to a constant working pressure
Minimum distortion due to low heat input

29. What is the preferred drive roll design for solid wires?
National Electrical Manufactures Association
Puddle fluidity
V groove or U groove
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

30. What 2 organizations designate specifications for GMAW wires?
Constant- speed wire feeders and Voltage- sennsing wire feeders
85%
Voltage is the force that overcomes resistance to allow amperage flow
AWS and CSA

31. What is the main purpose of 'slope'?
When the filler wire is in direct contract with the base metal
Duty cycle
Wire feeds smoothly (yet will slip should a problem occur in the gun)
To limit the short circuiting current so that spatter is reduced

32. What controls the wire speed on a voltage sensing wire feeder?
Duty cycle
Higher 26 to 35 arc volts
The Arc voltage
When the filler wire is in direct contract with the base metal

33. What is the required arc voltage used for short circuit transfer?
Generally not as accurate
12 to 22 arc volts
1/4 inch to 1/2 inch
Spatter problems and poor weld appearance

34. What are the 2 types of wire feeders available?
Constant voltage (CV)
Constant- speed wire feeders and Voltage- sennsing wire feeders
AWS and CSA
The negative side of a welding unit

35. What is a typical flow rate of CO2 for short circuit transfer?
Puddle fluidity
...
5.8 to 12.5 L/min
By there current carrying capacity

36. What is the recommended electrode stick- out for .035 solid wire?
When the filler wire is in direct contract with the base metal
5.8 to 12.5 L/min
Gas metal arc welding
1/4 inch to 1/2 inch

37. What does a flowmeter do and what does it measure?
Insufficient current to melt the wire off cleanly
Controls the rate of flow of a shielding gas to the gun nozzle
AWS and CSA
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

38. What current and polarity is generally used with GMAW?
V groove or U groove
Insufficient current to melt the wire off cleanly
DCEP (Direct Current Electrode Positive) Reverse Polarity
To prevent leakage - Carbon Dioxide (CO2)

39. What type of power source is commonly used with a voltage sensing wire feeder?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Constant current (CC)
AWS and CSA
...

40. What is a solenoid valve and what actuates it?
Aluminum wire
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Spatter problems and poor weld appearance
Minutes of elapsed time continually run (out of 10 minutes)

41. A 10 minute cycle of welding time vs cooling time a given machine can handle.
AWS and CSA
Insufficient current to melt the wire off cleanly
Constant current (CC)
Duty cycle

42. Why is a fiber washer required and what cylinder gas requires it?
Duty cycle
15 feet (4.5 meters)
To prevent leakage - Carbon Dioxide (CO2)
Welding process that joins metals by heating them with an electric arc

43. What does the term GMAW identify?
Gas metal arc welding
Generally not as accurate
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Duty cycle

44. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Flux cored wires
3
Aluminum wire

45. What is the maximum distance that hard wire can be successfully pushed?
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
Motor driven generators - Transformer rectifiers - and Inverter designs
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
15 feet (4.5 meters)

46. What is another term for electrode holders for GMAW?
20 to 200 times per second
Guns
Flux cored wires
15 feet (4.5 meters)

47. List the factors that determine the mode of metal transfer
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
SMAW - GTAW
...

48. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
The time rate of response for the current rise and fall
To prevent leakage - Carbon Dioxide (CO2)
15 feet (4.5 meters)
Gives arc voltage values to the control system of the feeder

49. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
...
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Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

50. What is the effect of too much slope?
Puddle fluidity
Insufficient current to melt the wire off cleanly
3
Wire feeds smoothly (yet will slip should a problem occur in the gun)