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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.
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 current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
5.8 to 12.5 L/min
When the filler wire is in direct contract with the base metal
Controls the rate of flow of a shielding gas to the gun nozzle

2. What is the purpose of the shielding gas used in GMAW?
Gas metal arc welding
Dry ice can form within the flow control openings and cause blockage of shielding gas
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Shielding the molten weld metal from atmospheric contamination

3. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
If you dont know this check your phone
By there current carrying capacity
The time rate of response for the current rise and fall

4. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Penetration and burn - off rate of the electrode
These terms are quite restrictive and often technically incorrect
(DCEP) Direct Current Electrode Positive or Reverse polarity
Duty cycle

5. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
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
National Electrical Manufactures Association
3

6. What is another term for electrode holders for GMAW?
Spatter problems and poor weld appearance
Guns
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Cause flaking - which can clog the liner and contact tube

7. What would be an indication that the drive roll pressure is adjusted correctly?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Wire feeds smoothly (yet will slip should a problem occur in the gun)
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
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

8. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
The resistace to electrical current flow increases with it. Causing the electrode to heat
DCEP (Direct Current Electrode Positive) Reverse Polarity
To limit the short circuiting current so that spatter is reduced

9. What is the required arc voltage used for short circuit transfer?
85%
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
12 to 22 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

10. When is the metal transferred with short circuit transfer?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Aluminum wire
Puddle fluidity
When the filler wire is in direct contract with the base metal

11. What does a flowmeter do and what does it measure?
Minimum distortion due to low heat input
Controls the rate of flow of a shielding gas to the gun nozzle
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Insufficient current to melt the wire off cleanly

12. What type of power source is commonly used with a voltage sensing wire feeder?
Guns
Constant current (CC)
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

13. Give a description of 'pinch effect'
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
These terms are quite restrictive and often technically incorrect
Controls the rate of flow of a shielding gas to the gun nozzle
20 to 200 times per second

14. What output on the welding machine is used to rate the duty cycle?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Minutes of elapsed time continually run (out of 10 minutes)
Insufficient current to melt the wire off cleanly
Voltage is the force that overcomes resistance to allow amperage flow

15. What is the disadvantage of the gauge preset type of regulator/flowmeter?
85%
Generally not as accurate
Shielding the molten weld metal from atmospheric contamination
Dry ice can form within the flow control openings and cause blockage of shielding gas

16. What is the preferred drive roll design for solid wires?
Constant current (CC)
V groove or U groove
Generally not as accurate
The time rate of response for the current rise and fall

17. A pull type drive system is usually used on what type of material?
Constant current (CC)
Aluminum wire
12 to 22 arc volts
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

18. List 3 forms compressed gases may be supplied for welding
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Duty cycle
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

19. Why must CO2 cylinders be used in the vertical position?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Aluminum wire
Voltage is the force that overcomes resistance to allow amperage flow
To prevent drawing of liquid CO2 (Carbon Dioxide)

20. What effect does increasing and decreasing the inductance have on the weld?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
20 to 200 times per second

21. Why is a line heater required when using GMAW?
Minutes of elapsed time continually run (out of 10 minutes)
Dry ice can form within the flow control openings and cause blockage of shielding gas
Short- circuiting transfer - Globular transfer - Spray transfer
The negative side of a welding unit

22. What is the maximum distance that hard wire can be successfully pushed?
The Arc voltage
Speed of the feed motor and - starting / stopping electrode feed
15 feet (4.5 meters)
1/4 inch to 1/2 inch

23. In the GMAW process what does voltage control?
AWS and CSA
DCEP (Direct Current Electrode Positive) Reverse Polarity
Puddle fluidity
Duty cycle

24. Regulators control_____________ flowmeters SHOW____________.
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
Pressure - The rate of flow of a shielding gas
Gives arc voltage values to the control system of the feeder
Aluminum wire

25. What is the key advantage of short circuiting transfer?
Wire feed speed
Minimum distortion due to low heat input
Motor driven generators - Transformer rectifiers - and Inverter designs
If you dont know this check your phone

26. How many times per second does short circuiting take place?
Gas metal arc welding
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
The Arc voltage
20 to 200 times per second

27. What happens when the electrode extension is increased?
Insufficient current to melt the wire off cleanly
The resistace to electrical current flow increases with it. Causing the electrode to heat
Dry ice can form within the flow control openings and cause blockage of shielding gas
Higher 26 to 35 arc volts

28. What does inductance control?
The time rate of response for the current rise and fall
If you dont know this check your phone
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
Puddle fluidity

29. What does the wire feeder control?
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
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

30. What 2 organizations designate specifications for GMAW wires?
AWS and CSA
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Welding process that joins metals by heating them with an electric arc
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

31. What controls the wire speed on a voltage sensing wire feeder?
The negative side of a welding unit
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
Motor driven generators - Transformer rectifiers - and Inverter designs

32. What does the term GMAW identify?
15 feet (4.5 meters)
These terms are quite restrictive and often technically incorrect
National Electrical Manufactures Association
Gas metal arc welding

33. How are GMAW guns rated?
By there current carrying capacity
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Penetration and burn - off rate of the electrode
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

34. List 3 wire drive systems and give a short description of each
To prevent leakage - Carbon Dioxide (CO2)
Gives arc voltage values to the control system of the feeder
Pressure vessels and the piping industry
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

35. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Gives arc voltage values to the control system of the feeder
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
Constant current (CC)

36. What controls amperage when using GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Wire feed speed
Duty cycle
To limit the short circuiting current so that spatter is reduced

37. What is a solenoid valve and what actuates it?
Minutes of elapsed time continually run (out of 10 minutes)
V groove or U groove
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Flux cored wires

38. What power sources are used with the GMAW Process?
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
To prevent leakage - Carbon Dioxide (CO2)
Motor driven generators - Transformer rectifiers - and Inverter designs
Gives arc voltage values to the control system of the feeder

39. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Speed of the feed motor and - starting / stopping electrode feed
To prevent drawing of liquid CO2 (Carbon Dioxide)
85%
20 to 200 times per second

40. What is a typical flow rate of CO2 for short circuit transfer?
Generally not as accurate
Voltage is the force that overcomes resistance to allow amperage flow
5.8 to 12.5 L/min
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

41. What wire are knurled drive rolls most commonly used on?
Flux cored wires
To prevent drawing of liquid CO2 (Carbon Dioxide)
Guns
3

42. What does voltage do in an electrical circuit?
Constant current (CC)
If you dont know this check your phone
Penetration and burn - off rate of the electrode
Voltage is the force that overcomes resistance to allow amperage flow

43. Why is a fiber washer required and what cylinder gas requires it?
To prevent leakage - Carbon Dioxide (CO2)
Minutes of elapsed time continually run (out of 10 minutes)
To prevent drawing of liquid CO2 (Carbon Dioxide)
Constant- speed wire feeders and Voltage- sennsing wire feeders

44. Give a brief description of the GMAW process
Pressure vessels and the piping industry
SMAW - GTAW
Minutes of elapsed time continually run (out of 10 minutes)
Welding process that joins metals by heating them with an electric arc

45. What is the main purpose of 'slope'?
20 to 200 times per second
85%
Controls the rate of flow of a shielding gas to the gun nozzle
To limit the short circuiting current so that spatter is reduced

46. 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
Puddle fluidity
Spatter problems and poor weld appearance
(DCEP) Direct Current Electrode Positive or Reverse polarity

47. 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
The negative side of a welding unit
15 feet (4.5 meters)
Wire feeds smoothly (yet will slip should a problem occur in the gun)

48. What are the 2 types of wire feeders available?
Puddle fluidity
Constant- speed wire feeders and Voltage- sennsing wire feeders
Guns
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

49. Why is globular transfer generally avoided with GMAW?
Spatter problems and poor weld appearance
1/4 inch to 1/2 inch
...
Minutes of elapsed time continually run (out of 10 minutes)

50. 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
Guns
...