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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. Give a description of 'pinch effect'
To prevent leakage - Carbon Dioxide (CO2)
DCEP (Direct Current Electrode Positive) Reverse Polarity
Minutes of elapsed time continually run (out of 10 minutes)
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

2. What is a solenoid valve and what actuates it?
Generally not as accurate
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Flux cored wires
National Electrical Manufactures Association

3. Draw a typical volt amp curve for a machine that is designed for GMAW
If you dont know this check your phone
Higher 26 to 35 arc volts
Welding process that joins metals by heating them with an electric arc
Aluminum wire

4. List several industries that would use GMAW
Pressure vessels and the piping industry
Gives arc voltage values to the control system of the feeder
Controls the rate of flow of a shielding gas to the gun nozzle
15 feet (4.5 meters)

5. List 3 wire drive systems and give a short description of each
The time rate of response for the current rise and fall
Constant- speed wire feeders and Voltage- sennsing wire feeders
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

6. 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
Generally not as accurate
Minimum distortion due to low heat input
The negative side of a welding unit

7. 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
Generally not as accurate
Pressure vessels and the piping industry
By there current carrying capacity

8. Why is the term GMAW preferred over MIG or MAG?
5.8 to 12.5 L/min
These terms are quite restrictive and often technically incorrect
Puddle fluidity
...

9. What does the wire feeder control?
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
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Wire feed speed
Speed of the feed motor and - starting / stopping electrode feed

10. With straight polarity where is 2/3 of the arc energy?
Motor driven generators - Transformer rectifiers - and Inverter designs
Minutes of elapsed time continually run (out of 10 minutes)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
The negative side of a welding unit

11. What is the preferred drive roll design for solid wires?
The time rate of response for the current rise and fall
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
If you dont know this check your phone

12. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
Pressure - The rate of flow of a shielding gas
These terms are quite restrictive and often technically incorrect
If you dont know this check your phone
Motor driven generators - Transformer rectifiers - and Inverter designs

13. In the GMAW process what does amperage control?
Puddle fluidity
If you dont know this check your phone
DCEP (Direct Current Electrode Positive) Reverse Polarity
Penetration and burn - off rate of the electrode

14. What is the maximum distance that hard wire can be successfully pushed?
15 feet (4.5 meters)
To prevent leakage - Carbon Dioxide (CO2)
SMAW - 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

15. What controls amperage when using GMAW?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Wire feed speed
If you dont know this check your phone
To prevent drawing of liquid CO2 (Carbon Dioxide)

16. What type of power source is used with a constant speed wire feeder?
3
Short- circuiting transfer - Globular transfer - Spray transfer
Constant voltage (CV)
Spatter problems and poor weld appearance

17. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
Shielding the molten weld metal from atmospheric contamination
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

18. What is the main purpose of 'slope'?
Pressure - The rate of flow of a shielding gas
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 limit the short circuiting current so that spatter is reduced
Motor driven generators - Transformer rectifiers - and Inverter designs

19. In the GMAW process what does voltage control?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Puddle fluidity
Guns
The negative side of a welding unit

20. What is the required arc voltage used for short circuit transfer?
Pressure vessels and the piping industry
Wire feeds smoothly (yet will slip should a problem occur in the gun)
When the filler wire is in direct contract with the base metal
12 to 22 arc volts

21. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Minimum distortion due to low heat input
Cause flaking - which can clog the liner and contact tube
Gives arc voltage values to the control system of the feeder
By there current carrying capacity

22. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
Gas metal arc welding
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
To prevent drawing of liquid CO2 (Carbon Dioxide)

23. What processes are constant current (CC) power sources designed to be used with?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Reducing the gas source pressure to a constant working pressure
SMAW - GTAW
Insufficient current to melt the wire off cleanly

24. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
3
(DCEP) Direct Current Electrode Positive or Reverse polarity
When the filler wire is in direct contract with the base metal

25. What happens when the electrode extension is increased?
Pressure - The rate of flow of a shielding gas
The resistace to electrical current flow increases with it. Causing the electrode to heat
Gives arc voltage values to the control system of the feeder
5.8 to 12.5 L/min

26. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
...
Pressure - The rate of flow of a shielding gas
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Penetration and burn - off rate of the electrode

27. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Penetration and burn - off rate of the electrode
1/4 inch to 1/2 inch
Higher 26 to 35 arc volts
Shielding the molten weld metal from atmospheric contamination

28. What does a flowmeter do and what does it measure?
Voltage is the force that overcomes resistance to allow amperage flow
Shielding the molten weld metal from atmospheric contamination
Controls the rate of flow of a shielding gas to the gun nozzle
Cause flaking - which can clog the liner and contact tube

29. What is the purpose of a regulator and what does it indicate on its gauges?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
National Electrical Manufactures Association
Reducing the gas source pressure to a constant working pressure
Higher 26 to 35 arc volts

30. What is a typical flow rate of CO2 for short circuit transfer?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Voltage is the force that overcomes resistance to allow amperage flow
(DCEP) Direct Current Electrode Positive or Reverse polarity
5.8 to 12.5 L/min

31. Why is a fiber washer required and what cylinder gas requires it?
These terms are quite restrictive and often technically incorrect
To prevent leakage - Carbon Dioxide (CO2)
Insufficient current to melt the wire off cleanly
Higher 26 to 35 arc volts

32. Give a brief description of the GMAW process
Welding process that joins metals by heating them with an electric arc
If you dont know this check your phone
Aluminum wire
Constant- speed wire feeders and Voltage- sennsing wire feeders

33. What 2 controls are found on a GMAW set- up?
Gives arc voltage values to the control system of the feeder
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Wire feed speed - Voltage control
Cause flaking - which can clog the liner and contact tube

34. What does the term GMAW identify?
Gas metal arc welding
To prevent leakage - Carbon Dioxide (CO2)
Wire feed speed - Voltage control
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

35. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Wire feeds smoothly (yet will slip should a problem occur in the gun)
V groove or U groove
15 feet (4.5 meters)

36. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
12 to 22 arc volts
Cause flaking - which can clog the liner and contact tube
85%
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

37. A 10 minute cycle of welding time vs cooling time a given machine can handle.
National Electrical Manufactures Association
Spatter problems and poor weld appearance
Penetration and burn - off rate of the electrode
Duty cycle

38. Why must CO2 cylinders be used in the vertical position?
To prevent drawing of liquid CO2 (Carbon Dioxide)
DCEP (Direct Current Electrode Positive) Reverse Polarity
3
If you dont know this check your phone

39. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Wire feed speed - Voltage control
To prevent drawing of liquid CO2 (Carbon Dioxide)
Dry ice can form within the flow control openings and cause blockage of shielding gas
Cause flaking - which can clog the liner and contact tube

40. What output on the welding machine is used to rate the duty cycle?
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)
20 to 200 times per second
85%

41. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
AWS and CSA
Higher 26 to 35 arc volts
Pressure vessels and the piping industry

42. When is the metal transferred with short circuit transfer?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
The resistace to electrical current flow increases with it. Causing the electrode to heat
When the filler wire is in direct contract with the base metal

43. What does inductance control?
20 to 200 times per second
Guns
Aluminum wire
The time rate of response for the current rise and fall

44. What 2 organizations designate specifications for GMAW wires?
AWS and CSA
Dry ice can form within the flow control openings and cause blockage of shielding gas
If you dont know this check your phone
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

45. What controls the wire speed on a voltage sensing wire feeder?
The Arc voltage
Welding process that joins metals by heating them with an electric arc
Constant voltage (CV)
Motor driven generators - Transformer rectifiers - and Inverter designs

46. How many times per second does short circuiting take place?
...
20 to 200 times per second
Pressure - The rate of flow of a shielding gas
Speed of the feed motor and - starting / stopping electrode feed

47. What power sources are used with the GMAW Process?
Duty cycle
Voltage is the force that overcomes resistance to allow amperage flow
These terms are quite restrictive and often technically incorrect
Motor driven generators - Transformer rectifiers - and Inverter designs

48. A pull type drive system is usually used on what type of material?
Gives arc voltage values to the control system of the feeder
These terms are quite restrictive and often technically incorrect
Aluminum wire
The Arc voltage

49. What is an advantage of pulsed arc transfer with GMAW?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Motor driven generators - Transformer rectifiers - and Inverter designs
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

50. Why is a line heater required when using GMAW?
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
To prevent drawing of liquid CO2 (Carbon Dioxide)
The time rate of response for the current rise and fall