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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 is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Aluminum wire
85%
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Pressure vessels and the piping industry

2. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
Higher 26 to 35 arc volts
The negative side of a welding unit
By there current carrying capacity

3. Why is a line heater required when using GMAW?
Penetration and burn - off rate of the electrode
Gas metal arc welding
If you dont know this check your phone
Dry ice can form within the flow control openings and cause blockage of shielding gas

4. In the GMAW process what does voltage control?
Insufficient current to melt the wire off cleanly
Short- circuiting transfer - Globular transfer - Spray transfer
Puddle fluidity
SMAW - GTAW

5. What is a typical flow rate of CO2 for short circuit transfer?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Penetration and burn - off rate of the electrode
AWS and CSA
5.8 to 12.5 L/min

6. What processes are constant current (CC) power sources designed to be used with?
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 drawing of liquid CO2 (Carbon Dioxide)
SMAW - GTAW
Welding process that joins metals by heating them with an electric arc

7. What is the key advantage of short circuiting transfer?
Minimum distortion due to low heat input
Shielding the molten weld metal from atmospheric contamination
Welding process that joins metals by heating them with an electric arc
1/4 inch to 1/2 inch

8. Why must CO2 cylinders be used in the vertical position?
15 feet (4.5 meters)
Penetration and burn - off rate of the electrode
Cause flaking - which can clog the liner and contact tube
To prevent drawing of liquid CO2 (Carbon Dioxide)

9. What power sources are used with the GMAW Process?
Motor driven generators - Transformer rectifiers - and Inverter designs
Generally not as accurate
Duty cycle
SMAW - GTAW

10. What does a flowmeter do and what does it measure?
Controls the rate of flow of a shielding gas to the gun nozzle
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
1/4 inch to 1/2 inch
Shielding the molten weld metal from atmospheric contamination

11. What does the wire feeder control?
Spatter problems and poor weld appearance
Speed of the feed motor and - starting / stopping electrode feed
Gas metal arc welding
Constant- speed wire feeders and Voltage- sennsing wire feeders

12. List 3 wire drive systems and give a short description of each
Controls the rate of flow of a shielding gas to the gun nozzle
20 to 200 times per second
Insufficient current to melt the wire off cleanly
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

13. List the basic equipment requirements for the GMAW process
85%
Gas metal arc welding
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
If you dont know this check your phone

14. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
3
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
Penetration and burn - off rate of the electrode

15. List 3 forms compressed gases may be supplied for welding
To prevent drawing of liquid CO2 (Carbon Dioxide)
Higher 26 to 35 arc volts
Short- circuiting transfer - Globular transfer - Spray transfer
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

16. In the GMAW process what does amperage control?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Penetration and burn - off rate of the electrode
Aluminum wire

17. What does the term GMAW identify?
Gas metal arc welding
When the filler wire is in direct contract with the base metal
85%
Wire feed speed

18. List the factors that determine the mode of metal transfer
To prevent leakage - Carbon Dioxide (CO2)
Minimum distortion due to low heat input
AWS and CSA
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld

19. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Wire feed speed
...
Minimum distortion due to low heat input
Guns

20. What is the main purpose of 'slope'?
Higher 26 to 35 arc volts
Voltage is the force that overcomes resistance to allow amperage flow
To limit the short circuiting current so that spatter is reduced
The negative side of a welding unit

21. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Reducing the gas source pressure to a constant working pressure
Gives arc voltage values to the control system of the feeder
AWS and CSA
V groove or U groove

22. What output on the welding machine is used to rate the duty cycle?
3
...
The negative side of a welding unit
Minutes of elapsed time continually run (out of 10 minutes)

23. What 2 controls are found on a GMAW set- up?
Pressure vessels and the piping industry
If you dont know this check your phone
Wire feed speed - Voltage control
The negative side of a welding unit

24. Draw a typical volt amp curve for a machine that is designed for GMAW
Controls the rate of flow of a shielding gas to the gun nozzle
Constant- speed wire feeders and Voltage- sennsing wire feeders
If you dont know this check your phone
Duty cycle

25. When is the metal transferred with short circuit transfer?
When the filler wire is in direct contract with the base metal
SMAW - GTAW
3
The negative side of a welding unit

26. What is another term for electrode holders for GMAW?
12 to 22 arc volts
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
The negative side of a welding unit
Guns

27. What is a solenoid valve and what actuates it?
Constant current (CC)
3
By there current carrying capacity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

28. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
(DCEP) Direct Current Electrode Positive or Reverse polarity
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Cause flaking - which can clog the liner and contact tube

29. Give a description of 'pinch effect'
Motor driven generators - Transformer rectifiers - and Inverter designs
Spatter problems and poor weld appearance
3
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

30. Give a brief description of the GMAW process
National Electrical Manufactures Association
Guns
Welding process that joins metals by heating them with an electric arc
Puddle fluidity

31. 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
Wire feed speed
Controls the rate of flow of a shielding gas to the gun nozzle
V groove or U groove

32. A pull type drive system is usually used on what type of material?
Flux cored wires
Aluminum wire
Welding process that joins metals by heating them with an electric arc
Higher 26 to 35 arc volts

33. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
The Arc voltage
Cause flaking - which can clog the liner and contact tube
Welding process that joins metals by heating them with an electric arc
Gives arc voltage values to the control system of the feeder

34. What is the effect of too much slope?
If you dont know this check your phone
Insufficient current to melt the wire off cleanly
Voltage is the force that overcomes resistance to allow amperage flow
Minimum distortion due to low heat input

35. What are the 2 types of wire feeders available?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Voltage is the force that overcomes resistance to allow amperage flow
Motor driven generators - Transformer rectifiers - and Inverter designs
V groove or U groove

36. List several industries that would use GMAW
Cause flaking - which can clog the liner and contact tube
3
Flux cored wires
Pressure vessels and the piping industry

37. What is the maximum distance that hard wire can be successfully pushed?
If you dont know this check your phone
15 feet (4.5 meters)
Guns
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

38. Regulators control_____________ flowmeters SHOW____________.
To prevent drawing of liquid CO2 (Carbon Dioxide)
The time rate of response for the current rise and fall
Dry ice can form within the flow control openings and cause blockage of shielding gas
Pressure - The rate of flow of a shielding gas

39. Why is the term GMAW preferred over MIG or MAG?
Short- circuiting transfer - Globular transfer - Spray transfer
These terms are quite restrictive and often technically incorrect
85%
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

40. How many times per second does short circuiting take place?
20 to 200 times per second
The Arc voltage
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

41. Why is globular transfer generally avoided with GMAW?
Wire feed speed - Voltage control
Gas metal arc welding
Shielding the molten weld metal from atmospheric contamination
Spatter problems and poor weld appearance

42. What is the recommended electrode stick- out for .035 solid wire?
Welding process that joins metals by heating them with an electric arc
Motor driven generators - Transformer rectifiers - and Inverter designs
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
1/4 inch to 1/2 inch

43. What is the disadvantage of the gauge preset type of regulator/flowmeter?
By there current carrying capacity
Controls the rate of flow of a shielding gas to the gun nozzle
Generally not as accurate
Dry ice can form within the flow control openings and cause blockage of shielding gas

44. What is the purpose of the shielding gas used in GMAW?
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Welding process that joins metals by heating them with an electric arc
Shielding the molten weld metal from atmospheric contamination
The resistace to electrical current flow increases with it. Causing the electrode to heat

45. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
Pressure vessels and the piping industry
Shielding the molten weld metal from atmospheric contamination
Voltage is the force that overcomes resistance to allow amperage flow

46. What does the abbreviation NEMA stand for?
15 feet (4.5 meters)
Reducing the gas source pressure to a constant working pressure
National Electrical Manufactures Association
Higher 26 to 35 arc volts

47. What controls amperage when using GMAW?
National Electrical Manufactures Association
Cause flaking - which can clog the liner and contact tube
Reducing the gas source pressure to a constant working pressure
Wire feed speed

48. What does voltage do in an electrical circuit?
Minutes of elapsed time continually run (out of 10 minutes)
Voltage is the force that overcomes resistance to allow amperage flow
Motor driven generators - Transformer rectifiers - and Inverter designs
The Arc voltage

49. What effect does increasing and decreasing the inductance have on the weld?
Higher 26 to 35 arc volts
Motor driven generators - Transformer rectifiers - and Inverter designs
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

50. What is the required arc voltage used for short circuit transfer?
12 to 22 arc volts
...
Minimum distortion due to low heat input
Dry ice can form within the flow control openings and cause blockage of shielding gas