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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 a typical flow rate of CO2 for short circuit transfer?
The Arc voltage
5.8 to 12.5 L/min
Shielding the molten weld metal from atmospheric contamination
15 feet (4.5 meters)

2. How are GMAW guns rated?
Higher 26 to 35 arc volts
By there current carrying capacity
DCEP (Direct Current Electrode Positive) Reverse Polarity
Minimum distortion due to low heat input

3. What 2 organizations designate specifications for GMAW wires?
Flux cored wires
Constant- speed wire feeders and Voltage- sennsing wire feeders
SMAW - GTAW
AWS and CSA

4. What is a solenoid valve and what actuates it?
Constant voltage (CV)
Constant current (CC)
Reducing the gas source pressure to a constant working pressure
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

5. List several industries that would use GMAW
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
The Arc voltage
Pressure vessels and the piping industry
Shielding the molten weld metal from atmospheric contamination

6. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Aluminum wire
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Cause flaking - which can clog the liner and contact tube
Constant voltage (CV)

7. What is the preferred drive roll design for solid wires?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
V groove or U groove
Spatter problems and poor weld appearance
Duty cycle

8. In the GMAW process what does voltage control?
5.8 to 12.5 L/min
If you dont know this check your phone
Insufficient current to melt the wire off cleanly
Puddle fluidity

9. What would be an indication that the drive roll pressure is adjusted correctly?
National Electrical Manufactures Association
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
5.8 to 12.5 L/min

10. What wire are knurled drive rolls most commonly used on?
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
85%
Flux cored wires

11. What does the term GMAW identify?
If you dont know this check your phone
Wire feed speed
Welding process that joins metals by heating them with an electric arc
Gas metal arc welding

12. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Penetration and burn - off rate of the electrode
Gives arc voltage values to the control system of the feeder
15 feet (4.5 meters)
Gas metal arc welding

13. Why must CO2 cylinders be used in the vertical position?
15 feet (4.5 meters)
Wire feed speed
Penetration and burn - off rate of the electrode
To prevent drawing of liquid CO2 (Carbon Dioxide)

14. What effect does increasing and decreasing the inductance have on the weld?
The negative side of a welding unit
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
(DCEP) Direct Current Electrode Positive or Reverse polarity
3

15. What is the main purpose of 'slope'?
Wire feed speed
By there current carrying capacity
To limit the short circuiting current so that spatter is reduced
Guns

16. List 3 forms compressed gases may be supplied for welding
When the filler wire is in direct contract with the base metal
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Gas metal arc welding
Constant voltage (CV)

17. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
To prevent leakage - Carbon Dioxide (CO2)
National Electrical Manufactures Association
Duty cycle

18. What does the wire feeder control?
Speed of the feed motor and - starting / stopping electrode feed
12 to 22 arc volts
Motor driven generators - Transformer rectifiers - and Inverter designs
Constant current (CC)

19. What does voltage do in an electrical circuit?
Reducing the gas source pressure to a constant working pressure
The negative side of a welding unit
Short- circuiting transfer - Globular transfer - Spray transfer
Voltage is the force that overcomes resistance to allow amperage flow

20. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
15 feet (4.5 meters)
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
SMAW - GTAW

21. Why is globular transfer generally avoided with GMAW?
Flux cored wires
Spatter problems and poor weld appearance
If you dont know this check your phone
When the filler wire is in direct contract with the base metal

22. What processes are constant current (CC) power sources designed to be used with?
Wire feed speed - Voltage control
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 feet (4.5 meters)
SMAW - GTAW

23. What happens when the electrode extension is increased?
The resistace to electrical current flow increases with it. Causing the electrode to heat
If you dont know this check your phone
The time rate of response for the current rise and fall
Shielding the molten weld metal from atmospheric contamination

24. What is the required arc voltage used for short circuit transfer?
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
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
12 to 22 arc volts

25. What is the purpose of the shielding gas used in GMAW?
(DCEP) Direct Current Electrode Positive or Reverse polarity
Pressure - The rate of flow of a shielding gas
20 to 200 times per second
Shielding the molten weld metal from atmospheric contamination

26. Give a description of 'pinch effect'
Spatter problems and poor weld appearance
Controls the rate of flow of a shielding gas to the gun nozzle
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Constant current (CC)

27. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Speed of the feed motor and - starting / stopping electrode feed
12 to 22 arc volts
Minutes of elapsed time continually run (out of 10 minutes)

28. What is an advantage of pulsed arc transfer with GMAW?
Insufficient current to melt the wire off cleanly
15 feet (4.5 meters)
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

29. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Gives arc voltage values to the control system of the feeder
...

30. With straight polarity where is 2/3 of the arc energy?
20 to 200 times per second
The negative side of a welding unit
The time rate of response for the current rise and fall
Cause flaking - which can clog the liner and contact tube

31. What type of power source is commonly used with a voltage sensing wire feeder?
Controls the rate of flow of a shielding gas to the gun nozzle
Flux cored wires
Constant current (CC)
Gas metal arc welding

32. What are the 2 types of wire feeders available?
Penetration and burn - off rate of the electrode
Constant- speed wire feeders and Voltage- sennsing wire feeders
Reducing the gas source pressure to a constant working pressure
These terms are quite restrictive and often technically incorrect

33. How many times per second does short circuiting take place?
Welding process that joins metals by heating them with an electric arc
20 to 200 times per second
Puddle fluidity
To prevent drawing of liquid CO2 (Carbon Dioxide)

34. What controls the wire speed on a voltage sensing wire feeder?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
The Arc voltage
If you dont know this check your phone
Cause flaking - which can clog the liner and contact tube

35. When is the metal transferred with short circuit transfer?
Minimum distortion due to low heat input
When the filler wire is in direct contract with the base metal
AWS and CSA
Pressure vessels and the piping industry

36. List 3 wire drive systems and give a short description of each
National Electrical Manufactures Association
5.8 to 12.5 L/min
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
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

37. What does inductance control?
The time rate of response for the current rise and fall
5.8 to 12.5 L/min
Pressure - The rate of flow of a shielding gas
Insufficient current to melt the wire off cleanly

38. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Motor driven generators - Transformer rectifiers - and Inverter designs
Duty cycle
The negative side of a welding unit
SMAW - GTAW

39. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
The resistace to electrical current flow increases with it. Causing the electrode to heat
85%
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Motor driven generators - Transformer rectifiers - and Inverter designs

40. In the GMAW process what does amperage control?
Gives arc voltage values to the control system of the feeder
The Arc voltage
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
Penetration and burn - off rate of the electrode

41. What type of power source is used with a constant speed wire feeder?
Constant voltage (CV)
1/4 inch to 1/2 inch
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

42. Why is a line heater required when using GMAW?
12 to 22 arc volts
Dry ice can form within the flow control openings and cause blockage of shielding gas
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Shielding the molten weld metal from atmospheric contamination

43. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
To limit the short circuiting current so that spatter is reduced
3
Voltage is the force that overcomes resistance to allow amperage flow
(DCEP) Direct Current Electrode Positive or Reverse polarity

44. List the three methods of metal transfer with GMAW
Short- circuiting transfer - Globular transfer - Spray transfer
The Arc voltage
V groove or U groove
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

45. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
...
Guns
Speed of the feed motor and - starting / stopping electrode feed
20 to 200 times per second

46. What 2 controls are found on a GMAW set- up?
Welding process that joins metals by heating them with an electric arc
Wire feed speed - Voltage control
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
Voltage is the force that overcomes resistance to allow amperage flow

47. Give a brief description of the GMAW process
When the filler wire is in direct contract with the base metal
Penetration and burn - off rate of the electrode
Welding process that joins metals by heating them with an electric arc
The time rate of response for the current rise and fall

48. What is another term for electrode holders for GMAW?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Welding process that joins metals by heating them with an electric arc
Guns
Flux cored wires

49. 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
The Arc voltage
When the filler wire is in direct contract with the base metal

50. What does the abbreviation NEMA stand for?
National Electrical Manufactures Association
To prevent drawing of liquid CO2 (Carbon Dioxide)
Constant- speed wire feeders and Voltage- sennsing wire feeders
5.8 to 12.5 L/min