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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 are the 2 types of wire feeders available?
These terms are quite restrictive and often technically incorrect
Constant- speed wire feeders and Voltage- sennsing wire feeders
Penetration and burn - off rate of the electrode
Wire feeds smoothly (yet will slip should a problem occur in the gun)

2. What type of power source is commonly used with a voltage sensing wire feeder?
Constant current (CC)
Puddle fluidity
85%
Pressure vessels and the piping industry

3. With straight polarity where is 2/3 of the arc energy?
Insufficient current to melt the wire off cleanly
Reducing the gas source pressure to a constant working pressure
Gas metal arc welding
The negative side of a welding unit

4. Give a description of 'pinch effect'
Guns
Duty cycle
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
The resistace to electrical current flow increases with it. Causing the electrode to heat

5. What controls amperage when using GMAW?
3
Wire feed speed
Voltage is the force that overcomes resistance to allow amperage flow
Welding process that joins metals by heating them with an electric arc

6. Why is a fiber washer required and what cylinder gas requires it?
By there current carrying capacity
AWS and CSA
Puddle fluidity
To prevent leakage - Carbon Dioxide (CO2)

7. Why is globular transfer generally avoided with GMAW?
85%
The resistace to electrical current flow increases with it. Causing the electrode to heat
Duty cycle
Spatter problems and poor weld appearance

8. Regulators control_____________ flowmeters SHOW____________.
Guns
AWS and CSA
Duty cycle
Pressure - The rate of flow of a shielding gas

9. How many times per second does short circuiting take place?
Speed of the feed motor and - starting / stopping electrode feed
20 to 200 times per second
Shielding the molten weld metal from atmospheric contamination
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

10. What happens when the electrode extension is increased?
Reducing the gas source pressure to a constant working pressure
The resistace to electrical current flow increases with it. Causing the electrode to heat
...
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

11. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Cause flaking - which can clog the liner and contact tube
Voltage is the force that overcomes resistance to allow amperage flow
When the filler wire is in direct contract with the base metal

12. What is the maximum distance that hard wire can be successfully pushed?
15 feet (4.5 meters)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Welding process that joins metals by heating them with an electric arc
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

13. In the GMAW process what does voltage control?
1/4 inch to 1/2 inch
Puddle fluidity
When the filler wire is in direct contract with the base metal
The Arc voltage

14. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
Short- circuiting transfer - Globular transfer - Spray transfer
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Gas metal arc welding

15. When is the metal transferred with short circuit transfer?
When the filler wire is in direct contract with the base metal
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Cause flaking - which can clog the liner and contact tube
Gas metal arc welding

16. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Welding process that joins metals by heating them with an electric arc
Gives arc voltage values to the control system of the feeder
(DCEP) Direct Current Electrode Positive or Reverse polarity
Short- circuiting transfer - Globular transfer - Spray transfer

17. List the basic equipment requirements for the GMAW process
The negative side of a welding unit
Pressure vessels and the piping industry
To prevent leakage - Carbon Dioxide (CO2)
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground

18. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Higher 26 to 35 arc volts
85%
20 to 200 times per second
When the filler wire is in direct contract with the base metal

19. What wire are knurled drive rolls most commonly used on?
Higher 26 to 35 arc volts
Flux cored wires
Constant voltage (CV)
The negative side of a welding unit

20. What is the effect of too much slope?
Guns
Insufficient current to melt the wire off cleanly
By there current carrying capacity
Motor driven generators - Transformer rectifiers - and Inverter designs

21. What is the main purpose of 'slope'?
15 feet (4.5 meters)
When the filler wire is in direct contract with the base metal
To limit the short circuiting current so that spatter is reduced
If you dont know this check your phone

22. Why is a line heater required when using GMAW?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Dry ice can form within the flow control openings and cause blockage of shielding gas
Spatter problems and poor weld appearance
Wire feeds smoothly (yet will slip should a problem occur in the gun)

23. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
To prevent leakage - Carbon Dioxide (CO2)
V groove or U groove
When the filler wire is in direct contract with the base metal
...

24. A pull type drive system is usually used on what type of material?
Spatter problems and poor weld appearance
Aluminum wire
3
20 to 200 times per second

25. What is the purpose of the shielding gas used in GMAW?
To prevent drawing of liquid CO2 (Carbon Dioxide)
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Pressure - The rate of flow of a shielding gas
Shielding the molten weld metal from atmospheric contamination

26. What 2 controls are found on a GMAW set- up?
5.8 to 12.5 L/min
...
AWS and CSA
Wire feed speed - Voltage control

27. What does voltage do in an electrical circuit?
To prevent leakage - Carbon Dioxide (CO2)
Wire feed speed - Voltage control
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Voltage is the force that overcomes resistance to allow amperage flow

28. What does a flowmeter do and what does it measure?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
85%
Voltage is the force that overcomes resistance to allow amperage flow
Controls the rate of flow of a shielding gas to the gun nozzle

29. What is the required arc voltage used for short circuit transfer?
The time rate of response for the current rise and fall
Wire feed speed
12 to 22 arc volts
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

30. List 3 wire drive systems and give a short description of each
Reducing the gas source pressure to a constant working pressure
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
AWS and CSA
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

31. What power sources are used with the GMAW Process?
Constant current (CC)
Motor driven generators - Transformer rectifiers - and Inverter designs
Shielding the molten weld metal from atmospheric contamination
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

32. What is the recommended electrode stick- out for .035 solid wire?
1/4 inch to 1/2 inch
(DCEP) Direct Current Electrode Positive or Reverse polarity
Dry ice can form within the flow control openings and cause blockage of shielding gas
Constant- speed wire feeders and Voltage- sennsing wire feeders

33. What is a solenoid valve and what actuates it?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Cause flaking - which can clog the liner and contact tube
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
These terms are quite restrictive and often technically incorrect

34. In the GMAW process what does amperage control?
V groove or U groove
Penetration and burn - off rate of the electrode
Dry ice can form within the flow control openings and cause blockage of shielding gas
The time rate of response for the current rise and fall

35. What 2 organizations designate specifications for GMAW wires?
AWS and CSA
DCEP (Direct Current Electrode Positive) Reverse Polarity
20 to 200 times per second
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field

36. How are GMAW guns rated?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
To prevent leakage - Carbon Dioxide (CO2)
By there current carrying capacity
The negative side of a welding unit

37. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Duty cycle
Speed of the feed motor and - starting / stopping electrode feed
Higher 26 to 35 arc volts
Constant- speed wire feeders and Voltage- sennsing wire feeders

38. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
National Electrical Manufactures Association
To prevent drawing of liquid CO2 (Carbon Dioxide)
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Gives arc voltage values to the control system of the feeder

39. What does the wire feeder control?
85%
Speed of the feed motor and - starting / stopping electrode feed
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze

40. What is a typical flow rate of CO2 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
Penetration and burn - off rate of the electrode
Constant voltage (CV)
5.8 to 12.5 L/min

41. What is the key advantage of short circuiting transfer?
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
Welding process that joins metals by heating them with an electric arc
By there current carrying capacity
Minimum distortion due to low heat input

42. A 10 minute cycle of welding time vs cooling time a given machine can handle.
DCEP (Direct Current Electrode Positive) Reverse Polarity
Minimum distortion due to low heat input
Duty cycle
Wire feed speed - Voltage control

43. What is another term for electrode holders for GMAW?
Higher 26 to 35 arc volts
Reducing the gas source pressure to a constant working pressure
Guns
By there current carrying capacity

44. Draw a typical volt amp curve for a machine that is designed for GMAW
Gives arc voltage values to the control system of the feeder
If you dont know this check your phone
Constant voltage (CV)
Motor driven generators - Transformer rectifiers - and Inverter designs

45. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
DCEP (Direct Current Electrode Positive) Reverse Polarity
When the filler wire is in direct contract with the base metal
If you dont know this check your phone
Dry ice can form within the flow control openings and cause blockage of shielding gas

46. 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
To prevent leakage - Carbon Dioxide (CO2)
The time rate of response for the current rise and fall

47. List several industries that would use GMAW
85%
Pressure - The rate of flow of a shielding gas
Spatter problems and poor weld appearance
Pressure vessels and the piping industry

48. List 3 forms compressed gases may be supplied for welding
To limit the short circuiting current so that spatter is reduced
V groove or U groove
If you dont know this check your phone
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

49. What is the disadvantage of the gauge preset type of regulator/flowmeter?
20 to 200 times per second
The Arc voltage
Cause flaking - which can clog the liner and contact tube
Generally not as accurate

50. What effect does increasing and decreasing the inductance have on the weld?
3
Penetration and burn - off rate of the electrode
Constant current (CC)
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts