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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. Why must CO2 cylinders be used in the vertical position?
3
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
To limit the short circuiting current so that spatter is reduced
To prevent drawing of liquid CO2 (Carbon Dioxide)

2. What does the wire feeder control?
Puddle fluidity
Speed of the feed motor and - starting / stopping electrode feed
Reducing the gas source pressure to a constant working pressure
SMAW - GTAW

3. Draw a typical volt amp curve for a machine that is designed for GMAW
If you dont know this check your phone
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Guns
(DCEP) Direct Current Electrode Positive or Reverse polarity

4. Regulators control_____________ flowmeters SHOW____________.
These terms are quite restrictive and often technically incorrect
Pressure - The rate of flow of a shielding gas
Cause flaking - which can clog the liner and contact tube
Reducing the gas source pressure to a constant working pressure

5. A pull type drive system is usually used on what type of material?
Aluminum wire
Voltage is the force that overcomes resistance to allow amperage flow
Duty cycle
DCEP (Direct Current Electrode Positive) Reverse Polarity

6. What output on the welding machine is used to rate the duty cycle?
Pressure - The rate of flow of a shielding gas
To prevent leakage - Carbon Dioxide (CO2)
Minutes of elapsed time continually run (out of 10 minutes)
Penetration and burn - off rate of the electrode

7. What 2 organizations designate specifications for GMAW wires?
(DCEP) Direct Current Electrode Positive or Reverse polarity
The negative side of a welding unit
Welding process that joins metals by heating them with an electric arc
AWS and CSA

8. What is the purpose of a regulator and what does it indicate on its gauges?
Duty cycle
...
Gives arc voltage values to the control system of the feeder
Reducing the gas source pressure to a constant working pressure

9. What is the effect of too much slope?
Insufficient current to melt the wire off cleanly
Cause flaking - which can clog the liner and contact tube
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Wire feed speed

10. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
By there current carrying capacity
...
(DCEP) Direct Current Electrode Positive or Reverse polarity
When the filler wire is in direct contract with the base metal

11. Why is the term GMAW preferred over MIG or MAG?
Shielding the molten weld metal from atmospheric contamination
These terms are quite restrictive and often technically incorrect
The resistace to electrical current flow increases with it. Causing the electrode to heat
Short- circuiting transfer - Globular transfer - Spray transfer

12. Why is globular transfer generally avoided with GMAW?
The time rate of response for the current rise and fall
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
Spatter problems and poor weld appearance
Minimum distortion due to low heat input

13. What type of power source is used with a constant speed wire feeder?
Constant- speed wire feeders and Voltage- sennsing wire feeders
Constant voltage (CV)
Guns
To prevent leakage - Carbon Dioxide (CO2)

14. When is the metal transferred with short circuit transfer?
DCEP (Direct Current Electrode Positive) Reverse Polarity
When the filler wire is in direct contract with the base metal
Wire feed speed - Voltage control
Higher 26 to 35 arc volts

15. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
These terms are quite restrictive and often technically incorrect
Higher 26 to 35 arc volts
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts

16. What is the main purpose of 'slope'?
To limit the short circuiting current so that spatter is reduced
1/4 inch to 1/2 inch
20 to 200 times per second
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

17. What does a flowmeter do and what does it measure?
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
Wire feeds smoothly (yet will slip should a problem occur in the gun)

18. Give a brief description of the GMAW process
By there current carrying capacity
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
Gas metal arc welding

19. In the GMAW process what does voltage control?
The Arc voltage
To prevent drawing of liquid CO2 (Carbon Dioxide)
Puddle fluidity
Constant- speed wire feeders and Voltage- sennsing wire feeders

20. List the basic equipment requirements for the GMAW process
The resistace to electrical current flow increases with it. Causing the electrode to heat
Flux cored wires
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

21. What is an advantage of pulsed arc transfer with GMAW?
If you dont know this check your phone
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze
1/4 inch to 1/2 inch
The negative side of a welding unit

22. List 3 wire drive systems and give a short description of each
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
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
5.8 to 12.5 L/min

23. Why is a fiber washer required and what cylinder gas requires it?
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Minimum distortion due to low heat input
Gas metal arc welding
To prevent leakage - Carbon Dioxide (CO2)

24. What is a typical flow rate of CO2 for short circuit transfer?
85%
Controls the rate of flow of a shielding gas to the gun nozzle
Pressure - The rate of flow of a shielding gas
5.8 to 12.5 L/min

25. What does voltage do in an electrical circuit?
If you dont know this check your phone
Controls the rate of flow of a shielding gas to the gun nozzle
National Electrical Manufactures Association
Voltage is the force that overcomes resistance to allow amperage flow

26. What is the maximum distance that hard wire can be successfully pushed?
Constant voltage (CV)
Motor driven generators - Transformer rectifiers - and Inverter designs
15 feet (4.5 meters)
85%

27. What are the 2 types of wire feeders available?
Shielding the molten weld metal from atmospheric contamination
Constant- speed wire feeders and Voltage- sennsing wire feeders
Pressure - The rate of flow of a shielding gas
Short- circuiting transfer - Globular transfer - Spray transfer

28. What is the key advantage of short circuiting transfer?
The Arc voltage
12 to 22 arc volts
1/4 inch to 1/2 inch
Minimum distortion due to low heat input

29. What is another term for electrode holders for GMAW?
Wire feed speed - Voltage control
DCEP (Direct Current Electrode Positive) Reverse Polarity
Guns
To limit the short circuiting current so that spatter is reduced

30. What effect does increasing and decreasing the inductance have on the weld?
By there current carrying capacity
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
The negative side of a welding unit

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
To prevent leakage - Carbon Dioxide (CO2)
V groove or U groove
Speed of the feed motor and - starting / stopping electrode feed

32. What is the disadvantage of the gauge preset type of regulator/flowmeter?
Generally not as accurate
Motor driven generators - Transformer rectifiers - and Inverter designs
Minimum distortion due to low heat input
Pressure - The rate of flow of a shielding gas

33. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Pressure - The rate of flow of a shielding gas
85%
V groove or U groove

34. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
1/4 inch to 1/2 inch
If you dont know this check your phone
The Arc voltage
3

35. Give a description of 'pinch effect'
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
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
V groove or U groove

36. What controls the wire speed on a voltage sensing wire feeder?
3
Constant voltage (CV)
Pressure - The rate of flow of a shielding gas
The Arc voltage

37. List 3 forms compressed gases may be supplied for welding
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Gas metal arc welding
Constant- speed wire feeders and Voltage- sennsing wire feeders
Gives arc voltage values to the control system of the feeder

38. What power sources are used with the GMAW Process?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Pressure vessels and the piping industry
Duty cycle
Motor driven generators - Transformer rectifiers - and Inverter designs

39. What is the recommended electrode stick- out for .035 solid wire?
Minimum distortion due to low heat input
V groove or U groove
1/4 inch to 1/2 inch
The Arc voltage

40. What type of power source is commonly used with a voltage sensing wire feeder?
These terms are quite restrictive and often technically incorrect
If you dont know this check your phone
Constant current (CC)
3

41. What is the purpose of the shielding gas used in GMAW?
Shielding the molten weld metal from atmospheric contamination
5.8 to 12.5 L/min
Duty cycle
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

42. List the three methods of metal transfer with GMAW
Cause flaking - which can clog the liner and contact tube
Puddle fluidity
Short- circuiting transfer - Globular transfer - Spray transfer
Wire feed speed - Voltage control

43. When using flat drive rolls with too much pressure on copper coated solid wires what problem could take place?
Cause flaking - which can clog the liner and contact tube
Welding process that joins metals by heating them with an electric arc
1/4 inch to 1/2 inch
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun

44. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
Generally not as accurate
Pressure - The rate of flow of a shielding gas
Welding process that joins metals by heating them with an electric arc

45. What processes are constant current (CC) power sources designed to be used with?
SMAW - GTAW
15 feet (4.5 meters)
(DCEP) Direct Current Electrode Positive or Reverse polarity
Speed of the feed motor and - starting / stopping electrode feed

46. What does the term GMAW identify?
When the filler wire is in direct contract with the base metal
Gas metal arc welding
12 to 22 arc volts
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system

47. What current and polarity is generally used with GMAW?
DCEP (Direct Current Electrode Positive) Reverse Polarity
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
85%
To prevent leakage - Carbon Dioxide (CO2)

48. What 2 controls are found on a GMAW set- up?
Motor driven generators - Transformer rectifiers - and Inverter designs
Pressure vessels and the piping industry
Wire feed speed - Voltage control
Dry ice can form within the flow control openings and cause blockage of shielding gas

49. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
Short- circuiting transfer - Globular transfer - Spray transfer
(DCEP) Direct Current Electrode Positive or Reverse polarity
Flux cored wires

50. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Cause flaking - which can clog the liner and contact tube
(DCEP) Direct Current Electrode Positive or Reverse polarity
20 to 200 times per second
To prevent leakage - Carbon Dioxide (CO2)