Gas Metal Arc Welding

Instructions:

• Answer 50 questions in 15 minutes.
• If you are not ready to take this test, you can study here.
• 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 power sources are used with the GMAW Process?
Flux cored wires
Motor driven generators - Transformer rectifiers - and Inverter designs
3
Puddle fluidity


2. List the three methods of metal transfer with GMAW
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
(DCEP) Direct Current Electrode Positive or Reverse polarity
Short- circuiting transfer - Globular transfer - Spray transfer
DCEP (Direct Current Electrode Positive) Reverse Polarity


3. A pull type drive system is usually used on what type of material?
Insufficient current to melt the wire off cleanly
Aluminum wire
Shielding the molten weld metal from atmospheric contamination
Penetration and burn - off rate of the electrode


4. What term is used to describe when the workpiece is hooked to the negative pole on the power source?
Wire feed speed
The resistace to electrical current flow increases with it. Causing the electrode to heat
Pressure vessels and the piping industry
(DCEP) Direct Current Electrode Positive or Reverse polarity


5. What controls amperage when using GMAW?
By there current carrying capacity
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
Speed of the feed motor and - starting / stopping electrode feed
Wire feed speed


6. Give a description of 'pinch effect'
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
National Electrical Manufactures Association
Spatter problems and poor weld appearance


7. What is the minimum % value of argon that must be present to use the spray transfer method of GMAW?
Wire feed speed - Voltage control
Puddle fluidity
AWS and CSA
85%


8. What type of power source is commonly used with a voltage sensing wire feeder?
Wire feeds smoothly (yet will slip should a problem occur in the gun)
Constant current (CC)
15 feet (4.5 meters)
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze


9. Why is a fiber washer required and what cylinder gas requires it?
SMAW - GTAW
15 feet (4.5 meters)
To prevent leakage - Carbon Dioxide (CO2)
V groove or U groove


10. What output on the welding machine is used to rate the duty cycle?
Minutes of elapsed time continually run (out of 10 minutes)
1/4 inch to 1/2 inch
To prevent drawing of liquid CO2 (Carbon Dioxide)
Dry ice can form within the flow control openings and cause blockage of shielding gas


11. Is the arc voltage for spray transfer higher or lower than that used for short circuit transfer?
Higher 26 to 35 arc volts
If you dont know this check your phone
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts


12. How are GMAW guns rated?
Cause flaking - which can clog the liner and contact tube
Constant voltage (CV)
By there current carrying capacity
Puddle fluidity


13. What does voltage do in an electrical circuit?
Voltage is the force that overcomes resistance to allow amperage flow
National Electrical Manufactures Association
Speed of the feed motor and - starting / stopping electrode feed
Motor driven generators - Transformer rectifiers - and Inverter designs


14. What is the key advantage of short circuiting transfer?
Constant voltage (CV)
Generally not as accurate
Minimum distortion due to low heat input
1/4 inch to 1/2 inch


15. What does the term GMAW identify?
Shielding the molten weld metal from atmospheric contamination
Gas metal arc welding
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
Constant- speed wire feeders and Voltage- sennsing wire feeders


16. What does inductance control?
The time rate of response for the current rise and fall
Duty cycle
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


17. A machine with a 70% duty cycle can run at its max for 7 minutes with a cooling cycle of only _ minutes.
Wire feeds smoothly (yet will slip should a problem occur in the gun)
3
Constant current (CC)
15 feet (4.5 meters)


18. What is the purpose of a regulator and what does it indicate on its gauges?
The time rate of response for the current rise and fall
5.8 to 12.5 L/min
Reducing the gas source pressure to a constant working pressure
Minutes of elapsed time continually run (out of 10 minutes)


19. What controls the wire speed on a voltage sensing wire feeder?
85%
The Arc voltage
SMAW - GTAW
Controls the rate of flow of a shielding gas to the gun nozzle


20. What type of power source is used with a constant speed wire feeder?
Voltage is the force that overcomes resistance to allow amperage flow
Constant voltage (CV)
Gives arc voltage values to the control system of the feeder
National Electrical Manufactures Association


21. What is the maximum distance that hard wire can be successfully pushed?
Wire feed speed
Cause flaking - which can clog the liner and contact tube
15 feet (4.5 meters)
Wire feed speed - Voltage control


22. What is the main purpose of 'slope'?
Constant- speed wire feeders and Voltage- sennsing wire feeders
20 to 200 times per second
To limit the short circuiting current so that spatter is reduced
1/4 inch to 1/2 inch


23. What is the purpose of the pick- up lead on a voltage sensing wire feeder?
Gives arc voltage values to the control system of the feeder
Wire feed speed - Voltage control
Penetration and burn - off rate of the electrode
Gas metal arc welding


24. Why is a line heater required when using GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Flux cored wires
Insufficient current to melt the wire off cleanly
Molten metal is separated from the end of the filler wire by a squeezing force created by a magnetic field


25. Regulators control_____________ flowmeters SHOW____________.
Pressure - The rate of flow of a shielding gas
1/4 inch to 1/2 inch
Minimum distortion due to low heat input
Gas metal arc welding


26. Draw a typical volt amp curve for a machine that is designed for GMAW
SMAW - GTAW
Speed of the feed motor and - starting / stopping electrode feed
If you dont know this check your phone
Constant voltage (CV)


27. With straight polarity where is 2/3 of the arc energy?
The negative side of a welding unit
To prevent drawing of liquid CO2 (Carbon Dioxide)
Constant- speed wire feeders and Voltage- sennsing wire feeders
The time rate of response for the current rise and fall


28. What 2 controls are found on a GMAW set- up?
Wire feed speed - Voltage control
Constant voltage (CV)
Penetration and burn - off rate of the electrode
Dry ice can form within the flow control openings and cause blockage of shielding gas


29. What does the abbreviation NEMA stand for?
Flux cored wires
Gas metal arc welding
National Electrical Manufactures Association
The resistace to electrical current flow increases with it. Causing the electrode to heat


30. What current and polarity is generally used with GMAW?
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
Gives arc voltage values to the control system of the feeder
To prevent drawing of liquid CO2 (Carbon Dioxide)
DCEP (Direct Current Electrode Positive) Reverse Polarity


31. What is the preferred drive roll design for solid wires?
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
AWS and CSA
V groove or U groove
Guns


32. Draw a typical volt/amp curve that would be found with a power source designed for SMAW or GTAW
These terms are quite restrictive and often technically incorrect
Penetration and burn - off rate of the electrode
If you dont know this check your phone
Spatter problems and poor weld appearance


33. What is an advantage of pulsed arc transfer with GMAW?
Dry ice can form within the flow control openings and cause blockage of shielding gas
Minimum distortion due to low heat input
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


34. What is the reason glass 'tube' type flowmeters must have the tube mounted truly vertical?
Gas metal arc welding
20 to 200 times per second
...
Dry ice can form within the flow control openings and cause blockage of shielding gas


35. List 3 forms compressed gases may be supplied for welding
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Gives arc voltage values to the control system of the feeder
Minutes of elapsed time continually run (out of 10 minutes)
20 to 200 times per second


36. What is the recommended electrode stick- out for .035 solid wire?
Motor driven generators - Transformer rectifiers - and Inverter designs
Duty cycle
1/4 inch to 1/2 inch
Voltage is the force that overcomes resistance to allow amperage flow


37. Give a brief description of the GMAW process
Minutes of elapsed time continually run (out of 10 minutes)
Welding process that joins metals by heating them with an electric arc
Guns
The resistace to electrical current flow increases with it. Causing the electrode to heat


38. Why is globular transfer generally avoided with GMAW?
Electricaly operated valves that control the flow of shielding gas to the weld zone. The control switch located on the gun
Spatter problems and poor weld appearance
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld


39. List the basic equipment requirements for the GMAW process
1/4 inch to 1/2 inch
To prevent leakage - Carbon Dioxide (CO2)
Guns
Power source - wire feeder - welding gun - Spooled filler wire - Shielding gas - and a ground


40. How many times per second does short circuiting take place?
The time rate of response for the current rise and fall
Cause flaking - which can clog the liner and contact tube
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
20 to 200 times per second


41. What effect does increasing and decreasing the inductance have on the weld?
If you dont know this check your phone
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
Guns


42. A 10 minute cycle of welding time vs cooling time a given machine can handle.
Duty cycle
12 to 22 arc volts
Constant voltage (CV)
Motor driven generators - Transformer rectifiers - and Inverter designs


43. What is another term for electrode holders for GMAW?
National Electrical Manufactures Association
1/4 inch to 1/2 inch
5.8 to 12.5 L/min
Guns


44. Why must CO2 cylinders be used in the vertical position?
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
Aluminum wire
To prevent drawing of liquid CO2 (Carbon Dioxide)
The resistace to electrical current flow increases with it. Causing the electrode to heat


45. What processes are constant current (CC) power sources designed to be used with?
Gas metal arc welding
SMAW - GTAW
Gives arc voltage values to the control system of the feeder
Constant voltage (CV)


46. What does a flowmeter do and what does it measure?
Compressed gas cylinder - Liquid filled cylinder - or a Liquid bulk system
Controls the rate of flow of a shielding gas to the gun nozzle
DCEP (Direct Current Electrode Positive) Reverse Polarity
Heat input is less than spray transfer - resulting in less distortion - Used in all positions due to controlling the weld metal freeze


47. What is the required arc voltage used for short circuit transfer?
Minutes of elapsed time continually run (out of 10 minutes)
12 to 22 arc volts
To limit the short circuiting current so that spatter is reduced
Constant voltage (CV)


48. When is the metal transferred with short circuit transfer?
3
Gives arc voltage values to the control system of the feeder
Aluminum wire
When the filler wire is in direct contract with the base metal


49. List the factors that determine the mode of metal transfer
Controls the rate of flow of a shielding gas to the gun nozzle
Increasing inductance increases puddle fluidity - improves penatration - makes the bead flatter and smoother - and reduces spatter. To much inductance though will create erratic starts
Welding Current - Filler wire diameter - arc length - type of shielding - position of the weld
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


50. List several industries that would use GMAW
Pressure vessels and the piping industry
Insufficient current to melt the wire off cleanly
Gas metal arc welding
By there current carrying capacity