Welding Flashcards
What is your first consideration when looking at the composition of the base metal?
Which filler material to use.
Which organizations have written specifications for wire feed filler metals?
AWS and CSA
When added to filler wire, silicon, aluminum and manganese are used as what?
Deoxidizers.
What does Cast refer to?
Diameter of one wrap of the wire.
What is the purpose of wire packaged in sealed containers?
Protect it from moisture and contamination.
What is most often produced in welds made by unclean wire?
Porosity.
What are filler metals containing additional deoxidizers intended for?
Moderately rusty low-carbon steels.
What does the G stand for in the electrode classification?
General classification for electrodes not covered under any other classification.
In the GMAW short circuiting transfer mode, how is the metal transferred?
When the electrode comes in contact with the weld pool.
Very fine droplets of metal transferred across the arc in an axial fashion describes what mode of metal transfer?
Spray arc transfer.
Which mode of metal transfer is best suited for welding thin metals?
Short circuiting arc transfer.
Which MCAW mode of metal transfer is best suited for welding thin metals?
Pulsed arc transfer.
A pull type welding gun is designed to be used with what type of wire?
Soft wires.
What type of wire drive system allows greater distance from the machine to the work?
Push-pull system.
When using GMAW on mild steel, what is the most popular type of wire feed system that is used?
Push system.
Besides comfort, what is the purpose of the curved neck on a welding gun?
Ensures proper electrical transfer to the wire electrode.
What is the purpose of the welding cable assembly?
To supply current, gas and wire to the welding gun.
What are the three most used conduit liners for soft wire?
Nylon, Teflon and plastic.
What is the main purpose of the contact tube?
It transfers the welding current to the filler wire.
What is the purpose of the gas nozzle?
To transfer shielding gas onto the weld zone to prevent atmospheric contamination.
What is the longest practical feed cable used with small diameter wire and a push feed system?
15 feet.
Where are the drive rolls located on a pull type drive system?
On the gun unit.
Ideally, where should a welding power source should be located?
In an uncluttered, well ventilated area.
What position should a flow meter be mounted to obtain an accurate reading?
Vertical.
What would be the proper way to adjust the wire spool hub?
It should feed freely, yet prevent backlash when the wire feeding has stopped.
How is penetration effected when stick out is increased?
Penetration decreases.
What changes with the gun inclination?
Penetration of the weld.
What is caused by excessive splatter buildup in the gun nozzle?
Inadequate gas coverage.
What is moisture and dirt on the surface of an electrode likely to cause?
Porosity.
What is excessive drag from a dirty liner likely to cause?
Slippage or bird nesting at the drive rolls.
What is most likely causing the problem when arc hunting occurs?
Dirty contact tip or conduit liner.
What causes excessive stubbing?
Wire feed speed.
What is the major cause of cold lap when using GMAW short circuit metal transfer?
Slow travel with a large bead.
How often should you clean the conduit liner of a wire drive setup?
Every time the wire spool is changed.
What should you do when the liner becomes kinked?
Replace it.
What part of the GMAW system requires the most maintenance?
Gun and cable assembly.
What can result from a poor work lead connection?
An unstable arc.
What should be checked when adjusting from short circuiting to spray transfer with GMAW?
Make sure the gun is rated to handle higher currents.
What should be a consideration when using shielding gas in the wire feed process?
Ventilation.
High ultraviolet radiation emissions from an open arc can convert oxygen in the vicinity of the arc into what?
Ozone.
When welding, what is a potential source of poisonous chemical fumes?
Chlorinated degreasing solvents.
The process of gas metal arc welding is also known as what?
MIG welding.
What is the shielding gas generated from in self shielded FCAW?
The flux.
The MCAW process uses the same equipment as which process?
FCAW.
How are wire feed guns rated?
By current carrying capacity.
What is the major factor in choosing between an air cooled or water cooled gun?
Current and Voltage.
Welding power sources designed for wire feed welding can be used for SMAW.
False.
GMAW may be used in the semi automatic or automatic operation modes.
True.
What type of power source is most often used in GMAW?
Constant voltage.
What do constant volt machines produce?
A relatively flat volt-amp curve.
What is the best power source suited for the short circuit mode of metal transfer?
Constant voltage power source.
What type of volt-amp curve does a constant current machine produce?
Drooping.
What type of welding machine would produce an almost horizontal output slope?
Constant voltage machine.
What is one of the main advantages of metal core wire?
High deposition rates.
What does the powder in a MCAW wire mostly consist of?
Metal.
Self shielded FCAW uses what type of shielding gas?
No Gas. Flux contained within the electrode provides the shielding gas.
What is the most common duty cycle on welding machines?
60%.
Constant speed wore fee uses what type of voltage?
Constant voltage.
What type of drive roller is used wit flux core wire?
Knurled.
What is the advantage of using a 75% Argon and 25% Carbon Dioxide shielding gas?
Provides a better arc transfer.
What is the main advantage of using a metal core wire?
High deposition rates.
Spray transfer occurs when using DCEP and what minimum percent of Argon gas?
85%
What type of liner is recommended for GMAW or FCAW?
Steel.
What type of current is used in spray transfer?
Direct current electrode positive. (DCEP)
What is the most common type of gas used with constant voltage FCAW?
Carbon Dioxide and Argon.
What is the purpose of the contact tube?
To transfer voltage to the filler wire.
What is the arc length controlled by?
Voltage.
What would be an advantage to using direct current electrode negative (DCEN)?
Welding thinner gauge metals.
How are wire feed guns generally rated?
By current carrying capacity.
What are the two main types of wire feed systems?
Constant speed and voltage sensing.
Which mode of transfer used low current?
Short circuit.
What is essential to prevent shock?
Make sure all work is grounded.
Which mode of transfer is best for out of position?
Pulse.
How would you correct under cutting?
Lower travel speed.
Which polarity is used with gas metal arc welding?
Direct current electrode positive. (DCEP)
What is the primary cause of poor penetration?
Insufficient current.
The contact tip is made from what material?
Copper.
What are the flow rates for spray transfer on mild steel?
35 to 45 cfh.
Define electrode extension.
The distance between the end of the contact tube and the end of the filler wire.
What is the recommended electrode extension?
3/8” to 3/4”
What toxic gas is created when carbon dioxide is mixed with high heat?
Carbon Monoxide.
What are the main disadvantages of push feed system?
Complexity and costliness.
Which gas mix is most commonly used for spray transfer on mild steel?
85% Argon and 15% Carbon Dioxide.
At what pressure is it recommended to change out your CO² cylinder?
150 psi.
The inside diameter of your contact tip depends on what?
The diameter of your filler wire.
