WD 110 Final
Which of the following gases is the least dense
Helium
Welds that are more difficult to perform than most other welds
Horizontal butt
Provide the necessary shielding because they do not form compounds with any other substance
Inert gases
In a (n) ____________ welding machine the incoming power is changed from 60 cycles per second to several thousand cycles per second
Inverter
A (n) _______ Joint is made by overlapping the edges of two plates, and can be welded on one side or both sides with a fillet weld
Lap
A (n) _________ Electrode angle pushes the molten metal and slag ahead of the weld
Leading
What can a welder do to prevent possibly swaying while welding
Lean against or hold onto a stable object
What can be done to keep the spatter to a minimum when using CO2 as a shielding gas?
Maintain a very short uniform arc length while welding
What can a welder do to make the necessary adjustments in the set up and manipulation to achieve a good weld
Make a few test welds
Is a thin layer of dark gray or black iron oxide formed during the rolling process
Mill scale
___ Machines are adjusted by turning a handwheel that moves the internal parts closer together or farther apart
Moveable coil
What material should shielding gas hoses be made of
Plastic
At low amperages and high voltage settings the wire may
Pop violently as a result of the uncontrolled arc
How should the conduit or an extension be aligned with the grooved rollers
Set as close as possible without touching the roller
The only difference between all GMA welding machines and some FCA welding machines is that all GMA welding machines must have a
Shielding gas solenoid
Is true of breaking and remelting tungsten
Should be broken squarely
A work clamp_
Should be carefully touched occasionally to determine if it is hot
Which of the following is true of erosion of the tungsten electrode
Slow erosion results in limited tungsten inclusions in the weld
Welding with the current set to high results in...
Spatter
A transformer with more turns of wire in the primary winding then in the secondary winding is known as a
Step down transformer
If arc length is shortened metal transferring across the gap may short out the electrode causing it to
Stick to the plate
Well that is high and has little or no fusion is too cold. to correct this...
Stop welding and make the needed adjustments
A (n) _______ joint is made by tack welding one piece of metal on another piece of metal at a right angle
T
The quantity of heat in a material is a function of both
Temperature, mass
Why is an inert shielding gas required for GTA welding?
To keep the air away from the hot tungsten and molten weld metal
Why is it important to keep portable welders properly tuned?
To reduce air pollution.
When the shielding gas flow rate is high, air is drawn into the gas envelope by a(n) _________ effect around the edge of the nozzle
Venturi
_________ Measure of electric pressure
Voltage
The unit of measure of electrical pressure is
Volts
Measurement of amount of electrical energy or power in the arc
Wattage
Measurement of the amount of electrical energy or power in the arc
Wattage
Slight changes in ____ Can be used to control the world as the groove spacing changes
Welding gun angle
When used as pure gases for welding ferrous metals, ____ may produce an erratic arc action, promote undercutting, and result in other flaws.
argon and helium
In generators the welding current is produced on the ____.
armature
Welding cables should _______.
be sufficiently long to reach the work station
The correct flow of a shielding gas can be set by ____
checking welding guides
The longer the ____, the greater the ____ to the welding current.
electrode extension, resistance
The _____ at which an alternating current cycles is the rate at which it makes a full change in direction
frequency
Resistance to the flow of electrons produces
heat
A weld bead made at a(n) ____________________ amperage setting is wide and flat with deep penetration, produces excessive spatter, and is mostly hard.
high
Water hose fittings have ____ threads, and gas hose fittings have ____ threads.
left hand, right hand
At any one voltage setting, ____ amperage is required to melt the wire the ____ it is fed.
more, faster
The ____ machine allows the selection of different current settings by tapping into the secondary coil at a different turn value.
multiple-coil
A ____ gap may require ____.
narrow, more penetration
In GMA welding, the voltage is set ____ and the amperage is set ____.
on the welder, by changing the wire-feed speed
The space between plates in a square butt joint is called
root gap
A 60% duty cycle means that the machine can be used a total of _____ minutes out of every ten minutes at the maximum rated current.
six
To make threading electrode wire easier, ____.
straighten about 12 in. of the end of the wire and cut off any kinks
Mixtures of argon with less than ____ percent carbon dioxide may not have enough arc voltage to give desired results.
ten
A _____ electrode angle pushes the molten metal away from the leading edge of the molten weld pool toward the back where it solidifies
trailing
Controls the maximum gap the electrons can jump to form the arc
voltage
The temperature of a welding arc is dependent on the ____, arc length, and atmosphere
voltage
The terms welding cables and ____ mean the same thing.
welding leads
SMAW is a widely used welding process because
Low cost, flexibility, portability and versatility. (All of the above)
A (n) _______ Joint is made by placing plates at a 90° angle to each other with the edges forming a V groove
Outside corner
To correct_____ Problem a welder can use a smaller electrode at a lower current setting
Overheating
Protects the molten weld pool, the filler rod, and the tungsten electrode as they cool to a temperature at which they will not oxidize rapidly
Postflow period
Tungsten electrodes that contain elements such as lanthanum or yttrium are referred to as...
Rare earth tungstens
What is the purpose of a gas lens
Reduces the turbulence in the shielding gas
Work angle
Relationship between center of electrode and surface of the work
Important to make cuts in the clean metal between welds on practice, why?
Reuse practice plates
Open circuit voltage
The voltage at the electrode before striking an arc.
In a standard welding transformer, the size of the iron core is determined by ______.
the length of time it takes for the magnetic field to build up and collapse
The selection of the correct size of welding electrode is determined by
the thickness and size of the metal
Large diameter electrodes may overheat the metal if..
they are used with thin or small pieces of metal
High gas flow rates ____.
waste shielding gases
DCEP concentrates ______ of the arc heat on the plate, and _____ of the heat on the electrode.
1/3, 2/3
If the current is set too high, the electrode covering is discolored more than ____ from the end of the electrode.
1/8 in. to 1/4 in.
DECN concentrates about ____ of its welding heat on the work, and about ____ on the tungsten
2/3 1/3
Inverter welders may have transformers as light as
7lbs
What can be done to counteract the loss of certain alloying elements such as chromium, vanadium, aluminum, titanium, manganese or silicon
Add a deoxidizer to the filler wire
The amount of heat produced by a welding arc is determined by
Amperage
_____. Controls the size of the arc
Amperage
The unit of measure of electrical flow is
Amps
The positive side of an electrode arc is called
Anode
High frequency maybe set so that it____ for DC and ____ for AC
Automatically cuts off after the arc is established; is kept on continuously
Why is the travel and work angle important?
Because of the jetting force of the electrode end
Students will find it easier to start with
Butt joints
Flowmeters measure flow rate of a shielding gas in... units
CFH or L/min
Too light of a feed roller pressure can
Cause erratic wire feeding
____ electrodes have a current carrying capacity similar to that of pure tungsten and may be used for both AC and DC welding currents
Cerium tungsten
A(n) ______ Is a large piece of metal used to absorb excessive heat
Chill plate
The more cost efficient welders can be, the more ______ They and their companies become
Competitive
Shielding gases in the gas metal arc process are used primarily to protect the molten metal from oxidation and...
Contamination
The useful life of a ceramic nozzle is affected by the
Current level and proximity to the work
Shielded metal arc welding machine's voltage output _____ as its current ______.
Decrease Increases
Filler metals and fluxes usually have ________ added to them so that the adverse effects of the mill scale are reduced or eliminated
Deoxidizers
Electrodes have forceful arc with little slag left on weld bead
E6010 and E6011
Rutile-based fluxes with a thick slag left on the weld bead
E6012 and E6013
Electrodes have a mineral based flux with very heavy slag left on the weld bead
E7016 and E7018
A(n) _____ joint is made by placing the edges of the plates together evenly with no gap between the plates
Edge
What may happen if too short of an arc length is used
Electrode may stick to the plate
When CO2 is being used as a shielding gas and the voltage is set near maximum..
Excessive spatter may occur
Perpendicular Welding gun angle produces welds that
Have a good balance between penetration and reinforcement
Which of the following is an inert gas
Helium
With ____, penetration and bead profile are sensitive to arc length, and the long arcs needed for feeding filler wires are more difficult to control.
Helium
_______ is a byproduct of the natural gas industry. It is removed from natural gas as the gas undergoes separation for purification or refinement
Helium
Any benefit to mill scale that can be found on almost all hot rolled steel?
Help to prevent rust from forming
Overfilling a molten weld pool will result in drips of metal called ________________
Icicles
Is true of grinding tungsten electrodes?
If the grinder is used for metals other than tungsten, particles of these metals may become trapped on the tungsten as it is ground, resulting in contamination when the arc is started
