Chapter 17 GMAW and FCAW Flashcards
What does FCAW stand for and which welding techniques are used for FCAW?
- Flux cored arc welding
- Primarily performed using backhand method or with the gun nearly vertical
What does GMAW stand for and which welding techniques are used for GMAW?
- Gas metal arc welding
- backhand, forehand and with the gun held vertically
The _____________ method pulls or drags the weld pool along the weld axis.
backhand
In backhand welding, the tip of the electrode points opposite _______________
the direction of travel
Backhand welding uses a travel angle of about ______°. It is also called a _______ angle.
25°
drag
In backhand welding, the electrode can be held perpendicular to the workpiece which means the travel angle is _____°
0°
The ______ welding method pushes the weld pool. The tip of the electrode points ____________.
- forehand
- in the direction of travel
The forehand welding travel angle is called a ______ angle. The electrode and gun form a travel angle of about _____°.
push
25°
The backhand welding method is used too obtain better ___________ than forehand or vertical.
penetration
______________ method has a more stable arc and produces less spatter than the other tow methods.
backhand
When welding, which should you do first: position the gun, or tilt the gun?
You should position the gun over the area where you will begin welding. Tilt the gun to obtain the desired travel angle.
Increasing the voltage produces a ___________ weld pool.
wider, flatter weld pool
What would happen if you set the voltage too high?
It would cause porosity and excessive spatter
_____________the voltage produces a narrower and sometimes excessive reinforcement or buildup.
lowering
What would happen if you set the voltage too low in GMAW?
It can cause the electrode to short to the weld pool
What does increasing the voltage do?
Increases pool width
Some welders use a small oval motion when welding the root pass of a ___________ or __________ weld.
groove or fillet
After checking the equipment, a welder must consider which four factors before selecting an electrode and shielding gas?
- What type of base metal is to be welded
- How thick the base metal is
- In what position will the welding be done?
- What type of metal transfer will be used?
In GMAW and FCAW, the __________ determines the arc length.
voltage set on the welding machine
In GMAW and FCAW, the wire feed speed determines the _____________.
current
What is the contact tube-to-work distance?
The distance from the contact tube to the surface of the work
What is electrode extension?
It is the distance from the end of the contact tube to the end of the electrode. It is also known as electrode stick-out
How is electrode extension controlled?
The welder must control it
What is the electrode extension for GMAW using short circuiting?
1/4” - 1/2’ (6mm - 13 mm)
What is the electrode extension for GMAW using spray transfer?
1/2” - 1” (13 mm- 25 mm)
What is the electrode extension for FCAW using gas-sheilding?
3/4” - 1 1/2” (19 mm - 38 mm)
What is the electrode extension for FCAW using self-sheilding?
3/4” - 3 3/4” (19mm - 95 mm)
Why can’t the contact tube be seen while welding?
Because it is inside the nozzle
Because the contact tube can’t be seen, the welder uses _______________ to control the contact tube-to-work distance.
nozzle-to-work
What is nozzle-to-work distance?
the distance from the end of the nozzle to the base metal.
A _________ weld is started in the same manner as a weld bead on a plate. The electrode and arc are centered over the _________.
fillet
weld root
In a fillet weld, the welding gun should be held at about a _______° work angle to the base metal.
45°
What positions should the gun be held for a fillet weld?
backhand, forehand or perpendicular.
Once a welding arc is started, a pool will instantly develop under the arc. Some ____________ movement of the gun may be required to initially form a __________ weld pool.
side-to-side
c-shaped
______V is an appropriate voltage to weld carbon steel using a 0.035” electrode and short circuiting transfer.
20V
What gas mixture is recommended to weld 308 stainless steel using spray transfer?
Argon with 1% oxygen
Wire feed guns are generally rated by their _________________
current carrying capacity
