GMAW/FCAW Final Flashcards
Gas Metal Arc Welding
GMAW-S
Short Circuiting Transfer
encompasses the lowest range of welding currents and electrode diameters associated with the GMAW process. This process produces a fast freezing weld pool that is generally suited for joining thin sections, out-of- position welding, or root passes
Gas Metal Arc Welding
GMAW-MSC
Modified Short Circuit
has several proprietary derivatives of the short-circuiting transfer mode which use a modified waveform to reduce some of the problems found with short- circuiting—mainly, spatter and a turbulent weld pool. Typically these systems sense the progression of the short circuit as it happens and modulates the current to limit the amount of force behind spatter and turbulence-producing events.
Gas Metal Arc Welding
GMAW-MSC (Modified Short Circuit)
Power Supply:
power sources are software-driven to maintain optimum arc characteristics by closely monitoring and controlling the electrode current during all phases of the short-circuit.
What’s the primary purpose of shielding gas?
Prevents the molten weld metal from absorbing elements from atmospheric air such as oxygen and nitrogen
What is the lightest gas?
Hydrogen
Metal transfer
The manner in which molten metal transfers from the end of the electrode across the welding arc to the weld pool.
pulsed spray transfer (GMAW-P)
A variation of spray transfer in which current is pulsed from a low background level to a peak level above the spray transfer transition current.
contact tip-to-work distance (CTWD)
The distance from the end of the contact tip to the work and includes arc length.
short circuiting transfer (GMAW-S)
A metal transfer mode in which molten metal from consumable welding wire is deposited during repeated short circuits.
Electrode extension
The distance from the contact tip to the end of the welding wire.
Globular transfer
The transfer of molten metal in large droplets from a welding wire across an arc to a workpiece.
Spray transfer
A metal transfer mode in which molten welding wire is propelled axially across an arc.
Burn back
A condition that occurs when welding wire is restricted and fuses to the end of a contact tip.
gas metal arc welding (GMAW)
An arc welding process that produces an arc between a continuous wire electrode and a workpiece, creating a weld pool in the presence of a shielding gas.
Intermediate weld pass
A single progression of welding subsequent to the root pass and before the cover pass.
Washing
A process of removing metal from large areas, such as the removal of surfacing metal, backing material, or riser pads on castings.
Arc plasma
A gas that is superheated to an ionized condition, enabling it to conduct an electric current.
Kerf
The gap produced by a cutting process.
air carbon arc cutting (CAC-A)
A group of cutting processes that use heat generated by an oxyfuel gas flame.
Gouging
A cutting process that removes metal by melting or burning the entire removed portion to form a bevel or groove.
plasma arc cutting (PAC)
A cutting process that uses a constricted arc to remove molten metal with a high-velocity jet of arc plasma (ionized gas) issued from a constricting orifice.
Viscosity
The resistance of a substance to flow in a fluid or semifluid state.
Ultrasonic welding (USW)
A welding process that produces a weld by applying high-frequency vibratory energy to workpieces that are held together under pressure.
Background current
a relatively low amperage used to maintain the arc during pulsed spray transfer GMAW
an alternate term for constant voltage
Constant potential
an electrode that melts and becomes part of the weld
Consumable electrode
Drive rolls
the rolls in a were drive unit that are directly driven by the units drive motor
Flow meter
a device that controls the amount of gas that goes to the welding torch
flux cored arc welding (FCAW)
a welding method in which heat is supplied by an arc between the base metal and a hollow, flux-filled electrode.
Gas metal arc welding (GMAW)
an arc welding process that uses a continuously fed consumable electrode and a shielding gas. Sometimes called MIG Welding
Globular transfer
in GMAW, the movement of molten metal in lare droplets from the consumable electrode across the arc
Helium
an inert, colorless gas used as a shielding gas in welding
Type of welding machine used for GMAW
Inverter
Liner
a flexible tube placed inside the combination cable through which a consumable wire electrode passes on its way to the GMAW torch
Common term for Gas Metal Arc Welding (GMAW)
Metal inert gas
Metal transfer
movement of metal from one surface to another
Pulsed spray transfer
a GMAW process in which the current is pulsed to take advantage of the spray mode of metal transfer, but with current values below the spray transition current
Purge switch
a switch on a welding machine that manually controls the flow of shielding gas
Push-pull system
a system formed when a GMAW pull gun pulls the electrode wire through the cable and the wire feeder pushes the wire
Self-shielded electrode
an electrode that produces its own shielding gas and does not require additional shielding gas
Short circuit transfer
a GMAW process that uses relatively low voltage. The arc is constantly interrupted and restarted as the molten electrode shorts out against the base emtal
Transfer-rectifier
one type of constant voltage rectifier
Wire feeder
in GMAW, the device that continuously feeds consumable electrode wire to the welding gun.
Wire tension control knob
the device used to control the pressure applied to the drive rolls of a wire feeder
Regulator
a device used to control the volume and pressure of a welding or shielding gas as it flows from the cylinder to the torch
most effective current for GMAW because it produces deep penetration
DCEP
GMAW power source
DC - direct current
_____ is directly related to arc length
Voltage
contact tip-to-work distance
the distance from the end of the contact tip to the work and includes arc length
Gs diffuser
distributes gas evenly around the welding wire and contact tip
Gas nozzle
directs the flow of shielding gas to the molten weld
Insulator
prevents the gas nozzle from becoming energized; reduces heat transfer from the gas nozzle to the conductor tubes
Wire feed speed control
Adjusts the speed with which welding wire feeds the arc
Voltage control
Allows the welder to set optimum arc length
Purge button
allows welder to set the shielding gas flow rate without using the gun trigger; used to purge gas line in the welding gun cable before welding
Axially
In a straight line along an axis
Composite metal-core wire electrode
A filler wire electrode with a hollow core containing powdered materials, primarily metals.
Stick out
The length of electrode that projects from the contact tube, measured from the arc tip to the contact tube.
Name the 5 basic pieces of equipment required for GMAW
- welding power source
- wire feeder compatible with machine
- welding gun
- spooled filler wire
- shielding gas
Gun and cable assemblies are rated by…
Their current rated capacity
What is the job of a regulator?
A regulator reduces the gases from source pressure to a working pressure.
What does amperage control?
Burn off and penetration
What is the main purpose of slope?
To limit the short circuiting current so spatter is reduced.
Very fine droplets of metal transferred across the arc in a axial fasion, describes what mode of metal transfer?
Spray transfer
When using GMAW, an increase in the arc voltage produces what?
Wider arc stream and shallower penetration
What must be considered before using a mini-bulk system?
Frequency of use
Spray transfer employs higher:
Voltage settings
Recommended power source for FCAW
DC
CV
What’s the purpose of the electrode (wire) feed control?
To supply the continuous electrode to the welding arc at a constant preset rate
Gas shielding equipment includes:
Gas source
Pressure regulator
Flowmeter
All necessary hoses and connectors
Most common metals to weld on using FCAW
- Mild steels
- High strength steel
- Chrome-molybdenum steel
- stainless steel
- abrasive resistant steel
- cast steels
- nickel alloys
Electrode classification for FCAW:
E 7 0 T - X M J HZ
Designate each one…
E-electrode
70-tensile strength
T-indicates electrode is FCAW
X-refers to usability of electrode
M-indicates electrode is classified using 75-80% argon/balance CO2
J-requirements for improved toughness
HZ-requirements of diffusible hydrogen test
Travel speed
The linear rate at which the arc is moved along the weld joint
GMAW Advantages
- Can weld all commercial metals
- All position welding
- Deposition rates are higher
- Faster travel speeds
- Continuous welds
- Minimal post-weld cleaning
GMAW limitations
The equipment required for GMAW is more…
- costly - complex - less portable
Limited outdoor use
The modes of metal transfer for GMAW are:
Short-circuiting transfer
Globular transfer
Spray transfer
The mode of transfer is determined by:
- Magnitude, type and polarity of welding current
- electrode diameter
- electrode composition
- electrode extension
- shielding gas composition
GMAW-S
Short-circuiting transfer
Metal transfer results when molten metal from a consumable electrode is deposited during repeated short-circuits
GMAW wire packaging and delivery systems consist of:
Spools
Coils w/ support
Coils w/o support
Drums
A filler metal packaging configuration in which the wire is wound around a cylinder (called a barrel), which is flanged at both ends. The flanges contain a spindle hole centered side the barrel.
Spool
GMAW electrodes packaging sizes include:
2 lb
13 lb
44 lb
A cylindrical filler metal package used to contain a continuous length of wound or coiled filler metal wire.
Drum
Delivery systems used in heavy industry consisting of a separate location for electrode storage components and extended liners (hose packs) to deliver the electrode to the wire feed rolls.
Bulk electrode system
Recommended wire sizes for welding thin materials:
.023 - .035 inches
CV welding power sources for GMAW can be:
Transformer-rectifiers or inverters
An increase in voltage will produce…
A flatter, wider bead
Excessive voltage can cause problems with…
Burnback
CV power sources are designed to…
Maintain selected arc voltage
Electrode extension
Is the distance from the contact tip to the end of the welding wire.
Welding gun cable…
Conducts the welding wire, shielding gas and current to the gun
Gun cable liner
Serves as a conduit for the welding wire
Welding gun components include:
Contact tip
Nozzle
Diffuser
Insulator
Diffuser
Distributes shielding gas evenly around the welding wire and contact tip
Nozzle
Directs the flow of shielding gas to molten weld
Insulator
Prevents nozzle from becoming energized
Ire feed speed control
Adjusts the speed with which welding wire feeds the arc.
Voltage control
Allows a the welder to set the optimum arc length
Purge button
Allows welder to set shielding gas flow rate w/o using the gun
Most common wire feeder for steel welding wire is the…
Push type wire feeder
Shielding gas affects the properties of…
The weld deposit
