Welding Processes and Equipment Review

Flashcards testing terminology, equipment components, polarity, drive rolls, and process parameters for Shielded Metal Arc Welding (SMAW), Gas Metal Arc Welding (GMAW), Flux Cored Arc Welding (FCAW), and Gas Tungsten Arc Welding (GTAW).

Shielded Metal Arc Welding (SMAW)

Also known as "stick welding", a manual welding process that uses a flux-coated consumable electrode to produce an electric arc and form a weld protected by slag.

Gas Metal Arc Welding (GMAW)

Also known as "MIG welding", an arc welding process that uses a continuously fed solid wire electrode and an external shielding gas to protect the weld pool from atmospheric contamination.

Flux Cored Arc Welding (FCAW)

An arc welding process that utilizes a continuous tubular wire electrode containing flux within its core to provide shielding and alloying elements.

Gas Tungsten Arc Welding (GTAW)

Also known as "TIG welding", an arc welding process that uses a non-consumable tungsten electrode and an inert shielding gas to produce high-quality, precise welds.

Oxyacetylene Welding

A gas welding process that mixes oxygen and acetylene to generate a high-temperature flame used to melt the base metal and filler rod.

Direct Current Electrode Positive (DCEP)

Also known as reverse polarity, a direct current setup where current flows from the base metal to the electrode, generating $70\%$ of the heat at the electrode and $30\%$ at the base plate.

Direct Current Electrode Negative (DCEN)

Also known as straight polarity, a direct current setup generating $1/3$ of the heat at the electrode and $2/3$ at the base plate, resulting in lighter penetration and a wider, shallower weld pool.

Heat Distribution Diagram in Welding Polarity

A visual comparison of heat distribution across polarities: DCEN yields $1/3$ heat at the tip and $2/3$ at the plate; DCEP yields $2/3$ heat at the tip and $1/3$ at the plate; AC splits heat evenly ($1/2$ and $1/2$).

Duty Cycle

The percentage of time that a welding machine can safely operate at a specific amperage within a $10\text{--}minute$ time period without overheating.

Pound Per Square Inch (PSI)

A standard unit of pressure measurement used in welding regulators to quantify high-pressure gases inside cylinder tanks.

Cubic Feet Per Minute (CFM)

A unit measuring airflow volume based on how many cubic feet of air pass a stationary point in one minute, with standard GMAW shielding gas rates set between $18\text{--}20\,\text{CFM}$ and a maximum of $30\,\text{CFM}$.

Flowmeter

A device connected to a gas cylinder used to control and measure the precise volume rate of shielding gas delivered to the workpiece.

Welding Regulator

A control device attached to a gas cylinder used to reduce high cylinder pressure down to a safe, usable working pressure.

Wire Feeder

A motorized drive mechanism responsible for feeding the continuous wire electrode from the spool through the gun assembly at a controlled speed.

GMAW/FCAW Gun Assembly

The handheld welding torch containing the gun body, insulated conductor tube, conduit liner, gas diffuser, gun trigger, contact tip/tube, and gas nozzle.

Contact Tip

A replaceable copper nozzle located inside the gas nozzle that guides the wire electrode and transfers electrical current to it.

Gas Nozzle

A metal cup surrounding the contact tip that directs shielding gas evenly over the weld pool and protects internal torch components.

Gas Diffuser

A perforated brass component inside the gun torch that holds the contact tip and spreads shielding gas into a uniform stream.

Conduit / Liner

A flexible metal sleeve installed inside the gun cable assembly whose sole purpose is to guide the welding wire from the feeder to the contact tip.

Gun Trigger

The control switch on the welding torch that, when depressed, initiates wire feeding, electrical power, and shielding gas flow simultaneously.

U-Groove Drive Roll

A type of drive roll featuring smooth, U-shaped grooves, designed specifically for small-diameter, soft wires or soft-shelled cored wires that flatten easily.

V-Knurled Drive Roll

A drive roll with knurled V-grooves used for hard-shelled cored wires and wire sizes $1/16\,\text{in}$ ($1.6\,\text{mm}$) and larger to prevent wire slippage.

U-Cogged Drive Roll

A geared drive roll set with teeth cut into both rolls, used to drive large-diameter or extremely soft flux-cored wires without crushing them.

Fume Extractor

An exhaust mechanism attached near the weld zone or gun assembly to capture smoke and gases produced by flux-cored electrodes, enhancing visibility and air quality.

Slag

A non-metallic layer formed over the weld bead when flux coating or core materials melt, acting to protect the cooling metal from atmospheric contamination.