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Welding Dictionary



The minimum distance between the weld root and weld face.

Air-Carbon Arc Cutting (Cac-A)

A cutting process of an arc, by which metals are melted by the heat using a carbon electrode. Molten metals are forced away by a blast of forced air.


A mixture composed of more than one elements,of which at least one is a metal.

Automatic Welding

Equipment that Welds without adjusting the controls constantly. automatic sensing device is used for adjusting the controls. Shortly weld made by equipments like robots

Arc Blow

The deflection from its normal path of an electric welding arc due to some magnetic forces in the base metal.

Arc Cutting

Cutting processes in which the cutting of metals is done by melting with the heat of an arc between the electrode and the base metal..

Arc Welding

Welding processes in which metal fusion is obtained by heating with an electric arc, using the filler metal is optional..


A physical gap between the end of an electrode and base metal. This gap causes heat due to resistance


Measuring the amount of electricity flowing through a given point in a conductor per second. Amperage is nothing but current.

Auto-Link (MTE)

Internal inverter power source circuit that automatically links the power sour ce to the primary voltage being applied. It does not need manually linking primary voltage terminals.


Bead Weld

A type of weld composed of one or more string beads deposited on an surface

Base Metal

The metal to be welded, brazed, soldered, or cut. In alloys, it is the largest proportion.

Butt Joint

Joining two metals in such a manner that the weld joining the parts is between the surface planes of both metal pieces.

Butt Weld

A weld joining two metals laying in the same plane. A weld in a butt joint.


Constant Current (CC) Welding Machine

CC welding machines have limited maximum short circuit current. They have a negative volt-amp curve and are often referred to as “droopers”. The voltage will change with different arc lengths with slight variation in amperage, thus the name constant current or variable voltage.

Constant-Speed Wire Feeder

Feeder works from 24 or 115 VAC supplied by the welding power source

Constant Voltage (CV), Constant Potential (CP) Welding Machine

CV and CP welding machine output maintains a relatively stable, consistent voltage without considering the amperage output. It results in a relatively flat volt-amp curve as opposed to the drooping volt-amp curve of a typical Stick (SMAW) welding machine. “Potential” and “voltage” are basically same.


Also called amperage. The amount of electricity flowing through a point in a conductor every second.


A weld that drops under the intended perpendicular plane.



One or more discontinuities that cause the weld or part unable to meet minimum acceptance standards or criteria of the design specifications.

Direct Current (DC)

Current flows in one direction from negative to positive (Cathode to Anode) and does not reverse its direction of flow as alternating current.

Direct Current Electrode Negative (DCEN)

Current flowing out of the welding Rod or Wire is dispersed into the work piece ,therefore giving less penetration. About 1/3 of the heat is on the end of the rod and 2/3 on the work piece.

Direct Current Electrode Positive (DCEP)

Current flowing into the welding Rod or Wire and therefore putting more heat at the rod or wire end. This gives you 2/3 heat on the rod and 1/3 on the work piece, which gives greater penetration for thick metals because the arc force digs into the steel before depositing filler metal.

Duty Cycle

The percentage of time a machine can run in a ten minute period of time before it overheats.
10% = 1 minute out of every 10.
20% = 2 minutes out of every 10.
On up to 100% which would run the full time without stopping. For a machine in a factory or construction site you’d want a 100% duty cycle


Edge Joint

Joining the edges of two or more parallel members.

Edge Preparation

Before welding the edge of a plate or pipe, care is taken to ensure a sound weld. It may be torch cut, machined with a grinder, filed, or all three.


Electrodes are either covered with flux, or just bare wire. In the field an electrode is called a “rod” in stick welding, and “wire” for Mig and Flux Cored Arc Welding.



Internal power source cooling system that only works when needed, to keep internal components cleaner.

Fixed Automation

Automated, electronically controlled welding system for simple, straight or circular welding.

Flexible Automation

Automated, robotically controlled welding system used for complex shapes and applications where welding require torch-angle manipulation.

Flux Cored Arc Welding (FCAW)

An arc welding process which melts and welds metals by heating them with an arc between a continuous, consumable electrode wire and the work. Shielding is attained from a flux contained within the electrode core. Depending upon the type of flux-cored wire used added shielding may or may not be provided from externally supplied gas or gas mixture. Consumables: contact tips, flux cored wire, shielding gas (if required, depends on wire type).


Ground Connection

A safety connection between a welding machine frame and the earth. Often used for grounding an engine-driven welding machine where a cable is connected from a ground stud on the welding machine to a metal placed in the ground.

Gas Metal Arc Welding (GMAW)

An arc welding process in which metal fusion is produced by the heat of an arc between a continuous filler metal electrode and the work piece with externally supplied shielding gas. GMAW-P (pulse arc) and GMAW-S (short arc) are variations of this method.

Gas Tungsten Arc Welding (GTAW)

A gas shielded arc welding method in which the heat is produced using a non-consumable tungsten electrode to transfer the arc to the work piece.



Hertz is referred as “cycles per second”.

High Frequency

Covers the high frequency spectrum above 50,000 Hz. Used in TIG welding for arc ignition and stabilization.

Hot Start

Used in some Stick (SMAW) machines to make it easier to start difficult-to-start electrodes. Used for arc starting only.



Power source which raises the frequency of the incoming primary power, thus providing for a smaller size machine and improved electrical characteristics for welding, such as faster response time and more control for pulse welding.



Intersection where two different sections of base metal meet.


KVA (Kilovolt-amperes)

The total volts times amps divided by 1,000, demanded by a welding power source from the primary power supplied by the utility company.

KW (Kilowatts)

A kilowatt is volts times amps divided by 1,000 and taking into account any power factor. Primary KW is the actual power used by the power source when it is producing its rated output. Secondary KW is the actual power output of the welding power source.



Allows TIG arc starting without high frequency. Starts the arc at any current without contaminating the weld with tungsten.

Lap Joint

Joining two overlapping metal parts by means of a fillet, plug or slot weld.



One or more integrated circuits that are programmed with stored instructions to perform varies functions.

MIG (GMAW or Gas Metal Arc Welding)

Also referred to as solid wire welding. It is an arc welding process in which fusion of metals is by heating them with an arc. The arc is between a continuously fed filler metal (consumable) electrode and the work piece. Shielding is provided by externally supplied gas or gas mixtures.

Common MIG welding is referred to as short circuit transfer. Metal is deposited only when the wire actually touches the work piece. No metal is transferred across the arc.

Another method of MIG welding spray transfer, it moves a stream of tiny molten beads across the arc from the electrode to the weld puddle. Consumables: contact tips, shielding gas, welding wire

Melting Rate

The weight or length of the rod (electrode) melted in a unit of time.

Melting Point

The temperature at which a metal starts to liquefy.



Metals not from iron ore. Aluminum, brass, bronze, copper, lead, nickel, and titanium are nonferrous metals.


Open-Circuit Voltage (OCV)

No current will flow in the circuit because the circuit is open. The voltage is impressed upon the circuit, however, so that when the circuit is closed, the current will flow immediately. For example, a welding machine that is turned on but not being used for welding at the moment will have an open-circuit voltage.


Plasma Arc Cutting

An arc cutting process which cuts metal by using a thin arc to melt a small area of the work. This process can cut all metals that conduct electricity.

Pounds Per Square Inch (psi)

Measurement of a mass or weight applied to one square inch of surface area.

Power Efficiency

 How efficiently an electrical machine uses the incoming electrical power.

Power Factor Correction

Usually used on single-phase, constant current power sources, to reduce the amount of primary current demanded from the power company while welding.

Primary Power

Often referred to as the input line voltage and current available to the welding machine from the shop’s main power line. It is expressed in watts or kilowatts (KW), primary input power is AC and may be single-phase or three-phase. Welding machines with the capability of accepting more than one primary input voltage and current must be properly connected for the incoming primary power being used.

Pulsed MIG (MIG-P)

A modified spray transfer process that produces no spray because the wire does not touch the weld puddle. Currently using short circuit transfer method for welding steel, 14 gauge (1.8 mm) and up are best suited for pulsed MIG . Consumables: contact tips, shielding gas, welding wire.

Pulsed TIG (TIG-P)

A modified TIG welding process suitable for welding thinner materials. Consumables: tungsten electrode, filler material, shielding gas.


Sequencing and controlling the amount of current, the polarity, and the duration of the welding arc process.


Rated Load

The amperage and voltage of the power source is designed for producing a given specific duty cycle period. For example, 300 amps, 32 load volts, at 60% duty cycle.

Resistance Spot Welding(RSW)

A process in which two metal pieces are joined by passing current between electrodes positioned on opposite sides of the pieces to be welded. There is no arc in this process, and the resistance of the metal to the current flow causes the fusion. Spot welding requires the following equipment: air- or water-cooled spot welder, set of 2 tongs and set of 2 tips. Consumables are not required to spot weld.


Root Mean Square. The “effective” values of measured AC voltage or current RMS equals 0.707 times the maximum, or peak value.


Semiautomatic Welding

The welding machine operates the wire (FILLER METAL) and supplies the SHEILDING GAS automatically, but it needs a person to pull the trigger and control the gun to make the weld. MIG is an example.

Shielding Gas

 Gases which prevents atmospheric contamination of the weld puddle. Examples are some inert gases: argon or helium.

Single-Phase Circuit

 An electrical circuit generating only one alternating cycle within a 360 degree time period.


The metal particles excluded during arc and gas welding. These particles do not form a part of the finished weld.

Spot Welding

Employed in some materials having some type of overlapping joint design. Refer to resistance, MIG or TIG spot welding.
Resistance spot welds are made from electrodes on both sides of the joint, while TIG and MIG spots are made from electrodes on one side only.

Shielded Metal Arc Welding (SMAW)

Also known as stick welding. This welding process uses a powder coated rods or electrodes placed in a holder that is arced against the base metal.


TIG Welding (GTAW or Gas Tungsten Arc Welding)

TIG (Tungsten Inert Gas), this welding process combines metals by heating them with a tungsten electrode which should not become part of the completed weld. Filler metal is at times used and argon inert gas or inert gas mixtures are used as shielding gas. Consumables: tungsten electrode, filler metal, shielding gas.

Three-Phase Circuit

An electrical circuit transporting three cycles within a 360 degree time period, and the cycles are 120 electrical degrees apart.


A device used in the TIG welding (GTAW) process to manage the position of the electrode, to transfer current to the arc, and to direct the flow of the shielding gas.

Touch Start

A low-voltage, low-amperage arc starting procedure for TIG welding (GTAW). The tungsten is contacted to the work piece; when the tungsten is lifted away from the work piece an arc is established.


Rare metallic element with extremely high melting point (3410o Celsius). Used for manufacturing TIG electrodes.

Tack Weld

A small weld made to hold parts of a welding work piece in proper way until the final welds are made.



Channels melted into the base metal adjacent to the toe or root of a weld and left unfilled by weld metal.


An undesirable crater at the edge of the weld caused by poor weaving technique or extreme welding speed.


A localized increase in volume in the part of a weld, resulting by the application of pressure.

Upsetting Force

The force applied at the welding surfaces in flash or upset welding.



Pressure or energy that pushes the electrons through a conductor. Voltage does not flow, but causes current to flow. Voltage is sometimes called electromotive force (EMF) or difference in potential.

Voltage-Sensing Wire Feeder

Feeder that operates from arc voltage produced by welding power source.

Volt-Amp Curve

Graph that illustrates the output characteristics of a welding power source. Shows voltage and amperage capacity of a specific machine.


Weld Metal

The electrode and base metal that is melted during welding.

Weld Transfer

Method by which metal is changed from the wire to the molten puddle. Several methods are used in MIG welding; they are: short circuit transfer, spray arc transfer, globular transfer, buried arc transfer, and pulsed arc transfer.

Wire Feed Speed

Refers to the speed and quantity of filler metal fed into a weld and it is expressed in mm/s or in/min. Generally the higher the wire feed speed, the higher the amperage.

Workpiece Connection

A way to fasten the work lead (work cable) to the work (metal to be welded on). Also, the point at which the connection is made. One type of work connection is made with a modifiable clamp.

Workpiece Lead

The conductor cable or electrical conductor which is between the arc welding machine and the work.



A radiographic test method used to detect internal faults in a weld.