Welding Dictionary

There are no products matching the selection.

   Select the first letter of the term you are looking for:

        A C D F G H I K M O P R S T V W



Alternating Current (AC)

The reversal of an electrical currents direction at regular intervals, adjustability controlled by an AC Frequency Control on Longevity AC TIG welders.


The measurement of how much electricity flowing past a given point in a conductor per second. Current can be another name for amperage.  


The gap between the end of the tip on the torch (on a plasma cutter or the electrode rod of a welder)/ and and the base metal. The physical gap causes heat from the resistance of current flow and the arc rays.  



Also known as amperage. The amount of electricity flowing past a given point in a conductor per second.  



One or more impurity's and/or flaws in a weld that cause a testing failure.  


Also known as Arc Control. This gives a power source additional variable amperage during low voltage (short arc length) conditions while welding. This helps protect you from 'sticking' your stick electrodes when a short arc length is used.  

Direct Current (DC)

A current that flows in one direction and does not alternate its current path.  

Direct Current Electrode Negative (DCEN

(DCSP). The direction that the current flows through a welding circuit when the electrode lead is connected to the negative post and the work lead is connected to the positive post of a DC welding machine.  

Direct Current Electrode Positive (DCEP)

(DCRP). The direction that the current flows through a welding circuit when the electrode lead is connected to a positive post and the work lead is connected to a negative post to a DC welding machine.  

Duty Cycle

The percentage out a 10 minute time period that a welding machine can be ran at full amperage. Example would be 50% duty cycle at 60 amps. This would mean that at 60 amps the welding machine can be used for 5 minutes and then must be allowed to cool with the fan motor running for 5 minutes.  


Flexible Automation

Automated robotically controlled welding system that can perform complex shapes and applications where the welding paths require torch-angle manipulation.  

Flux Cored Arc Welding (FCAW)

An arc welding process which melts and joins metals by heating them with an arc between a continuous, consumable electrode wire and the work. Shielding is obtained from a flux contained within the electrode core. Added shielding may or may not be provided from externally supplied gas or gas mixture.


Gas Metal Arc Welding (GMAW)

Sometimes referred to by its subtypes metal inert gas (MIG) welding or metal active gas (MAG) welding, is a semi-automatic or automatic arc welding process in which a continuous and consumable wire electrode and a shielding gas are fed through a welding gun. A constant voltage, direct current power source is most commonly used with GMAW, but constant current systems, as well as alternating current, can be used. There are four primary methods of metal transfer in GMAW, called globular, short-circuiting, spray, and pulsed-spray, each of which has distinct properties and corresponding advantages and limitations.

Gas Tungsten Arc Welding (GTAW)

also known as tungsten inert gas (TIG) welding, is an arc welding process that uses a non-consumable tungsten electrode to produce the weld. The weld area is protected from atmospheric contamination by a shielding gas (usually an inert gas such as argon), and a filler metal is normally used, though some welds, known as Autogenous welds, do not require it. A constant current welding supply produces energy which is conducted across the arc through a column of highly ionized gas and metal vapors known as a plasma.

Ground Connection

A safety connection from a welding machine frame to the earth. Please see work piece for the difference between your work connection and ground connection.

Ground Lead

Your ground wire connection that attaches from the machine to the work piece. Also known as the work lead.



Hertz is often referred to as "cycles per second". In the United States, the frequency or directional change of alternating current is usually 60 hertz.

High Frequency

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



Power source which increases 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.


KVA (Kilovolt-amperes)

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

KW (Kilowatts)

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. Kilowatts are found by taking volts x amps divided by 1,000 and taking into account any power factor.



One or more integrated circuits that can be programmed with stored instructions to perform a variety of functions.

MIG Welding (GMAW or Gas Metal Arc Welding)

welding process which joins metals by heating them with an arc. The arc is between a continuously fed filler metal (consumable) electrode and the work piece. Externally supplied gas or gas mixtures provide shielding.

There are four basic metal transfer modes:


Short Circuit Transfer  Gets its name from the welding wire actually 'short circuiting'(touching) the base metal many times per second. Some spatter is produced, but the transfer can be used in all welding positions and on all thicknesses of metal.


Globular Transfer Named for globs of weld metal transferring across the arc in a gravity feed. Droplets across the arc are usually larger than the electrode diameter. It does not produce a very smooth weld bead appearance, and some spatter can occur. Usually limited to the flat and horizontal welding positions, and not used on thin metals.


Spray Transfer - Named for a spray of tiny molten droplets across the arc, usually smaller than the wire diameter. Uses relatively high voltage and amperage values, and the arc is on at all times after the arc is established. Very little if any spatter is produced. Usually used on thicker metals in the flat or horizontal welding positions.


Pulsed-Spray Transfer  For this variation of spray transfer, the welding machine pulses the output between high peak currents and low background currents. The weld pool gets to cool slightly during the background cycle, making it slightly different than Spray Transfer. This can allow for welding in all positions on either thin or thick metals.



Open-Circuit Voltage (OCV)

As the name implies, no current is flowing in the circuit because the circuit is open. The voltage is impressed upon the circuit, however, so that when the circuit is completed, the current will flow immediately.


Pilot Arc Automatic Restart

Automatically restarts the pilot arc when cutting through expanded metal or multiple pieces of metal, without having to re-press the trigger. This is included on our ForceCut LP-60I IGBT Plasma Cutter and our Weldall PI line of IGBT machines.

Plasma Arc Cutting

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

Pounds Per Square Inch (psi)

A measurement equal to a mass or weight applied to one square inch of surface area.

Power Efficiency

How well an electrical machine uses the incoming electrical power.

Power Factor Correction

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

Primary Power

Often referred to as the input line voltage and amperage available to the welding machine from the shop's main power line. Often expressed in watts or kilowatts (KW), primary input power is AC and may be single-phase or three-phase.

Pulsed MIG (MIG-P)

A modified spray transfer process that produces no spatter because the wire does not touch the weld puddle. Applications best suited for pulsed MIG are those currently using the short circuit transfer method for welding steel, 14 gauge (1.8 mm) and up

Pulsed TIG (TIG-P

A modified TIG process appropriate for welding thinner materials.


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


Rated Load

The amperage and voltage the power source is designed to produce for a given specific duty cycle period.

Resistance Spot Welding (RSW)

A process in which two pieces of metal are joined by passing current between electrodes positioned on opposite sides of the pieces to be welded. There is no arc with this process.

RMS (Root Mean Square)

The "effective" values of measured AC voltage or amperage. RMS equals 0.707 times the maximum, or peak value.


Semiautomatic Welding

The equipment controls only the electrode wire feeding. The welding gun movement is controlled by hand.

Shielded Metal Arc Welding

Shielding Gas

Protective gas used to prevent atmospheric contamination of the weld pool.

Single-Phase Circuit

An electrical circuit producing only one alternating cycle within a 360 degree time span.


The metal particles blown away from the welding arc. These particles do not become part of the completed weld.

Spot Welding

Usually made on materials having some type of overlapping joint design. Can 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 one side only.

Stick Welding (SMAW or Shielded Metal Arc)

arc welding rocess which melts and joins metals by heating them with an arc, between a covered metal electrode and the work. Shielding gas is obtained from the electrodes outer coating, often called flux. Filler metal is primarily obtained from the electrode core.

Submerged Arc Welding (SAW)

A process by which metals are joined by an arc or arcs between a bare metal electrode or electrodes and the work. Shielding is supplied by a granular, fusible material usually brought to the work from a flux hopper.


Three-Phase Circuit

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

TIG Welding (GTAW or Gas Tungsten Arc)

Often called TIG welding (Tungsten Inert Gas), this welding process joins metals by heating them with a tungsten electrode which should not become part of the completed weld. Filler metal is sometimes used and argon inert gas or inert gas mixtures are used for shielding.

Trigger Reset

Permits quick reset at gun rather than at machine.

Touch Start

A low-voltage, low-amperage arc starting procedure for TIG (GTAW). The tungsten is touched to the workpiece; when the tungsten is lifted from the workpiece an arc is established.


Rare metallic element with extremely high melting point (3410o Celsius).



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

Voltage-Sensing Wire Feeder

Feeder operates from arc voltage generated by welding power source.

Volt-Amp Curve

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


Weld Metal

The electrode and base metal that was melted while welding was taking place. This forms the welding bead.

Weld Transfer

Method by which metal is transferred from the wire to the molten puddle.


Unburned fuel and engine oil collecting in the exhaust stack of a diesel engine, characterized by the exhaust stack being coated with a black, sticky, oily substance. The condition is caused by the engine being run at too light of a load for extended periods of time. Caught early, this does not cause permanent damage and can be alleviated if additional load is applied. If ignored, permanent damage can occur to the cylinder walls and piston rings.

Wire Feed Speed

Expressed in in/min or mm/s, and refers to the speed and amount of filler metal fed into a weld. Generally speaking the higher the wire feed speed, the higher the

Workpiece Connection

A means to fasten the work lead (work cable) to the work (metal to be welded on). Also, the point at which this connection is made. One type of work connection is made with an adjustable clamp.

Workpiece Lead

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