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Welding Terminology

Alternating Current (AC) - An electrical current that reverses its direction at regular intervals, such as 60 cycles alternating current (AC), or 60 hertz.

Amperage - The measurement of the amount of electricity flowing past a given point in a conductor per second. Current is another name for amperage.

Arc -The physical gap between the end of the electrode and the base metal. The physical gap causes heat due to resistance of current flow and arc rays.

Arc Force - Also called Dig and Arc Control. Gives a power source variable additional amperage during low voltage (short arc length) conditions while welding. Helps avoid "sticking" stick electrodes when a short arc length is used.

Auto-Link ® - Internal inverter power source circuit that automatically links the power source to the primary voltage being applied, without the need for manually linking primary voltage terminals.

Automatic Welding - Uses equipment which welds without the constant adjusting of controls by the welder or operator. Equipment controls joint alignment by using an automatic sensing device.

Constant Current (CC) Welding Machine - These 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 while only slightly varying the amperage, thus the name constant current or variable voltage.

Constant-Speed Wire Feeder - Feeder operates from 24 or 115 VAC supplied by the welding power source.

Constant Voltage (CV), Constant Potential (CP) Welding Machine - "Potential" and "voltage" are basically the same in meaning. This type of welding machine output maintains a relatively stable, consistent voltage regardless of 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.

Current - Another name for amperage. The amount of electricity flowing past a point in a conductor every second.

Defect - One or more discontinuities that cause a testing failure in a weld.

Direct Current (DC)-Flows in one direction and does not reverse its direction of flow as does alternating current.

Direct Current Electrode Negative (DCEN) - The specific direction of current flow through a welding circuit when the electrode lead is connected to the negative terminal and the work lead is connected to the positive terminal of a DC welding machine. Also called direct current, straight polarity (DCSP).

Direct Current Electrode Positive (DCEP) - The specific direction of current flow through a welding circuit when the electrode lead is connected to a positive terminal and the work lead is connected to a negative terminal to a DC welding machine. Also called direct current, reverse polarity (DCRP).

Duty Cycle -The number of minutes out of a 10-minute time period an arc welding machine can be operated at maximum rated output. An example would be 60% duty cycle at 300 amps. This would mean that at 300 amps the welding machine can be used for 6 minutes and then must be allowed to cool with the fan motor running for 4 minutes. (Some manufacturers rate machines on a 5 minute cycle).

Fan-On-Demand TM - Internal power source cooling system that only works when needed, keeping internal components cleaner.

Fixed Automation - Automated, electronically controlled welding system for simple, straight or circular welds.

Flexible Automation - Automated, robotically controlled welding system for complex shapes and applications where 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. Depending upon the type of flux-cored wire, 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 from a welding machine frame to 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 stake placed in the ground. See Work piece Connection for the difference between work connection and ground connection.

Ground Lead - When referring to the connection from the welding machine to the work, see preferred term Work piece Lead.

Hertz - 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 for arc ignition and stabilization.

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

Inverter - 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. 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 times amps divided by 1,000 and taking into account any power factor.

Lift-ArcTM - This feature allows TIG arc starting without high frequency. Starts the arc at any amperage without contaminating the weld with tungsten.

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

MIG (GMAW or Gas Metal Arc Welding) - An arc 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. Common MIG welding is also referred to as short circuit transfer. Metal is deposited only when the wire actually touches the work. No metal is transferred across the arc. Another method of MIG welding, spray transfer moves a stream of tiny molten droplets across the arc from the electrode to the weld puddle. Consumables: contact tips, shielding gas, welding wire.

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. For example, a welding machine that is turned on but not being used for welding at the moment will have an open-circuit voltage applied to the cables attached to the output terminals of the welding machine.

Plasma Arc Cutting - An arc cutting process which severs metal by using a constricted arc to melt a small area of the work. This process can cut all metals that conduct electricity. Miller Spectrum cutters are complete packages that contain all required equipment and torch consumables. Consumables: torch consumables, gas or compressed air supply.

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. Welding machines with the capability of accepting more than one primary input voltage and amperage must be properly connected for the incoming primary power being used.

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. Consumables: contact tips, shielding gas, welding wire.

Pulsed TIG (TIG-P) - A modified TIG process appropriate for welding thinner materials. Consumables: tungsten electrode, filler material, shielding gas.

Pulsing - Sequencing and controlling the amount of current, the polarity, 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. For example, 300 amps, 32 load volts, at 60% duty cycle.

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, and it is the resistance of the metal to the current flow that 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.

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.

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.

Spatter - 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.

Squarewave TM - The AC output of a power source that has the ability to rapidly switch between the positive and negative half cycles of alternating current.

Stick Welding (SMAW or Shielded Metal Arc) - An arc welding process 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 electrode outer coating, often called flux. Filler metal is primarily obtained from the electrode core. An AC/DC welder is recommended for Stick. For most applications, DC reverse polarity welding offers advantages over AC, including easier starts and out-of-position welding, smoother arc and fewer arc outages and sticking. Consumables: stick electrodes.

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. Filler metal comes from the electrode and sometimes from a second filler rod.

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. Consumables: tungsten electrode, filler metal, shielding gas.

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

Torch - A device used in the TIG (GTAW) process to control 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 (GTAW). The tungsten is touched to the work piece; when the tungsten is lifted from the work piece an arc is established.

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

Voltage - 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. There are several methods used in MIG; they include: short circuit transfer, spray arc transfer, globular transfer, buried arc transfer, and pulsed arc transfer.

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 amperage.

Work piece 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.

Work piece Lead - The conductor cable or electrical conductor between the arc welding machine and the work.