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alternating current
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Current that regularly reverses the direction of its flow. AC is mostly limited to welding ferrous metals.
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ammeter
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A device that measures amperes in an electrical circuit. Some machines have built-in digital ammeters.
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amp
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A unit of measurement that indicates the amount of current flowing in a circuit. "Amp" is short for ampere.
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ampere
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A unit of measurement that indicates the amount of current flowing in a circuit. Arc welding uses high amperage.
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arc
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The area in which electricity jumps from the electrode to the workpiece. The heat generated by the arc melts the base metals.
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arc blow
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A condition that occurs when the arc does not follow its intended path from the electrode to the workpiece. Arc blow can cause undesirable weld beads.
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arc length
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The distance the arc stretches from the electrode to the workpiece. Longer arcs require more voltage.
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arc welding
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A fusion welding process that uses electricity to generate the heat needed to melt the base metals.
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atom
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The smallest distinguishable unit of a material that maintains the same characteristics of that material.
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base metal
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One of the two or more metals to be welded together to form a joint.
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bead
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The end product of a joint that has been welded.
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circuit
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A controlled path for electricity. A circuit includes a source, path, load, and control.
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conductor
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A material that allows for the flow of electricity. For a successful arc weld, electrodes and base metals must be good conductors.
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constant current
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Welding using a current that varies slightly with changes in voltage. Constant current, or CC, is often used in shielded metal arc welding (SMAW) and gas tungsten arc welding (GTAW).
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constant voltage
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Welding using a voltage that varies slightly with changes in current. Constant voltage, or CV, is often used for gas metal arc welding (GMAW) and flux-cored arc welding (FCAW).
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consumable electrode
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An electrode that conducts electricity to the arc but also melts into the weld as a filler metal.
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control
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The device that affects or alters the flow of current in a circuit. In arc welding, the control can turn the circuit on or off, and in most cases, adjust the voltage and amperage.
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current
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The rate and amount of electrical flow. Arc welding requires a continuous flow of electricity to maintain the arc.
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current output
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The maximum amount of current that a given welder can generate.
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direct current
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A current formed when electrons flow in one continuous direction. Many applications use DC current. Gas metal arc welding (GMAW) and flux-cored arc welding (FCAW) require DC.
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directly proportional
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A constant ratio between two values. If value A increases, value B also increases. If value A decreases then value B also decreases.
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duty cycle
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The amount of time in a ten-minute period that a welder can perform work without overheating. In the shop, welders with a higher duty cycle are preferred.
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electrical shock
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The flow of electricity through the human body. Electrical shock can be fatal.
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electricity
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The energy created by the movement of electrons. Electrical energy can be converted into light, heat, or motion.
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electrode
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A device that conducts electricity. In welding, the electrode also can act as the filler metal.
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electromotive force
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The force that pushes electrons through a conductor.
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electron
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A negatively charged particle that orbits the nucleus of an atom. Electrons move between atoms to cause electrical flow.
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energy efficient
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Not wasting electricity. Energy efficient devices do work using smaller amounts of electricity, which costs less.
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ferrous metal
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A metal that contains iron. Ferrous metals are the most common type of welded metal.
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filler metal
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A type of metal sometimes added to the joint in fusion welding. Filler metal adds to the strength and mass of the welded joint.
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flux
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A non-metallic material used to protect the weld puddle and solid metal from atmospheric contamination.
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flux-cored arc welding
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An arc welding process that uses a continuously fed consumable electrode that contains flux at its core. It is also referred to as FCAW.
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formula
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A general fact or principle that is expressed mathematically.
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gas metal arc welding
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An arc welding process in which the bare wire electrode and inert shielding gas are fed to the weld through a welding gun. It is also referred to as GMAW or MIG welding.
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gas tungsten arc welding
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A very precise arc welding process that uses a nonconsumable tungsten electrode. It is also referred to as GTAW or TIG welding.
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ground
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Safely connected to a neutral body, like the earth, which can absorb a stray electrical charge.
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heat distortion
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The undesirable physical change in a material due to excessive temperature changes.
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incomplete fusion
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Metals that have not been effectively welded together.
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insulator
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A material that inhibits the flow of electricity.
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inversely proportional
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A constant ratio between two values. If value A increases, then value B decreases. If value A decreases, then value A increases.
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inverter
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An energy efficient welder that is smaller than traditional welders, but has more electrical power.
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load
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The device that converts electricity into another form of energy, such as heat, light, or motion. In an arc welding circuit, the arc is the load.
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low-carbon steel
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A steel that has a carbon range between 1.05 and 0.30%. Also referred to as mild steel, low-carbon steel is the most commonly welded metal.
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melting rate
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The speed at which an electrode melts into the base metals. The melting rate of an electrode is a consideration when setting the voltage and amperage on a welder.
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neutron
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A particle with a neutral charge that is located in the nucleus of an atom.
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nonferrous metal
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A metal that does not contain iron. Nonferrous metals are more difficult to weld than ferrous metals.
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ohm
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A unit of measurement for electrical resistance.
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Ohm’s Law
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The law describing the relationship between voltage, amperage, and resistance. Ohm's Law states that volts equals amperes multiplied by ohms.
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path
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A conductor that directs electricity in a circuit. In welding, the path is often copper wire.
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penetration
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The distance below the surface of the base metals that the arc heat can melt the joint. The amount of current directly affects weld penetration.
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polarity
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The direction of current flow in a direct current (DC) circuit.
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porosity
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Unsightly gaps on the surface of the weld bead that form as a result of trapped gas during the welding process. Arc blow can cause porosity.
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power
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Work performed by electricity that appears in another form of energy such as heat, light, or motion.
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primary voltage shock
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An electrical shock from 120-480 volts that occurs in arc welding from touching a lead inside a switched-on welder and then touching the welder case or other grounded metal at the same time.
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proportional
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A constant ratio or relationship between two values. If one value changes, the other must change to maintain the same ratio.
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proton
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A particle with a positive charge that is located in the nucleus of an atom.
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reactor
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A device used in an electrical circuit that stabilizes and adjusts low voltage current into high amperage current.
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rectifier
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A device used in an electrical circuit that converts AC power to DC power.
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resistance
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The opposition to current flow. Electricity flows in the path of least resistance.
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reverse polarity
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Current in arc welding that flows from a negative workpiece to a positive electrode. Reverse polarity creates more heat at the electrode.
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secondary voltage shock
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An electrical shock from 60-100 volts that occurs in arc welding from touching the electrode while another part of the body touches the workpiece.
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self-regulated
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A term used to describe the arc in constant voltage arc welding applications. A change in arc length with CV welders automatically adjusts the electrode melting rate.
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shielded metal arc welding
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An arc welding process that uses a flux-coated rod. It is also referred to in the shop as SMAW or stick welding.
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source
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The device that supplies the current that flows throughout a circuit. A welder is an example of a source.
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spatter
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Liquid metal droplets expelled from the welding process. Spatter can leave undesirable dots of metal on a workpiece surface.
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straight polarity
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Current in arc welding that flows from a negative electrode to a positive workpiece. Straight polarity creates more heat at the workpiece.
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transformer
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A device used in an electrical circuit that reduces the voltage of incoming electrical power.
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undercut
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A gap left in a finished weld that should have been filled with weld metal. Undercut is unsightly but does not necessarily indicate a bad weld.
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vaporize
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The process by which a liquid becomes a gas. Vaporization of a metal can ruin a weld.
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volt
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A unit of measurement that indicates the degree of electrical pressure or potential.
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voltage
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The electrical force or pressure that causes current to flow in a circuit. Arc welding uses low voltage.
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voltmeter
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A device that measures the voltage in a electrical circuit. Some welders have built-in digital voltmeters.
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watt
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A unit of measurement that indicates the amount of electrical power in a circuit.
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wattage
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The amount of electrical power required by a device to work properly. For example, light bulbs are categorized by their required wattage.
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welder
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Either the person who performs a weld or the power source that provides the electricity needed to perform an arc weld. Printed materials may use both meanings of the term.
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work cable
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The path used in welding to conduct electricity from the welder to the workpiece. In welding, the cables are connected to the welder, the workpiece, and electrode, providing a closed electrical circuit.
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work clamp
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The component that, along with the electrode, comes in direct contact with the workpiece during welding. The work clamp is connected to the work cable.
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workpiece
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A part that is being worked on. The workpiece may be subject to cutting, welding, forming, or other operations.
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