Introduction to FCAW 261
Introduction to FCAW provides a comprehensive overview of the flux-cored arc welding (FCAW) process and its equipment. FCAW is divided into two types: self-shielded flux-cored arc welding (FCAW-S) and gas-shielded flux-cored arc welding (FCAW-G). Both FCAW-S and FCAW-G use a consumable, tubular electrode that is filled with flux materials. FCAW equipment includes a constant voltage power source, wire electrode, wire feeder, welding gun, and, if appropriate, a shielding gas.
Understanding the basic theory and process of FCAW is essential to using it successfully. After taking this class, users will be familiar with FCAW equipment and be able to distinguish between the different methods of FCAW. Users will also be able to identify the performance characteristics, operating requirements, and finished weld properties of FCAW electrodes. This information provides the foundation necessary to perform FCAW successfully and safely.
Number of Lessons 21
- Arc Welding
- Flux-Cored Arc Welding
- Self-Shielded FCAW
- Self-Shielded FCAW: Advantages and Disadvantages
- Gas-Shielded FCAW
- Gas-Shielded FCAW: Advantages and Disadvantages
- FCAW Processes Review
- FCAW Electrode Core Materials
- FCAW Electrode Construction
- Electrode Classification
- Electrode Storage and Handling
- FCAW Electrodes Review
- FCAW Equipment
- Self-Shielded FCAW Guns
- Gas-Shielded FCAW Guns
- FCAW Equipment Review
- Constant Voltage Power Sources
- Current and Polarity
- Types of Power Sources
- FCAW Safety
- Final Review
- Describe arc welding.
- Describe flux-cored arc welding.
- Describe self-shielded FCAW.
- Describe advantages and disadvantages of FCAW-S.
- Describe gas-shielded FCAW.
- Describe advantages and disadvantages of FCAW-G.
- Describe the purposes an FCAW electrode's core materials serve.
- Describe the construction of FCAW electrodes.
- Identify FCAW electrodes based on the AWS classification system.
- Describe storage and handling considerations for FCAW electrodes.
- Describe common equipment used in FCAW.
- Describe self-shielded FCAW guns.
- Describe gas-shielded FCAW guns.
- Describe constant voltage power sources.
- Describe current and polarity requirements of FCAW.
- Distinguish between different power sources used for FCAW.
- Describe common safety precautions for FCAW.
Alternating current. Current that reverses direction at regularly recurring intervals of time. In the United States, AC reverses 60 times per second, or 60 hertz.
A type of welding gun that uses air or gas as a coolant. Air-cooled guns have a small nozzle on the end to provide the air or gas.
A material that is intentionally added to a metal in order to change its properties. Alloying elements can improve the strength, ductility, hardness, and toughness of a finished weld.
AC. Current that reverses direction at regularly recurring intervals of time. In the United States, alternating current reverses 60 times per second, or 60 hertz.
A device that converts mechanical energy into AC energy. An alternator can provide electrical energy to a power source.
American Welding Society
AWS. The non-profit organization that regulates industrial standards for welding. The American Welding Society also promotes the welding industry in the United States.
The amount of current flowing in a circuit. Amperage is determined by wire feed speed (WFS) in FCAW.
The distance that electricity must travel from the tip of the electrode to the weld puddle. Longer arc lengths require more voltage.
A measure of a welding arc's consistency and predictability. Arc stability is essential during the welding process.
A joining process that uses an electric arc to melt metals and fuse them together permanently. Arc welding processes include shielded metal arc welding (SMAW), gas metal arc welding (GMAW), flux-cored arc welding (FCAW), and gas tungsten arc welding (GTAW).
Ar. An inert gas commonly mixed with carbon dioxide for use as a shielding gas. Argon is much heavier than air, so it effectively shields the weld area.
A type of welding process in which a computer or a robot controls both the welding equipment and the weld variables. In automatic welding, the welder is responsible for setting and controlling the specialized settings for the computer or robot.
American Welding Society. The non-profit organization that regulates industrial standards for welding. The AWS also promotes the welding industry in the United States.
Metals that are welded together to form a joint. The base metal and its properties influence the type of welding and the type of electrode that should be used.
CO2. An active gas that is heavy, colorless, and odorless. Carbon dioxide is commonly used as a shielding gas.
A common metal group that is an alloy of iron and carbon. The amount of carbon in a carbon steel affects its strength, ductility, and malleability.
The type, amount, and arrangement of atoms that, when combined, compose a whole material or substance. Chemical composition can be altered whenever a change occurs at the atomic level.
A controlled path for electricity. All arc welding processes require a closed electrical circuit that includes a source, path, load, and control.
An environment in which the temperature and humidity are strictly regulated. Climate-controlled environments are ideal for storing FCAW electrodes.
A material that can quickly catch fire if it comes in contact with sparks or fire. Combustible materials catch fire at higher temperatures than flammable materials.
An electrode made of more than one metal. Composite electrodes are identified with a "C" in the AWS electrode classification system.
CV. A power supply that maintains a consistent voltage while compensating for changes in amperage. Constant voltage is used in FCAW processes.
An electrode that conducts electricity to the arc but also melts into the weld as filler metal. Some consumable electrodes may also provide shielding that protects the arc and weld puddle.
The device located inside the welding gun that conducts electricity to the electrode. The contact tip is usually made of copper.
Any foreign substance that may cause a loss of efficiency or a breakdown. Contaminants in welds include oxygen and nitrogen.
A reddish metal that is very ductile, thermally and electrically conductive, and corrosion resistant. Copper is used to make the contact tips of welding guns.
A metal consisting of a mixture of copper and two or more other elements. Common copper alloys include aluminum-silicon-copper-magnesium and zinc-aluminum-copper-magnesium.
The inner part of an electrode that is surrounded by an outer metal sheath. The core of FCAW electrodes contains flux materials.
The ability of a material to resist deterioration and chemical breakdown due to surface exposure in a particular environment. Corrosion resistance is an important physical property of finished welds.
The flow of electricity through a circuit. Current is measured in amperes (A), or amps, and controls the heat of the arc.
Direct current. Current that flows in one continuous direction. DC is required for several common welding processes such as GMAW and FCAW.
An irregularity in the specified and expected composition of a weld that exceeds the part design's tolerances. A defect is an unacceptable discontinuity.
A material that removes nitrogen from the molten weld puddle. Denitrifiers prevent nitrogen from ruining a weld bead.
The amount of material within a specific volume. Objects with greater density have a relatively large amount of weight compared to the amount of physical space they occupy.
A material that removes oxygen from the molten weld puddle. Deoxidizers prevent oxygen from ruining a weld bead.
The rate at which filler metal is deposited into the molten weld puddle to form a weld. The deposition rate can be measured in pounds per hour (lb./hr) or in grams per minute (g/min).
A character or collection of characters that specifies an electrode's characteristics and properties in the AWS classification system. Designators can be mandatory or optional.
The maximum amount of hydrogen, given in milliliters (mL), that will be present per 100 grams of weld metal. An electrode's classification may specify its diffusible hydrogen.
DC. Current that flows in one continuous direction. Direct current is required for several common welding processes such as GMAW and FCAW.
direct current electrode negative
DCEN. Current that always flows in one continuous direction from the negative electrode to the positive workpiece. Direct current electrode negative polarity is also known as straight polarity, but this is a nonstandard term.
direct current electrode positive
DCEP. Current that always flows in one continuous direction from the negative workpiece to the positive electrode. Direct current electrode positive polarity is also known as reverse polarity, but this is a nonstandard term.
A constant relationship between two values. If values A and B are directly proportional, value A increases whenever value B increases, and value A decreases whenever value B decreases.
An irregularity in the specified and expected composition of a weld. A discontinuity is not always a defect.
A tool used to form wire or metal into a specified shape. Drawing dies reduce an FCAW electrode's diameter and compress its core materials during fabrication.
A set of wheels that moves electrode wire through a wire feeder. Drive rolls are specially designed for various types and sizes of electrodes and can be either smooth or knurled.
The amount of time in a ten-minute period that an electrical device can perform work before it must rest to prevent overheating. Duty cycle ratings are given as a percentage of the ten-minute period.
The area in which electricity jumps from an electrode to a workpiece. Electric arcs produce extreme heat and light.
The flow of electricity through the body. Electric shock can be fatal.
A force that opposes the flow of electrical current and can also affect voltage. Electrical resistance creates heat, which can be used for welding.
A device that conducts electricity in an electrical circuit. Electrodes can also serve as filler metal in some arc welding processes.
The path used in arc welding to conduct electricity from the power source to the electrode. The electrode cable connects the power source to the wire feeder or to the gun.
electrode efficiency rates
The percentage of a welding electrode that becomes filler metal. A higher electrode efficiency rate indicates a lower amount of electrode lost due to spatter or wasted as unusable stubs.
The distance from the end of the contact tip to the end of the electrode. The insulated guide on a welding gun can help control electrode extension.
The insulated lining that surrounds the electrode and supports it from the wire feeder to the contact tip in a welding gun. Electrode liners are made of coiled steel wire and can be either permanent or interchangeable.
Having an energy output that is close to the total energy supplied. Energy efficient devices do work using smaller amounts of electricity, which costs less.
engine-driven power source
A welding machine that converts mechanical energy from an engine into electrical energy. Engine-driven power sources may include alternators that allow them to run both AC and DC.
The process of creating parts by forming, reshaping, and assembling raw materials. Fabrication processes are usually more complicated than manufacturing processes.
Flux-cored arc welding. A semi-automatic or automatic arc welding process that uses a continuously fed consumable electrode with an inner core of flux. FCAW includes both self-shielded flux-cored arc welding (FCAW-S) and gas-shielded flux-cored arc welding (FCAW-G).
Gas-shielded flux-cored arc welding. A type of FCAW that uses a flux-filled, tubular wire electrode and an external shielding gas to protect the weld area. FCAW-G processes provide double shielding.
Self-shielded flux-cored arc welding. A type of FCAW that relies on the flux materials within a tubular wire electrode to provide shielding for the weld area. FCAW-S processes do not require external shielding gas.
A metal that contains iron. Ferrous metals are the most common type of welded metal.
Metal deposited into the weld that often adds strength and mass to the welded joint. The electrode provides the filler metal in some arc welding processes.
A portable device that uses a rapid spray of chemicals to put out small fires. Fire extinguishers are an essential part of fire prevention.
Made of materials that are designed to resist burning and withstand heat. Fire-resistant materials are essential to welding safety.
fixed classification system
An AWS numbering system that uses a set of standard designators to classify FCAW electrodes. The fixed classification system uses designators to indicate an electrode's tensile strength, weld position, type, usability, and shielding gas requirements.
A material that can quickly catch fire if it comes in contact with sparks or fire. Flammable materials catch fire at lower temperatures than combustible materials.
A device that indicates the volume of gas flowing to the weld area. The flowmeter connects to a valve that controls the amount of gas flow.
A nonmetallic material used to protect the weld puddle and arc from atmospheric contamination. In FCAW, flux material is contained in the core of the electrode.
flux-cored arc welding
FCAW. A semi-automatic or automatic arc welding process that uses a continuously fed consumable electrode with an inner core of flux. Flux-cored arc welding includes both self-shielded flux-cored arc welding (FCAW-S) and gas-shielded flux-cored arc welding (FCAW-G).
A chemical process that cleans and purifies the weld metal. Fluxing reactions occur when flux material vaporizes and combines with the weld metal.
Any device that uses suction to remove gases from the environment. Fume extractors are also called hoods.
A cloud-like area above the arc containing welding gases, metallic fumes, and particulates. Welders must keep their heads out of the fume plume and use adequate ventilation.
A metal container that stores shielding gases. Gas cylinders are built specifically for each gas and have different properties depending on the gas.
A device inside a welding gun through which shielding gas flows. The gas diffuser regulates the flow of gas.
A flexible tube used to deliver shielding gas. Gas hoses run from the gas cylinder to the wire feeder or welding gun.
An FCAW discontinuity that occurs when a gas bubble from the arc becomes trapped in the weld puddle and marks the weld bead after the slag solidifies. Gas marking, also called worm tracking, is more common with FCAW-G than FCAW-S.
gas metal arc welding
GMAW. An arc welding process in which a bare wire electrode and shielding gas are fed to the weld through a welding gun. Gas metal arc welding is also sometimes referred to as MIG or MAG welding, but these terms are nonstandard in the United States.
A device in a welding gun that forces shielding gas to surround the electrode and arc. The gas nozzle is placed directly over the contact tip and gas diffuser in a welding gun.
FCAW-G. A type of FCAW that uses a flux-filled, tubular wire electrode and an external shielding gas to protect the weld area. Gas-shielded FCAW processes provide double shielding.
gas-shielded flux-cored arc welding
FCAW-G. A type of FCAW that uses a flux-filled, tubular wire electrode and an external shielding gas to protect the weld area. Gas-shielded flux-cored arc welding processes provide double shielding.
A device that converts mechanical energy to electrical energy, producing DC. Generators use mechanical devices like engines and motors to generate electricity.
A type of tight-fitting eye protection that completely covers the eyes, eye sockets, and surrounding facial area. Goggles offer protection from impact, dust, chips, and splashes.
Steel that is raw and untreated. Green steel rods and strips are used in the FCAW electrode fabrication process.
A metal piece on an FCAW-S gun that protects the welder's hand from the excessive amount of slag and spatter produced during FCAW-S. The hand shield is located over the trigger on the gun.
A controlled heating and cooling process. Heat treatment changes the structure of a material and alters its physical and mechanical properties.
A plain carbon steel that contains more than 0.45% carbon. High-carbon steels are extremely strong and hard, and they always require heat treatment for effective welding.
Any device that uses suction to remove gases from the environment. Hoods are also called fume extractors.
H. A colorless, odorless gas that is the most abundant element on the planet. Hydrogen exposure can cause weld metal to crack.
A weld defect that occurs when hydrogen comes into contact with the weld metal. Low-hydrogen electrodes reduce hydrogen cracking.
Electricity from an electrical distribution system that supplies power to electrical equipment. Input voltage for welding power sources is higher than the voltage used during arc welding.
A threaded copper part that is attached to the end of the main tube of an FCAW-S gun. Insulated guides protect the end of the gun from becoming electrically charged and help maintain proper electrode extension.
A type of gas nozzle with an integrated piece of non-conductive material that prevents it from becoming electrically charged. Insulated nozzles are more expensive than slip-on nozzles.
A non-conductive material that prevents the flow of electricity. Insulators are used to prevent certain parts of the FCAW gun from becoming electrically charged.
A device designed to increase the frequency of electrical current. Inverters allow power sources to operate at higher frequencies.
inverter power source
A welding machine that runs in constant current and constant voltage modes with variable frequencies and amplitudes. Inverter power sources are energy efficient.
A process that brings materials together. Joining methods include fastening, adhesive bonding, and welding.
A surface that has been marked with small diamond-shaped impressions. Knurled drive rolls are able to more easily grip FCAW electrodes without deforming them.
A steel that contains small amounts of intentionally added materials that change the properties of the metal. Low-alloy steels commonly include manganese, molybdenum, and nickel.
A plain carbon steel that contains less than 0.30% carbon. Low-carbon steels are generally tough, ductile, and easily welded.
A substance used to prevent friction between two surfaces in relative motion. Lubricants reduce resistance, wear, and heat.
A type of welding process in which the welder controls all welding variables. Shielded metal arc welding (SMAW) is an example of a manual process.
A characteristic that determines a material's ability to compress, stretch, bend, scratch, dent, or break. The mechanical properties of a material describe the way the material responds to forces.
A plain carbon steel that contains between 0.30% and 0.45% carbon. Medium-carbon steels are strong, hard, and not as easily welded as low-carbon steels.
The rate at which metal melts off the electrode. The melt-off rate is measured in pounds per hour (lb./hr) or grams per minute (g/min).
A hard, silvery-white metal that is strong and corrosion resistant. Molybdenum can add toughness, creep strength, and wear resistance to alloys.
An electric charge with a surplus of electrons. A negative charge is often symbolized by a minus (-) sign.
open classification system
An AWS numbering system that uses optional designators in addition to fixed classification designators to further classify FCAW electrodes. The open classification system includes designators such as improved toughness and diffusible hydrogen.
O. A colorless, odorless, tasteless gas that naturally exists in the atmosphere. In welding, too much oxygen causes cracking and rusting in the metals.
The depth to which the arc heat melts the joint below the surface of the base metals. Penetration is directly affected by the amount of amperage.
The ratio of the weight of an electrode's core compared to the electrode's total weight. Percent fill can vary based on the materials included in the electrode's core and their density.
personal protective equipment
PPE. Any clothing or device worn to minimize exposure to hazards and prevent injury. Personal protective equipment for welding usually includes a welding helmet, jacket, safety glasses, and gloves.
A characteristic of a material that affects the way it performs a task. Physical properties describe the way a material responds to external environment conditions, such as temperature, chemical exposure, corrosion, and electricity.
Having two oppositely charged poles, one positive and one negative. Polarity determines the direction in which current flows.
A weld discontinuity characterized by the appearance of tiny voids or bubbles on a weld bead, resulting from trapped gases in a material. Excessive porosity can weaken a weld.
An electric charge with a shortage of electrons. A positive charge is often symbolized by a plus (+) sign.
pounds per square inch
psi. A unit of pressure used in the English system. Pounds per square inch measures the amount of load pressure that is applied over an area of one square inch.
The device that provides the electricity needed to perform arc welding. Power sources can be plugged into wall outlets or use mechanical devices such as motors or generators to produce electricity.
The device that indicates the amount of shielding gas present in a gas cylinder. The pressure gauge detects the level of gas pressure and displays it on a dial.
A container designed to hold liquids or gases at high pressures. Pressure vessels include gas canisters.
The relationship between two quantities. Ratios can be expressed as a fraction or as two numbers separated by a colon.
The process of repairing or restoring something. Reconditioning welding electrodes can include baking them in a special oven at a specific temperature for a designated length of time.
A device used in an electrical circuit that converts alternating current (AC) to direct current (DC). Rectifiers are sometimes used with transformers in welding power sources.
Protective eyeglasses with metal or plastic frames and impact-resistant lenses that may or may not offer vision correction. Many safety glasses also have protective side shields.
A material that cleanses and purifies the weld puddle while it is still in a molten condition. Scavenging elements can help improve the quality of the finished weld.
FCAW-S. A type of FCAW that relies on the flux materials within a tubular wire electrode to provide shielding for the weld area. Self-shielded FCAW processes do not require external shielding gas.
self-shielded flux-cored arc welding
FCAW-S. A type of FCAW that relies on the flux materials within a tubular wire electrode to provide shielding for the weld area. Self-shielded flux-cored arc welding processes do not require external shielding gas.
A type of welding process in which the power source maintains a uniform arc and a wire feeder controls the electrode. In semi-automatic welding, the welder is responsible for controlling the position of the welding gun as well as the direction and speed of travel.
A case or covering that usually encloses a tubular structure. In FCAW electrodes, a metal sheath surrounds a flux core.
shielded metal arc welding
SMAW. An arc welding process that uses a flux-coated rod as its electrode. Shielded metal arc welding is also called stick welding or manual welding.
A gas that protects the weld puddle and arc from reacting negatively with the atmosphere. Shielding can be provided by an external supply of gas or by a type of flux materials.
A gas that protects the weld puddle and arc from reacting negatively with the atmosphere. External shielding gas is supplied by a cylinder and flows through the welding gun.
Cooled flux that forms on top of the weld bead. Slag protects cooling metal and is then chipped off.
A weld discontinuity resulting from the combined dissolution of flux and nonmetallic impurities. Slag inclusions can affect the strength and integrity of a finished weld.
A type of gas nozzle that consists of separate insulator and nozzle components. Slip-on nozzles are less expensive than insulated nozzles.
Shielded metal arc welding. An arc welding process that uses a flux-coated rod as its electrode. SMAW is also called stick welding or manual welding.
Liquid metal droplets expelled from the welding process. Spatter can leave undesirable dots of metal on a workpiece surface.
A cylindrical device used for storing, winding, and unwinding welding electrodes. Spools are used in semi-automatic and automatic welding processes.
spray arc transfer
A type of metal transfer in which the filler metal at the end of the electrode melts into small, fine droplets. Spray arc transfer creates a stable arc and little spatter.
A group of steels that contains a minimum of 10.5% chromium. Stainless steel is very hard and exhibits excellent corrosion resistance.
The ability of a material to resist forces that would otherwise break or deform it. There are different types of strength, including tensile, compressive, and shear strength.
A material's ability to resist forces that attempt to pull it apart or stretch it. Tensile strength is usually expressed in pounds per square inch (psi) or in kilopascals (kPa).
A connecting point in a circuit where a wire is attached to create an electrical connection. Terminals can be either positive or negative.
The ability of a metal to absorb energy without breaking or fracturing. Toughness is a key property because it determines the ability of a material to withstand a sudden stress.
A device that uses magnetic induction to transfer electrical energy from one circuit to another, without changing the frequency. Transformers are often used with rectifiers in welding power sources.
transformer power source
A welding machine that uses a transformer to supply electricity. Transformer power sources are comparatively inexpensive, but large and inefficient.
A device used to protect the valves on a gas cylinder. Valve caps are an important safety device.
Changes from a solid or liquid to a gas. Some of the flux material at an FCAW electrode's core vaporizes to create shielding and initiate fluxing reactions within the weld metal.
A means of providing fresh air. For the safety of the welder, welding requires proper ventilation.
The electrical force or pressure that causes current to flow in a circuit. Voltage is measured in volts (V).
A type of welding gun that uses water as a coolant. Water-cooled guns require external equipment to deliver the water.
The end product of a welded joint. Weld beads are formed using a variety of techniques.
The small area of molten metal that forms during welding. The cooled weld puddle forms the permanent joint.
A person who performs welding. Welders perform many arc welding processes.
A joining process that permanently bonds two separate components together. Welding uses heat, pressure, or a combination to make one new part.
A welding instrument that conducts electricity, guides the electrode, and, in some cases, releases shielding gas. Welding guns are used in some automatic and semi-automatic welding processes.
A protective eye and face covering worn during welding. The welding helmet protects the welder from the arc's harmful rays and intense bright light.
The position in which a welder performs a weld. Welding positions include overhead, vertical, flat, and horizontal.
wire feed speed
WFS. The rate at which the wire electrode is fed through the welding gun. Wire feed speed determines amperage and the amount of heat in the arc.
The device that feeds a supply of wire electrode to the welding gun. Wire feeders are either built inside or set beside the power source.
wire feeder welder
A small, self-contained welding unit that houses both the power source and a constant-speed wire feeder. Wire feeder welders are economical and good for performing light-duty FCAW.
The path used in arc welding to conduct electricity from the power source to the workpiece. The work cable attaches to the workpiece via the work clamp.
A component that connects the work cable to the workpiece. The work clamp helps form the welding circuit.
A part that is being worked on during manufacturing. The workpiece may be subject to cutting, welding, forming, or other operations.
An FCAW discontinuity that occurs when a gas bubble from the arc becomes trapped in the weld puddle and marks the weld bead after the slag solidifies. Worm tracking, also called gas marking, is more common with FCAW-G than FCAW-S.