Introduction to SMAW 252

“Introduction to SMAW” covers the basic theories and practices of shielded metal arc welding (SMAW), as well as common operational procedures. SMAW is a welding process that uses shielding to protect the weld from contamination. SMAW is one of the most common arc welding processes in the world because of its simplicity, versatility, affordability, and suitability for most applications. SMAW requires a range of specialized equipment, specific electrodes, and knowledge of a number of safety precautions.

After taking this course, users will know how to safely handle, prepare, and operate SMAW equipment. They will also have a basic understanding of how to perform an SMAW weld.

Class Details

Class Name:
Introduction to SMAW 252
Difficulty:
Intermediate
Number of Lessons:
19

Class Outline

  • Shielded Metal Arc Welding
  • Advantages and Disadvantages of SMAW
  • SMAW Equipment
  • SMAW Basics Review
  • Electrical Components
  • Electrical Components: Electricity Transfer
  • Electrode Composition
  • Types of Electrodes
  • Electrode Selection
  • Electrode Selection: Labels
  • Electrode Safety
  • SMAW Components Review
  • Current
  • Power Sources
  • Amperage
  • Voltage
  • Joint Preparation
  • SMAW Operation
  • Final Review

Objectives

  • Define SMAW.
  • List the advantages and disadvantages of SMAW.
  • Describe SMAW equipment.
  • Describe the electrical components of SMAW.
  • Describe the composition of an electrode.
  • Distinguish between the different types of electrodes.
  • Explain how to select an electrode.
  • Identify electrodes based on the AWS numbering system for electrode classification.
  • Describe how to safely handle and store electrodes.
  • Describe the current requirements for SMAW applications.
  • Describe the types of power sources used for SMAW applications.
  • Describe the amperage requirements of SMAW.
  • Describe the voltage requirements of SMAW.
  • Explain how to prepare joints for SMAW.
  • Describe the different operating steps of SMAW.

Job Roles

Certifications

Glossary

Vocabulary Term Definition
AC Alternating current. A current that regularly reverses the direction of its flow. In SMAW, it is preferable for power sources to generate both AC and DC to fit all applications.
alloys A metal consisting of a mixture of two or more materials. Stainless steel, for example, is an alloy of iron, carbon, and chromium.
alternating current AC. A current that regularly reverses the direction of its flow. In SMAW, it is preferable for power sources to generate both alternating current and direct current to fit all applications.
alternators 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 the industrial standards for welding. The American Welding Society also promotes the welding industry in the United States.
amperage A measurement that indicates the amount of current flowing in a circuit, which is measured in amperes or amps (A). Amperage in SMAW ranges between 10 to 500 amps.
amps A. A unit of measurement that indicates the amount of current flowing in a circuit. Amps are properly referred to as amperes.
arc The area in which electricity transfers from the electrode to the workpiece. The heat generated by the arc melts the base metals and filler metal during SMAW.
arc blow A condition that occurs when the arc does not follow its intended path from the electrode to the workpiece. Arc blow can cause excessive spatter, incomplete fusion, and porosity.
arc length The distance that electricity must travel from the electrode to the workpiece. Longer arc lengths require an increased level of voltage.
arc voltage The amount of voltage present between the electrode and the workpiece. For SMAW, arc voltage ranges from 14 to 45 volts.
AWS American Welding Society. The non-profit organization that regulates the industrial standards for welding. AWS also promotes the welding industry in the United States.
base metals Metals that are welded together to form a joint. In SMAW, the welder guides the electrode along the seam of the base metals to make a weld.
beveled edge An edge that is angled rather than perpendicular to the sides of an object. A beveled edge may be created by the welder in order to provide easier access to the weld when working with thicker materials.
burnthrough A discontinuity in which weld metal from one side of a joint melts through to the other. Burnthrough can leave an open hole in the joint, which must then be ground down and re-welded.
butt joints A type of joint between two metal parts that lie in the same plane. The butt joint is the most common type of joint.
calcium A nonmetallic material that is often present in the flux coating of an SMAW electrode. Calcium floats to the top of the molten weld pool and forms slag.
carbon A common nonmetallic element found in all types of steel. Carbon is added to the filler metal in an SMAW electrode to help strengthen the joint.
chipping hammer A tool used to scrape slag from a cooled weld bead. The chipping hammer is also known as a scaling hammer.
circuit A controlled path for electricity. All arc welding processes require a closed electrical circuit through which electricity can easily flow.
complete penetration A weld that extends completely through the thickness of the materials being joined. If complete penetration is required through one side of a joint, base metals may require weld backing.
conductor A material that allows electricity to flow easily. Conductors are coated in shielding materials to create SMAW electrodes.
constant current CC. A power supply that maintains a steady flow of current, regardless of fluctuations in voltage. SMAW applications require constant current power sources.
consumable electrode An electrode that conducts electricity to the arc but also melts into the weld as filler metal. SMAW consumable electrodes also provide shielding that protects the arc and weld pool.
convex Curving outward like the exterior surface of a circle or sphere. Fast-fill SMAW electrodes produce slightly convex weld beads.
cracking Fractures that develop in the weld after solidification is complete. Welds with high hardness are prone to cracking.
crater An undesirable depression in the weld bead. A crater can cause cracking if it is not properly filled.
current The flow of electricity through a circuit. Current is measured in amperes, or amps, (A) and controls the heat of the arc.
DC Direct current. A current that flows in one continuous direction. In SMAW, it is preferable for power sources to generate both AC and DC to fit all applications.
DC electrode negative DCEN. Direct current with straight polarity. DC electrode negative electricity flows from the negative electrode to the positive workpiece.
DC electrode positive DCEP. Direct current with reverse polarity. DC electrode positive electricity flows from the negative workpiece to the positive electrode.
deposition rate The rate at which filler metal melts off the electrode into the weld puddle. Deposition rate can be measured in pounds per hour or in grams per minute.
direct current DC. A current that flows in one continuous direction. In SMAW, it is preferable for power sources to generate both alternating current and direct current to fit all applications.
discontinuities An irregularity in the specified and expected composition of a weld, which may or may not be considered a defect. During SMAW, discontinuities are sometimes caused when a welder must stop and start welding to change the electrode.
electrode A device in an electrical circuit that conducts electricity. In SMAW, the electrode also acts as filler metal.
electrode cable The path used in welding to conduct electricity from the power source to the electrode. Electrode cables and work cables connect the power source, workpiece, and electrode to create a closed electrical circuit.
electrode holder The insulated handle that clamps onto the electrode. The electrode holder is connected to the power source during welding to control the arc.
electrode orientation The position in which the welder manipulates the electrode to create a weld bead. Electrode orientation refers to the work angle and travel angle.
engine-driven power sources A welding machine that converts mechanical energy from an engine into electrical energy. Engine-driven power sources obtain energy from gas or diesel engines.
fast-fill electrodes An SMAW electrode that fills a joint quickly due to the addition of iron powder in the flux. Fast-fill electrodes melt quickly and are ideal for large workpieces.
fast-freeze electrodes An SMAW electrode that solidifies quickly. Fast-freeze electrodes are ideal for overhead welding and correcting poor fit-up and gaps.
ferrous A metal that contains iron. Ferrous metals are the most common type of welded materials.
filler metal A metal that is added to a weld and has properties similar to those of the base metal. Filler metal often adds to the strength and mass of the welded joint.
fill-freeze electrodes An SMAW electrode that has both fast-fill and fast-freeze characteristics. Fill-freeze electrodes both fill a joint and solidify quickly.
fit-up The way mating parts fit together. Proper fit-up occurs when parts fit together without extra space or gaps.
flat-position welding The welding position used to weld from the upper side of the joint. In flat-position welding, the face of the weld is horizontal.
flux A nonmetallic material used to protect the weld pool and cooling metal from atmospheric contamination in some welding processes. SMAW uses electrodes that have flux-coated cores.
gaps An extra, undesirable space between mating parts. Gaps can be corrected by SMAW with a fast-freeze electrode.
generators A device that converts mechanical energy to electrical energy, producing DC. Generators use magnetic induction to convert energy.
horizontal-position welding A common welding position in which the weld is performed on the upper side of a horizontal surface and against a vertical surface. Horizontal-position welding is often used for fillet and groove welds.
incomplete fusion A weld discontinuity in which the weld metal and base metal or adjoining weld beads are not fully fused. Incomplete fusion significantly weakens the integrity of the weld.
inverter power sources A welding machine that runs in constant current and constant voltage modes with variable frequencies, amplitudes, and AC/DC output. Inverter power sources are energy efficient.
inverters A device designed to convert AC power to DC power. Inverters can quickly and easily switch between AC and DC electricity.
joint preparation Any process used to prepare base metals for welding. Joint preparation often includes preheating, cutting, or other processes.
low-hydrogen electrodes An SMAW electrode that is used to weld metals that are susceptible to cracking. Low-hydrogen electrodes are ideal for awkward positions.
magnetic induction The process of inducing current in a magnetic field using a current-carrying coil. A generator produces a current through magnetic induction.
manganese A hard, brittle, gray-white metal often added to electrodes. Manganese acts as a deoxidizer and increases strength and hardness in the weld.
manual welding An arc welding process that uses a flux-coated electrode. Manual welding is also referred to as shielded metal arc welding (SMAW) or stick welding.
mechanical energy A combination of kinetic and potential energy resulting from the force of gravity or the movement or release of a machine component, such as a spring, clamp, or wheel. Mechanical energy can be converted to electrical energy by a generator.
multi-process machines A welding power source that can provide most of the functions of different types of power sources. Multi-process machines can successfully complete a wide variety of welding processes.
nitrogen A colorless, odorless, tasteless gas that naturally makes up 78% of breathable air. Nitrogen can ruin a weld bead, so electrodes often contain elements to de-nitrify the molten metal.
nonferrous A metal that does not contain iron as a main ingredient. Common nonferrous metals include aluminum, titanium, copper, and nickel.
out-of-position Not in a classified or categorized welding position. Out-of-position welds are often done with electrodes that have smaller diameters to prevent spillage.
overhead-position welding Welding that is performed from the underside of a joint. Overhead-position welding requires extra safety precautions.
oxygen A colorless, odorless, tasteless gas that naturally exists in the atmosphere. A small amount of oxygen is sometimes used for shielding, but too much oxygen causes cracking, porosity, and rusting in the welded metals.
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.
polarity Having two oppositely charged poles, one positive and one negative. Polarity determines the direction in which current flows.
porosity A 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.
power source A device that supplies the electricity needed for arc welding. Power sources can be plugged into wall outlets or use a device, such as a motor or generator, to create electricity.
rectifiers A device used in an electrical circuit that converts AC into DC. Rectifiers are used with transformers in welding power sources.
scaling hammer A tool used to scrape slag from a cooled weld bead. The scaling hammer is also known as a chipping hammer.
scratching A method of striking the arc by quickly moving an electrode across the surface of a workpiece at an angle. The scratching method closely resembles striking a match.
seam The place where base metals meet or overlap. The welder guides the electrode along the seam to fuse metals together.
shielded metal arc welding SMAW. An arc welding process that uses a flux-coated electrode. Shielded metal arc welding is also referred to as stick welding or manual welding.
shielding A gas or type of flux that protects the weld pool and arc from atmospheric contamination. Shielding is provided by the material coating the electrode in SMAW processes.
short circuit A circuit in which current takes a shorter, unintended path between two conductors, interrupting the intended flow of electricity. Short circuits can damage equipment and can cause sparks or fire.
silicon A nonmetallic material that is often present in arc welding electrodes. Silicon acts as a deoxidizer.
slag Cooled flux that forms on top of the weld bead. Slag protects cooling metal and is then chipped off.
SMAW Shielded metal arc welding. An arc welding process that uses a flux-coated electrode. SMAW is also referred to as stick welding or manual welding.
spatter Liquid metal droplets expelled from the welding process. Spatter can leave undesirable dots of metal on the surface of a workpiece.
stick welding An arc welding process that uses a flux-coated electrode. Stick welding is also referred to as shielded metal arc welding (SMAW) or manual welding.
tapping A method of striking the arc in which the welder quickly moves the electrode downward to the base metal in a vertical direction. Tapping is one method used to start an arc in SMAW.
tensile strength A material's ability to resist forces that attempt to pull it apart or stretch it. Electrodes must create welds that at least meet the minimum tensile strength required to prevent the finished part from deforming or failing.
terminal A connecting point in a circuit where a wire is attached to create an electrical connection. Terminals can be either positive or negative.
T-joint A joint formed when the edge of one part is welded to the surface of another part in the shape of a T. T-joints are a very common joint type.
transformer power sources A welding machine that uses a transformer to supply electricity. Transformer power sources are comparatively inexpensive but large and inefficient.
transformers 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.
undercut An unintended void left in a finished weld. Different amounts of undercut are acceptable depending on the code being followed and the welding application.
vertical-position welding The welding position in which welding is done on a vertical surface, moving up or down. Vertical-position welding is more difficult than flat- or horizontal-position welding.
voltage A measure of electrical pressure or potential. Voltage is measured in volts (V).
volts V. A unit of measurement for electromagnetic force or pressure. The voltage between the electrode and workpiece in SMAW usually ranges from 14 to 45 volts.
weld backing A strip of metal located on the side opposite of the weld that provides a surface for depositing the first layer of metal and prevents molten metal from escaping through the joint. Weld backing can also be used to protect the back of the weld from atmospheric contamination.
weld bead The end product of a joint that has been welded. Weld beads are formed using a variety of different techniques.
weld penetration The depth to which the arc heat melts the joint below the surface of the base metals. The amount of amperage directly affects weld penetration.
weld pool The small area of molten metal that forms during welding. The cooled weld pool forms the permanent joint.
weld root The point at which the back of a weld intersects the surfaces of the base metals. Defects in welds can occur at the weld root.
welder A person who performs welding. Welders perform many arc welding processes, but SMAW is the most common.
welding helmets A protective eye and face covering worn during welding. Welding helmets protect the welder from the arc's harmful rays and intense bright light.
welding position The position in which the welder performs a weld. Welding positions include overhead-, vertical-, flat-, and horizontal-position welding.
wire brush A tool with wire filament used to remove burrs, scale, and flash. Using a wire brush to clean a metal is a method of joint preparation.
work cable The path used in welding to conduct electricity from the power source to the work clamp. Work cables and electrode cables connect the power source, workpiece, and electrode to create a closed electrical circuit.
work clamp A component that connects the work cable to the workpiece. The work clamp provides ground for the SMAW circuit.
workpiece The object or material being welded. Workpieces can be made out of a variety of materials when SMAW is used.