Welding - Chapters 1-6 - First Exam, With Complete Verified Solution

Welding - Chapters 1-6 - First Exam, With Complete Verified Solution List welding Currents: AC,DC-,DC+ What is the Definition of welding current the current in the welding circuit during the making of the weld. Three units are used to measure welding current Voltage: electrical pressure Amperage: number of electrons flowing Wattage: power of the arc What approximately is The temperature of the arc? 11,000°F (6000°C). Three different types of current used for welding are Alternating Current: evenly distributed between (+) and (-) Direct-Current Electrode Positive: electrode positive, ground (work) negative Direct-Current Electrode Negative: electrode negative, ground (work) positive the voltage at the electrode before striking an arc (no current being drawn) Open-circuit voltage Operating voltage the voltage at the arc during welding Arc blow the deflection of the arc from its normal path because of magnetic forces. Duty Cycle percentage of time a welding machine can be used continuously at maximum amperage AC Alternating Current AWS stands for American Welding Society. 5 basic welding joints are lap, tee, edge, corner, butt 4 welding positions are flat, horizontal, vertical, and overhead 2 ways to strike an arc are tapping and scratching the distance the arc must jump from the end of the electrode to the plate or weld pool surface is? Arc length What Is The Measurement of the electrode to the surface of the metal? Electrode angle a straight weld with little or no side-to-side motion stringer bead A tack weld holds pieces together until final welding can take place. DC+ vs DC- DC+ will mean the current flows from the electrode to the base metal. This creates more heat at the electrode which creates less penetration but results in a better deposition. DC- gives you better penetration into the base metal but less filler metal is deposited. Conventional Flow Theory Starts at the positive and flows towards the negative. This is commonly illustrated in diagrams, but is not recognized as the chosen theory. Electron Flow Theory Theory which states electrons flow from negative to positive weld "a localized coalescence (the fusion or growing together of the grain structure of the materials being welded) of metals or nonmetals produced either by heating the materials to the required welding temperatures, with or without the application of pressure, or by the application of pressure alone, and with or without the use of filler materials.". smaw Shielded metal arc welding (SMAW) - also known as "stick welding", uses an electrode that has flux, the protectant for the puddle, around it. The electrode holder holds the electrode as it slowly melts away. Slag protects the weld puddle from atmospheric contamination. gtaw Gas tungsten arc welding... TIG..heliarc...manual welding process that uses a non-consumable tungsten electrode, an inert gas, and a separate filler material. gmaw Gas metal arc welding (GMAW) - commonly termed MIG (metal, inert gas), uses a wire feeding gun that feeds wire at an adjustable speed and flows an argon-based shielding gas or a mix of argon and carbon dioxide (CO2) over the weld puddle to protect it from atmospheric contamination. FCAW Flux-cored arc welding (FCAW) forge weld the most ancient welding processes, is a solid-state welding process that joins two pieces of metal by heating them to a high temperature and then hammering them together elihu thomson inventor of arc welding in 1886 OFW Oxyfuel Gas Welding, usually acytelene OFC Oxyfuel Gas Cutting Ideal process for high welding rates on thin-guage GMAW ppe Personal Protective Equipment GFCI Ground Fault Circuit Interrupter - Protect humans from deadly shock Type A fire extinguisher Combustible solids, paper, wood, and cloth. Green triangle symbol Type B fire extinguisher Combustible liquids, gas, oil, paint thinner. Red square symbol Type C fire extinguisher Electrical fires, motors, fuse boxes, welders, computers. Blue circle symbol Type D fire extinguisher Combustible metals, zinc, magnesium, and titanium. Yellow star symbol infrared light Infrared light has longer wavelengths, penetrates more deeply, has less energy, and produces more than visible light; makes up 60 percent of natural sunlight. Types of light that can cause burns ultraviolet and infrared ultraviolet (adj) of or relating to electromagnetic radiation having wavelengths shorter than those of visible light but lover than those of x-rays flash burn the damage that can be done to eyes after even brief exposure to ultraviolet light from arc welding. Flash burn requires medical attention. msds A widely used abbreviation for Material Safety Data Sheet. A MSDS contains details of the hazards associated with a chemical, and gives information on its safe use. Welding cables must never be spliced within ___ feet of the electrode holder 10 feet electrical resistance the property of some materials to block the flow of electrons. Measured in ohms electrical ground A conductive connection that provides a path for electrical current to pass from an electrical component into the earth. ansi American National Standards Institute: A private, non-profit organization that coordinates the development and use of voluntary consensus standards in the United States. ansi z89 ANSI rating required for hard hats to be used on the job. first degree burn Superficial burns through only the epidermis. second degree burn characterized by epidermal blisters, mottled appearance, and a red base? Damage extends into but not through the dermis. Recovery usually takes 2 to 3 weeks. third-degree burn a burn involving all layers of the skin; characterized by the destruction of the epidermis and dermis, with damage or destruction of subcutaneous tissue spot welding A form of resistance welding where the metal components being joined are clamped between two electrodes. An electric current is passed between the electrodes causing a build up of heat at the centre of the joint, fusing the two components together. Dangerous fumes from welding fumes from cadmium, lead oxide, and zinc are of particular concern to the welder amperage a unit of measure of the rate of flow of electricity through a wire inverter A device that converts DC to AC. duty cycle The percentage of time that the welding machine will weld at its highest rated amperes. magnetic flux lines imaginary lines that map out the magnetic field around a magnet SMAW - Definition Wellding process using a flux-covered metal electrode to carry an electrical current. The current forms an arc across a gap between the work and the electrode. Molten metal travels across the gap and joins together with the base metal. base metal Material being welded slag serves as a protective coating in the stick welding process; the more or less completely fused and vitrified matter separated during the reduction of a metal from its ore. Advantages of SMAW low cost, portable, and versatile Voltage - Welding is the measurement of electrical pressure in the same way that pounds per square inch is a measurement of water pressure. Voltage controls the maximum gap the electrons can jump to form the arc. A higher voltage can jump a larger gap. Welding voltage is associated with the welding temperature. Amperage - Welding (A), is the measurement of the total number of electrons flowing, in the same way that gallons is a measurement of the amount of water flowing. Amperage controls the size of the arc. Amperage is associated with the welding heat. Wattage - Welding (W), is a measurement of the amount of electrical energy or power in the arc. Watts are calculated by multiplying voltage (V) times amperes (A), Arc temperature range - SMAW 5500F - 36000F Averaging about 11,000F DCEN