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Joining Technologies
Published in Raghu Echempati, Primer on Automotive Lightweighting Technologies, 2021
Arc welding is a fusion welding process which uses a power supply to initiate and maintain an electric arc between an electrode and the base material to create a molten metal pool at the welding point. Arc welding can be accomplished either with direct current (DC) or alternating current (AC). The welding region is usually protected by some type of shielding gas, vapor, or slag.
Complying with Fire, Welding, and Hot Work Requirements
Published in Frank R. Spellman, Surviving an OSHA Audit, 2020
Welding is typically thought of as the electric arc and gas (fuel gas/oxygen) welding process. However, welding can involve many types of processes. Some of these other processes include inductive welding, thermite welding, flash welding, percussive welding, plasma welding, and others. McElroy (1980) points out that the most common type of electric arc welding also has many variants, including gas-shielded welding, metal arc welding, gas-metal arc welding, gas-tungsten arc welding, and flux cored arc welding.
Introduction
Published in P. Chakravarthy, M. Agilan, N. Neethu, Flux Bounded Tungsten Inert Gas Welding Process, 2019
P. Chakravarthy, M. Agilan, N. Neethu
In these processes, the faying surfaces of the parent metal and the filler metal (if required) melt and form an integral joint, which involves the fusion of the edges of the base metals to complete the weld. Fusion welds ordinarily do not require the application of pressure, and they may be completed with or without the requirement of filler metal. The requirement of filler metal generally becomes a necessity only when the thickness of the base metals to be joined is large enough, usually greater than 3 mm. Usually, fusion welding processes use a filler material to ensure that the joint is filled. The heat for fusion is supplied by various methods, and one of the common methods is through electrical energy. In arc welding, an alternating current (AC) or direct current (DC) power unit capable of supplying a high current but low voltage is used, and the arc is struck between an electrode and the base metal. Arc welding covers most of the welding processes under the fusion welding category. Though electron beam welding and laser beam welding are fusion welding processes, they are not categorized as arc welding processes because of the nature of the heat source.
Development of programmable system on chip-based weld monitoring system for quality analysis of arc welding process
Published in International Journal of Computer Integrated Manufacturing, 2020
Vikas Kumar, S. K Albert, N Chanderasekhar
Arc Welding is one of the most common and popular welding techniques because of its simplicity in operation, versatility and cost-effectiveness. Due to its inherent merits, this process is extensively used in almost all types of industries. Random arc behavior and various modes of metal transfer in an arc-welding process leads to dynamic variations in voltage and current while welding is in progress and hence, monitoring of this process is difficult. Welding process can be understood and analyzed in a much better way than it is done at present if we can record the variations that occur during the actual process itself at the same rate at which they occur. The challenge in developing such a mechanism is the random behaviour of the welding arc due to various physical processes that happen across the arc in a very short time while welding is in progress. These include metal transfer, short-circuiting, spatter, ionization, gas-metal reactions, etc. During welding, these variations are reflected as fluctuations in the current and voltage signals. If such dynamic variations that occur in voltage and current during welding can be properly acquired and analyzed, the same can be used to evaluate various welding parameters. The hardware employed for this purpose is commonly referred to as Weld Monitoring System (WMS) which consists of a data acquisition unit, display and processing unit and relevant sensors.
Workplace exposure to particulate matter, bio-accessible, and non-soluble metal compounds during hot work processes
Published in Journal of Occupational and Environmental Hygiene, 2019
Balázs Berlinger, Ulf Skogen, Conny Meijer, Yngvar Thomassen
“Hot work” is a term used for working with ignition sources near flammable materials, and to the extent that surface grinding of metals may cause sparks, it can also be classified as hot work. Thus, welding, flame and plasma cutting, air carbon arc gouging, and surface grinding are examples of hot work. During an arc welding process, an electric arc is created and maintained between a welding electrode and the base material to melt the metals at the point-of-contact.[1] In flame cutting, the part of the material to be cut is raised to ignition temperature by an oxygen-fuel (e.g., acetylene) gas flame.[2] During plasma cutting, an arc is formed between the electrode and the workpiece, which is constricted by a fine bore, copper nozzle. The plasma gas flow is increased so that the deeply penetrating plasma jet cuts through the material, and molten material is removed in the efflux plasma.[3] During air carbon arc gouging, an electric arc is generated between the tip of a copper-coated graphite electrode and the workpiece. The molten metal is blown away by high velocity air jet streams. This is an effective process to clean metal surfaces.[4] Surface grinding is used to plane the surface of a workpiece, remove surface coatings, mistakes, or excess material. A grinding wheel of aluminum oxide or silicon carbide is usually used in this process.[5]
Influence of welding fume metal composition on lung toxicity and tumor formation in experimental animal models
Published in Journal of Occupational and Environmental Hygiene, 2019
Patti C. Zeidler-Erdely, Lauryn M. Falcone, James M. Antonini
Approximately 1.2 million workers are regularly exposed to welding fumes in the U.S.[1,2] Given the variety of welding processes used in the workplace, welders are a diverse and heterogeneous group. The most common metal fusion process is electric arc welding. Specific types of arc welding include manual metal arc (MMA; also known as shielded manual metal arc [SMA]), gas metal arc (GMA), flux-cored arc (FCA), gas tungsten arc (GTA), submerged arc (SA), and plasma arc (PA). In arc welding, high temperatures of 5,000°C or more melt the joint between two metal work pieces as well as a filler material placed between them.[3] These extremely high temperatures are produced when an electric arc is established between the work pieces and a consumable wire electrode. As temperatures cool, the bond solidifies, firmly fusing the work pieces together. The bond created by welding is unique in that it is a mixture of the metal work pieces and the electrode filler material, making the bond extremely strong as it retains the strength of both initial metal parts.[1,3]