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Symbols And Conventions Used In Welding Documentation
The symbols and conventions used in welding documentation are specified in national and international standards such as ISO 2553 ''Welded, brazed and soldered joints -- Symbolic representation on drawings'' and ISO 4063 ''Welding and allied processes -- Nomenclature of processes and reference numbers''. The US standard symbols are outlined by the American National Standards Institute and the American Welding Society and are noted as "ANSI/AWS". Due in part to the growth of the oil industry, this symbol set was used during the 1990s in about 50% of the world's welding operations. An ISO committee sought to establish a global standard during this decade. In engineering drawings, each weld is conventionally identified by an arrow which points to the joint to be welded. The arrow is annotated with letters, numbers and symbols which indicate the exact specification of the weld. In complex applications, such as those involving alloys other than mild steel, more information may be cal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gas Metal Arc Welding
Gas metal arc welding (GMAW), sometimes referred to by its subtypes metal inert gas (MIG) and metal active gas (MAG) is a welding process in which an electric arc forms between a consumable MIG wire electrode and the workpiece metal(s), which heats the workpiece metal(s), causing them to fuse (melt and join). Along with the wire electrode, a shielding gas feeds through the welding gun, which shields the process from atmospheric contamination. The process can be semi-automatic or automatic. A constant voltage, direct current power source is most commonly used with GMAW, but constant current systems, as well as alternating current, can be used. There are four primary methods of metal transfer in GMAW, called globular, short-circuiting, spray, and pulsed-spray, each of which has distinct properties and corresponding advantages and limitations. Originally developed in the 1940s for welding aluminium and other non-ferrous materials, GMAW was soon applied to steels because it provid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Notation
In linguistics and semiotics, a notation is a system of graphics or symbols, characters and abbreviated expressions, used (for example) in artistic and scientific disciplines to represent technical facts and quantities by convention. Therefore, a notation is a collection of related symbols that are each given an arbitrary meaning, created to facilitate structured communication within a domain knowledge or field of study. Standard notations refer to general agreements in the way things are written or denoted. The term is generally used in technical and scientific areas of study like mathematics, physics, chemistry and biology, but can also be seen in areas like business, economics and music. Written communication Writing systems * Phonographic writing systems, by definition, use symbols to represent components of auditory language, i.e. speech, which in turn refers to things or ideas. The two main kinds of phonographic notational system are the alphabet and the syllabary. Some ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Upset Welding
Upset welding (UW)/resistance butt welding is a welding technique that produces coalescence simultaneously over the entire area of abutting surfaces or progressively along a joint, by the heat obtained from resistance to electric current through the area where those surfaces are in contact. Pressure is applied before heating is started and is maintained throughout the heating period. The equipment used for upset welding is very similar to that used for flash welding Flash welding is a type of resistance welding that does not use any filler metals. The pieces of metal to be welded are set apart at a predetermined distance based on material thickness, material composition, and desired properties of the finished .... It can be used only if the parts to be welded are equal in cross-sectional area. The abutting surfaces must be very carefully prepared to provide for proper heating. The difference from flash welding is that the parts are clamped in the welding machine and force is ap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shielded Metal Arc Welding
Shielded metal arc welding (SMAW), also known as manual metal arc welding (MMA or MMAW), flux shielded arc welding or informally as stick welding, is a manual arc welding process that uses a consumable electrode covered with a flux to lay the weld. An electric current, in the form of either alternating current or direct current from a welding power supply, is used to form an electric arc between the electrode and the metals to be joined. The workpiece and the electrode melts forming a pool of molten metal (weld pool) that cools to form a joint. As the weld is laid, the flux coating of the electrode disintegrates, giving off vapors that serve as a shielding gas and providing a layer of slag, both of which protect the weld area from atmospheric contamination. Because of the versatility of the process and the simplicity of its equipment and operation, shielded metal arc welding is one of the world's first and most popular welding processes. It dominates other welding processes in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Submerged Arc Welding
Submerged arc welding (SAW) is a common arc welding process. The first SAW patent was taken out in 1935. The process requires a continuously fed consumable solid or tubular (metal cored) electrode. The molten weld and the arc zone are protected from atmospheric contamination by being "submerged" under a blanket of granular fusible flux consisting of lime, silica, manganese oxide, calcium fluoride, and other compounds. When molten, the flux becomes conductive, and provides a current path between the electrode and the work. This thick layer of flux completely covers the molten metal thus preventing spatter and sparks as well as suppressing the intense ultraviolet radiation and fumes that are a part of the shielded metal arc welding (SMAW) process. SAW is normally operated in the automatic or mechanized mode, however, semi-automatic (hand-held) SAW guns with pressurized or gravity flux feed delivery are available. The process is normally limited to the flat or horizontal-fillet w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brazing
Brazing is a metal-joining process in which two or more metal items are joined together by melting and flowing a filler metal into the joint, with the filler metal having a lower melting point than the adjoining metal. Brazing differs from welding in that it does not involve melting the work pieces. Brazing differs from soldering through the use of a higher temperature and much more closely fitted parts than when soldering. During the brazing process, the filler metal flows into the gap between close-fitting parts by capillary action. The filler metal is brought slightly above its melting ( liquidus) temperature while protected by a suitable atmosphere, usually a flux. It then flows over the base metal (in a process known as wetting) and is then cooled to join the work pieces together. A major advantage of brazing is the ability to join the same or different metals with considerable strength. Basics High-quality brazed joints require that parts be closely fitted with base m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pressure Gas Welding
Principle of burn cutting Oxy-fuel welding (commonly called oxyacetylene welding, oxy welding, or gas welding in the United States) and oxy-fuel cutting are processes that use fuel gases (or liquid fuels such as gasoline or petrol, diesel, bio diesel, kerosene, etc) and oxygen to weld or cut metals. French engineers Edmond Fouché and Charles Picard became the first to develop oxygen-acetylene welding in 1903. Pure oxygen, instead of air, is used to increase the flame temperature to allow localized melting of the workpiece material (e.g. steel) in a room environment. A common propane/air flame burns at about , a propane/oxygen flame burns at about , an oxyhydrogen flame burns at and an acetylene/oxygen flame burns at about . During the early 20th century, before the development and availability of coated arc welding electrodes in the late 1920s that were capable of making sound welds in steel, oxy-acetylene welding was the only process capable of making welds of e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxyhydrogen Welding
Principle of burn cutting Oxy-fuel welding (commonly called oxyacetylene welding, oxy welding, or gas welding in the United States) and oxy-fuel cutting are processes that use fuel gases (or liquid fuels such as gasoline or petrol, diesel, bio diesel, kerosene, etc) and oxygen to weld or cut metals. French engineers Edmond Fouché and Charles Picard became the first to develop oxygen-acetylene welding in 1903. Pure oxygen, instead of air, is used to increase the flame temperature to allow localized melting of the workpiece material (e.g. steel) in a room environment. A common propane/air flame burns at about , a propane/oxygen flame burns at about , an oxyhydrogen flame burns at and an acetylene/oxygen flame burns at about . During the early 20th century, before the development and availability of coated arc welding electrodes in the late 1920s that were capable of making sound welds in steel, oxy-acetylene welding was the only process capable of making welds of e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxy-acetylene Welding
Principle of burn cutting Oxy-fuel welding (commonly called oxyacetylene welding, oxy welding, or gas welding in the United States) and oxy-fuel cutting are processes that use fuel gases (or liquid fuels such as gasoline or petrol, diesel, bio diesel, kerosene, etc) and oxygen to weld or cut metals. French engineers Edmond Fouché and Charles Picard became the first to develop oxygen-acetylene welding in 1903. Pure oxygen, instead of air, is used to increase the flame temperature to allow localized melting of the workpiece material (e.g. steel) in a room environment. A common propane/air flame burns at about , a propane/oxygen flame burns at about , an oxyhydrogen flame burns at and an acetylene/oxygen flame burns at about . During the early 20th century, before the development and availability of coated arc welding electrodes in the late 1920s that were capable of making sound welds in steel, oxy-acetylene welding was the only process capable of making welds of excepti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Induction Brazing
Induction brazing is a process in which two or more materials are joined together by a filler metal that has a lower melting point than the base materials using induction heating. In induction heating, usually ferrous materials are heated rapidly from the electromagnetic field that is created by the alternating current from an induction coil. Materials and applications "Induction brazing is suitable for many metallic materials, with magnetic materials being heated more readily. Where ceramic materials are involved, heating will most likely occur by conduction from surrounding metallic parts, or the use of a susceptor" (Sue Dunkerton, 1). According to Ambrell Group Application Labs talking about filler metals: Silver is frequently used for induction brazing because of its low melting point. Silver-copper eutectic brazes have melting temperatures between 1100°F and 1650°F. Aluminum braze, the least common, has a melting temperature of 1050°F to 1140°F. Copper braze, the least ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gas Tungsten-arc Welding
Gas tungsten arc welding (GTAW), also known as tungsten inert gas (TIG) welding, is an arc welding process that uses a non-consumable tungsten electrode to produce the weld. The weld area and electrode are protected from oxidation or other atmospheric contamination by an inert shielding gas ( argon or helium). A filler metal is normally used, though some welds, known as ''autogenous welds'', or ''fusion welds'' do not require it. When helium is used, this is known as heliarc welding. A constant-current welding power supply produces electrical energy, which is conducted across the arc through a column of highly ionized gas and metal vapors known as a plasma. GTAW is most commonly used to weld thin sections of stainless steel and non-ferrous metals such as aluminum, magnesium, and copper alloys. The process grants the operator greater control over the weld than competing processes such as shielded metal arc welding and gas metal arc welding, allowing for stronger, highe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
